Climate Feedback

Why carbon dioxide concentrations over the past 24 million years or so have never dropped below 200 parts per million, despite environmental conditions that have been favourable for CO2 drawdown by rock weathering and sedimentation, has always been a bit of a mystery.

Now scientists suggest an almost provocatively simple mechanism that might have kept the planet from cooling more severely than it actually did during past glacial climates: Changes in terrestrial vegetation stopped the weathering-driven decline in atmospheric CO2 concentrations which else would have turned Earth into a lifeless freezer.

Weathering is known to be largely controlled by vegetation. So the team, led by Mark Pagani of Yale University, describes in a paper in Nature today a negative feedback whereby limited plant growth during cold conditions slows down the rate of weathering and sedimentation, thus preventing carbon dioxide levels from dropping even further. An editor's summary of the paper is here.

This “bold and provocative” hypothesis provides an “elegant twist” on existing ideas about climate-vegetation interactions, Yves Goddéris and Yannick Donnadieu write in an accompanying News and Views article (subscription required).

But the proposed feedback mechanism raises contentious issues as well. For example, Goddéris and Donnadieu argue that in the tropics the role of vegetation cover in the climate system might not be as significant as proposed.

Quirin Schiermeier

Posted by Quirin Schiermeier on July 02, 2009
Categories: Categories, Biosphere feedbacks, Climate Science, GHG emissions, Palaeoclimate, Quirin Schiermeier, Topics | Permalink | Comments (0) | TrackBacks (0)

Russia has been a rather puzzling actor in the complicated diplomatic game which resulted in the Kyoto protocol, and which will be played out again in Copenhagen in December. Climate warming doesn’t make headlines, and has so far not been a big concern, between Moscow and Vladivostok. What prompted Russian leaders to ratify Kyoto was the prospect of making good money from emissions trading, rather than conviction that man-made climate change is a real phenomenon and a threat to society.

Now they have changed their minds. In April, Vladimir Putin and his ministers approved a new climate ‘doctrine’ – well, that’s how they call these things in Moscow – which for the first time officially recognizes severe risks of global warming and calls for immediate action. My story over at Nature News explains the nature and significance of the baffling doctrine, details of which are beginning to leak.

Critics point out that Russia plans to focus on adaptation to climate change, while putting less emphasis on actually reducing its emissions. Others say Russia’s new climate policy has been quietly constructed behind closed doors, without any involvement from industry, NGOs and the public. That’s all true; but Russia’s recognition of the scientific basis of climate change, and its apparent willingness to pro-actively partake in international climate protection efforts, outweighs these flaws. Let’s see what Moscow will put on the table in Copenhagen.

Sure, all eyes in December will be on China, and Russia’s taciturn climate diplomacy has in the past been a fickle and half-hearted affair. Even so, one must not under-estimate Moscow’s influence at international negotiation tables.

The climatic importance of Russia’s natural landscape, in particular its boreal forests and its permafrost soils, is beyond doubt anyway. For example, huge amounts of old carbon that accumulated over thousands of years are stored in permafrost soils which occupy more than 60% of Russia’s 17 million square-kilometre land area. How much of it will be released as the southern permafrost boundary shifts northwards as a result of climate warming, possibly by up to 100 kilometres in the next 20-25 years?

A paper in Nature this week suggests that, globally, permafrost thawing may lead to the release of an extra billion tonnes of carbon per year into the atmosphere. The team measured carbon flows at a tundra site in Alaska where permafrost has been thawing for 20 years, and then calculated from the data the likely trajectory of global carbon release from thawing permafrost. Here's an editor's summary.

Russian scientists were not involved in the study, led by Edward Schuur of the University of Florida in Gainesville. That’s a pity. If Moscow’s new interest in climate led to more frequent east-west collaborations in science, such as on permafrost, it would be a boon.

Quirin Schiermeier

Posted by Quirin Schiermeier on May 28, 2009
Categories: Adaptation, Climate Policy, Climate Science, GHG emissions, Mitigation, Quirin Schiermeier, Topics, UN Conference on Climate Change, Copenhagen | Permalink | Comments (0) | TrackBacks (0)

This week’s Nature has an extended climate special made of original research papers, features, commentaries, editorials, essays and book reviews. Here’s the content at a glance.

An uplifting read the package is not, but this will hardly surprise devoted readers of these pages. What’s it all about then? Well, Gavin Schmidt and David Archer, in their news and views piece, get to the heart of it: “Dangerous climate change, even loosely defined, is going to be hard to avoid.”

Some highlights:
Malte Meinshausen and colleagues find that cumulative emissions from 2000 to 2050 of about 1,400 billion tonnes of CO2 yield a 50% probability of exceeding 2 °C warming – the somewhat randomly defined threshold of dangerous climate change - by the end of the twenty-first century Here's an editor's summary of the paper. Just to be clear: Known 2000-2006 emissions were almost 250 billion tonnes.

Myles Allen and colleagues take a slightly different approach to calculating the climate response to anthropogenic emissions. They show that cumulative emissions of one trillion tonnes of carbon (3,670 billion tonnes CO2) over the entire 1750-2050 period yield a 90% probability of warming between 1.3 and 3.9 °C above pre-industrial temperatures, with 2 °C of warming being the best estimate. About half a trillion tonne has been emitted since the onset of industrialization. Here's an editor's summary.

In clear, if we want a reasonably good chance of staying beyond 2°C warming, we cannot afford burning all the oil, gas and coal buried in the ground. We can’t actually afford burning more than half the proven reserves. If we continue burning fossil fuels at current rates we will leave the ‘safety zone’ in less than 20 years. Let’s face it: We have a bad hand – and we can’t bluff the planet.

Continue reading "The wheel of climate fortune" »

Posted by Quirin Schiermeier on April 30, 2009
Categories: Adaptation, Climate Science, Climate prediction, GHG emissions, Quirin Schiermeier, Topics, Uncertainty | Permalink | Comments (0) | TrackBacks (0)

Cross-posted from In the Field

It’s a warm and sunny spring day today in Vienna - can you guess then whether the coming summer will be colder or warmer than usual? Well, if you think that you hardly have more – though certainly not less - than a 50% chance of getting it right you’re, uhm, right. But guess what: Supercomputer-powered seasonal climate forecasts don’t do much better.

Seasonal climate predictions work relatively well only in the tropics. In Europe and North America their predictive skills are still pretty poor, meaning that forecast and observed climatology are often two very different things. And in some regions seasonal forecasts are actually worse than plain guessing.

This means that seasonal climate forecasts don’t yet provide reliable, if any, guidance for farmers, tourism managers, forest fire fighters, or for me and you. The idea that slowly varying boundary conditions, such as sea surface temperature distribution, snow cover and soil moisture, push the climate in a certain direction is well-established. But statistical climatology is one thing, daily wheather is another.

Andreas Weigel of the Swiss Weather Service, a rising star in the seasonal forecast community, made a few suggestions here at the EGU as to how predictive skills could be improved. Using more than one climate model is one promising possibility, statistical post-processing an re-calibrating forecasts is another, he explained in his well-received medal award lecture today

In the same session, Marie Boisserie of Florida Stae University in Tallahassee reported that when she included realistic initial soil moisture conditions to a climate model it greatly improved its predictive skills. Two-month forecasts of summer temperatures and precipitation in the US were more than twice as accurate than without the precipitation-derived soil moisture data.

Problem is that as yet there exists no reliable global observational database of soil moisture.
All eyes are now on the European Space Agency’s Soil Moisture and Ocean Salinity (SMOS) mission, designed to observe soil moisture over the Earth's landmasses and salinity over the oceans, to be launched in June.

Quirin Schiermeier

Posted by Quirin Schiermeier on April 21, 2009
Categories: Climate Science, Conferences and Meetings, Quirin Schiermeier, Topics | Permalink | Comments (0) | TrackBacks (0)

Last year, I reported on efforts to merge climate modelling with weather forecasting to create probabilistic climate predictions, with the ultimate aim of providing information that could aid adaptation.

Given enough money to build a world climate research facility with hundreds of petaflops of computing power, scientists could study simulations at the kilometre scale, and answer some of the big questions in climate science, such as how and when regions will be affected, concluded the World Modelling Summit for Climate Prediction last May.

Now, a group of scientists led by Suraje Dessai of the University of Exeter and the Tyndall Centre, UK argue that better climate predictions will not necessarily aid adaptation, and that waiting for better predictability in order to act on climate change would be a ‘significantly flawed’ approach.

Writing in the latest issue of EOS, a newsletter of the American Geophysical Union, Dessai and co-authors say that, in any case, the ability to predict future climate is limited by inherent uncertainty that will always leave ‘some level of irreducible ignorance in our understanding’. Furthermore, our ability to predict other factors that are likely to influence the outcome of adaptation efforts, such as population growth or changes in technology, is even more limited than our ability to predict the climate.

But this lack of predictability should not be seen as an excuse to postpone strategies for adaptation, they argue. After all, many organizations such as water authorities only need to know the range of possible representations of future climate to better understand their vulnerabilities. The authors call on decision makers to examine their adaptation strategies over a wide range of potential future scenarios of climate and other economic, political and cultural factors. Society will benefit more, they say, from knowing the vulnerability of climate-influenced decisions in the face of large uncertainty than from any foreseeable increase in the accuracy and precision of climate predictions.

Olive Heffernan

Posted by Olive Heffernan on April 08, 2009
Categories: Adaptation, Climate Science, Climate prediction, Olive Heffernan | Permalink | Comments (0) | TrackBacks (0)

Arctic sea ice continues to shrink, according to the latest satellite data. And in a scenario all too familiar to people of a certain age, the ice that is left has been replaced by a younger, thinner version of itself.

According to the US National Snow and Ice Data Center, the maximum extent of Arctic sea ice last winter was the fifth lowest on record. All sixth lowest maximums have occurred in the last six years (press release).

This year’s maximum was 15.16 million square kilometres, which is smaller than the 1979-2000 average by an area roughly the size of Texas (or France). Younger, thinner ice which melts every year is now 70% of Arctic sea ice, says the NSIDC, meaning melting is easier. In the 1980s and 90s this type of ice was between 40 and 50% of the total.

Read the rest of this post at Nature's The Great Beyond blog.

Posted by Olive Heffernan on April 07, 2009
Categories: Climate Science, Cryosphere, Daniel Cressey, Regional climate | Permalink | Comments (0) | TrackBacks (0)

Cross-posted from The Great Beyond

This week’s UN hosted climate change talks in Bonn, Germany, are well underway. According to New Scientist this climate summit is “more important than the G20”.

So what’s going on in Bonn?

This meeting is the first of five sessions leading up to what the UN says will be an “ambitious and effective international climate change deal” to be finalised in Copenhagen in December (pdf). The United Nations Framework Convention on Climate Change (UNFCCC) has already started its ‘countdown to Copenhagen’ timer.

However, as Reuters pointed out on Wednesday, delegates from 175 nations even managed to argue about what they were arguing about. The question is whether they should come up with a ‘treaty’, a ‘protocol’ an ‘agreement’, a ‘deal’, or a ‘decision’ to succeed the Kyoto protocol.

The first two would imply something legally binding, says the news wire, while the last would be non-binding. “It certainly has big legal implications,” Yvo de Boer, head of the UNFCCC, told Reuters on Tuesday.

Whatever the eventual wording is, developing nations think the more developed world should be trying harder. “We believe that by 2020 the [developed nations] should reduce their emissions by at least 40 percent below 1990 levels,” says Chinese delegate Xu Huaqing (Reuters).

Current US plans are much less ambitious than this, points out the BBC, being merely to limit emissions to 1990 levels by 2020.

“It is not the point in time in 2020 that matters - it is a long-term trajectory against which the science measures cumulative emissions,” says Jonathan Pershing, head of the US delegation. “The president has also announced his intent to pursue an 80% reduction by 2050.”

Continue reading "What’s going Bonn?" »

Posted by Olive Heffernan on April 03, 2009
Categories: Climate Science, Conferences and Meetings, Daniel Cressey, Features, GHG emissions, In the News, Mitigation, UN climate talks, Bonn, April 2009 | Permalink | Comments (0) | TrackBacks (0)

The clear message to emerge from the 3-day climate congress that wrapped up yesterday here in Copenhagen is that the prognosis on global warming is worse than anticipated by the IPCC in 2007. I reported the full story over on Nature News yesterday (no* subscription required). Here’s an excerpt:

The latest results made for bleak listening at times. Scientists cautioned that some of the impacts of global warming, such as sea level rise and loss of summer sea ice in the Arctic, are happening much sooner and more severely than scientists had estimated just two years ago. "What we are seeing now is that some aspects are worse than expected," says Stefan Rahmstorf, head of Earth System Analysis at the Potsdam Institute for Climate Impact Research in Germany and a plenary speaker at the congress.

What is also clear from my news story is the growing sense of frustration that the urgency of climate change is failing to permeate. While I imagine the climate community has felt that way for some time, it was palpable at a different level this week, I felt. For one, there seemed to be a lot of finger pointing – at the media for poor reporting, at policy makers and the public for failing to understand, and at scientists for failing to make the implications of their work more policy prescriptive.

I can’t help feeling that’s not going to bring us much closer to reducing greenhouse gas emissions. At the final plenary session of the congress, Danish PM Prime Minister Anders Fogh Rasmussen said that scientists who want a significantly more ambitious global carbon cut target of 80 percent by 2050 must not move the goal posts.

If this sense of frustration can be channelled into very clear communication on what needs to be done and when we need to start, could it increase the chances of an effective deal being reached in Copenhagen?

Olive Heffernan

*Correction: This article is now subscription only

Posted by Olive Heffernan on March 13, 2009
Categories: Climate Science, In the News, International Scientific Conference on Climate Change, March 2009, Olive Heffernan | Permalink | Comments (2) | TrackBacks (0)

I took part in a session today at the International Scientific Congress on Climate Change in Copenhagen on the role of the media in communicating climate change. Organised by Max Boykoff at the University of Oxford, the session brought together a diverse panel of journalists and academics who study media trends.

The backdrop to this session was quite interesting. Throughout the 3-day conference, there was a palpable sense of frustration among the scientific community that the media simply hasn’t done an adequate job in reporting climate change, and that it may be partly to blame for lack of public understanding and for inaction of the part of policymakers. This theme emerged in many of the talks on the first day alone.

There were many highlights from today’s session, but I’ll just mention a few. William Freudenberg of UC Santa Barbara said that climate scientists on the whole are being too optimistic about the prognosis for global warming and called for a new era of media coverage to highlight the conflict within the scientific community between what is ‘consensus’ and the reality of a more serious situation.

Naomi Oreskes of the University of California, San Diego, famous for her 2004 Science paper on the scientific consensus, said that the scientists needs to rethink their strategy on communicating climate change and asked whether they should collaborate with PR agencies to get their message across (she wasn’t advocating this, but asked whether this or other strategies could be employed to inform discussions on science more effectively).

James Kanter of the International Herald Tribune spoke of the role of the media as watchdog and pointed to a feature he investigated over five months last year on how electricity companies are making billions in windfall profits from the European ETS. RWE, a major German power company, and the biggest carbon dioxide emitter in Europe, received an estimated windfall of roughly €5 billion in the first three years of the system, more than any other company in Europe. The feature, which made the front page of the IHT in December, provoked a response from REW, which acknowledged the profits it had made (although said they wouldn’t be pocketed) and could serve as a warning to other cap-and-trade schemes under consideration.

My talk looked at the issue of whether a topic of socially and scientifically complex as climate change can be communicated effectively on blogs. The answer to this, in my view, is an unequivocal yes, for the following reasons. Back in August, Nature hosted the first international science blogging conference, where it was evident that bloggers are increasingly taking on the role of journalists in breaking news and providing genuine investigative reporting. That’s likely to become an emerging trend in the current economic climate, where traditional media outlets (think CNN) are seeing cutbacks in science reporting. Perhaps more importantly, as Gavin Schmidt of Real Climate previously pointed out, blogs can provide context to news and explain the significance of new research in a level of detail that can never by achieved by newspapers, which have a limited number of column inches dedicated to science.

Unlike many bloggers, journalists who blog have access to embargoed information, which means they can cover science stories as soon as they break, reaching a wide audience effectively and rapidly. But blogs can also provide a forum for scientists to engage more directly with society. While some argue that scientists (and indeed science journals such as Nature) should channel all discussion of research through formal routes such as ‘letters to the editor’, this will only ever reach a limited number of well-informed readers.

To communicate science to a wider audience, a faster and more accessible route is necessary.

Continue reading "Copenhagen: Why the media matters " »

Posted by Olive Heffernan on March 13, 2009
Categories: Climate Science, Conferences and Meetings, Features, In the News, International Scientific Conference on Climate Change, March 2009, Olive Heffernan | Permalink | Comments (1) | TrackBacks (0)

A sobering presentation by Marshall Burke of Stanford on future agriculture. He and colleagues looked at historical climate and yield data for various crops in various parts of the world and projected the relationship they found into various future climates as found in the IPCC. As the IPCC itself reported, much of the tropics did badly in this analysis, and the worst performer was maize in southern Africa which was down in yield by about 30% by 2030.

More granular data run out to 2050 showed similar or worse trends, and the rest of Africa did pretty badly too. So did other crops in the same countries, such as millet and sorghum, though as Andy Jarvis of Biodiversity International pointed out from the floor, this may be somewhat worst case. You don't just go on growing the same thing as the situation gets worse and worse. As climates change so will the crops farmers grow, which should help a bit.

While the IPCC has already predicted that tropical agriculture will have its productivity hit by any climate change, it said it expected that in temperate zones modest warming might help productivity. In at least one case Burke went into -- maize in the US -- there are studies suggesting things start going wrong much sooner than that, with yield losses of 30% or so by 2030. Modest rises have been seen: sharp downturns are to come. Burke says that an economic model fed with these and other gloomier-than-common yield assumptions suggests that prices are set to rise more steeply than the IPCC has foreseen: a 1ºC rise in temperature looks like a 25% increase in prices, hurting some poor farmers and a lot of poor consumers.

As Burke pointed out, we care about these food security issues because we care about people. A World Bank study suggests that the food crisis of 2007-2008 pushed 100m people into poverty. Reduced yields are normally bad for poor farmers, for whom consequent price increases rarely make up for lost production. They are also bad for the urban poor, who just see the price increases. That 25% increase in prices will some poor farmers and a lot of poor consumers. And on current trends that's just the beginning.

Posted by Oliver Morton on March 12, 2009
Categories: Climate Science, Conferences and Meetings, In the News, International Scientific Conference on Climate Change, March 2009, Oliver Morton | Permalink | Comments (1) | TrackBacks (0)

I had a look this morning at a breakdown of the press registration at this conference by country. Clear winners are Denmark and the UK, with 40 or so people each. Both of those are inflated figures, because some third-country and international organisations are covering the meeting out of Copenhagen and London (Japanese TV stations are listed as UK, for example, as is Al Jazeera English). But still there is a lot of genuine UK interest: national papers and the BBC. And the locals are out in force.

US representation, on the other hand, seems distinctly on the modest side. As far as I can see from the press room and by searching the papers' web sites there's no-one here from national papers (the Paris-based International Herald Tribune is a sort-of-exception) and not much broadcast. Time is listed as a media partner, but I haven't seen Bryan Walsh here. The rest of the world is represented at a pretty low level, but still here -- I was struck by a biggish contingent from Bangladesh.

Does it matter? Hard to say. The conference is hitting headlines, there are a lot of journalists for specialised outlets here, and the press room people say they are very happy with the level of coverage: Stefan Rahmstorf's sea-level talk on Tuesday, which I didn't see but which people here are talking about a lot, is getting a lot of pick up, to judge by Google News. But in the plenaries this morning John Schellnhuber and Nick Stern were reminding the thousand or so people in the room that this is one of the biggest stories in the world, and they were doing so pretty effectively. And part of the point of this meeting, as I understand it, is to take that same sort of approach and use it to set a scientific stage for the COP 15 "son of Kyoto" meeting, which will take place in the same large shed-like structure this December. By that standard, the coverage that I have seen (and I've been busy, to be fair, just talking to people at sessions, and may have missed lots of good stuff) seems a little thin.

Posted by Oliver Morton on March 12, 2009
Categories: Climate Science, Conferences and Meetings, In the News, International Scientific Conference on Climate Change, March 2009, Oliver Morton | Permalink | Comments (1) | TrackBacks (0)

It appears that the action on Wednesday afternoon was where I was not: in the session on tipping points. Chris Jones of the Met Office's Hadley Centre presented some studies of the Amazon (abstract in pdf) that have caused a big media stir. The studies suggest that a) there is a threshold level of warming beyond which much of the Amazon forest is committed to die back (probably being replaced by savanna) and b) that for significant parts of the forest that threshold is alarmingly low. Indeed it is quite possibly either unavoidable in the near future or already dwindling in the rear-view mirror. As I understand it from people who saw the presentation, models in which all the warming already in the pipeline (ie with no further emissions) is realised leave the forests pretty much committed to some dieback, and modest further warming seals the deal. I wasn't able to check that with Jones himself, but it seems to fit with what he and his colleagues write:

We present results to show a possible climate threshold beyond which some dieback is committed and this commitment rises dramatically for global temperature rise above 2 degrees C, a threshold often used by policy makers in their definition of dangerous climate change. Any subsequent recovery is on such a long timescale as to make the dieback effectively irreversible on any pragmatic level.

I'll see if I can find Chris Jones, or some Brazilians, or both to talk about this with on Thursday.

Posted by Oliver Morton on March 12, 2009
Categories: Climate Science, Conferences and Meetings, Features, In the News, International Scientific Conference on Climate Change, March 2009, Oliver Morton | Permalink | Comments (1) | TrackBacks (0)

Cross-posted from Heliophage

For those not eager to trawl through the aforementioned geoengineering tweetstream here's the most interesting thing I took from the geoengineering session -- a point on which, interestingly, David Keith and Ken Caldeira, who are keen to see and do more research on the topic, are close to agreeing with David Santillo of Greenpeace, who isn't.

The problem is in some ways pretty obvious: No one knows whether geoengineering can really be made to work. As Keith pointed out, even for the best characterised putative intervention -- a stratospheric aerosol like those produced by volcanoes -- the comparatively cursory research to date has turned up a wealth of complexities that have not yet been addressed by proponents, and more research will turn up even more of them. To Keith and Caldeira, this raises a nightmare scenario: that the world will have in the back of its mind that geoengineering is there as a fallback, will find that it needs a fallback, and will then find out that the fallback is not there in any practical sense. On this basis the sooner it is clear that there is no way out the better: time to do some serious research.

That is similar to Santillo's position, except he doesn't want to do the research needed to find out for sure. I took it from his talk that he wants instead to create a climate of opinion where the nagging hope that geoengineering might save us was firmly shut down more or less a priori, with commitment to emission cuts the sole and reaffirmed goal of all.

In making this argument, he came up with a nice pithy account of what he sees as the 5 drivers for geoengineering research: desperation, aspiration, fascination, delegation, remuneration. The first two he sees as essentially reasonable, the third -- "it is just such fun to play with these ideas!" -- troubling, the fourth -- "O good, someone else can solve the climate I don't have to" -- dangerous and morally defective (my term not his), and the fifth beyond the pale. (Actually in the presentation he didn't call the fifth driver "remuneration" he just called it "money" -- but he told me later he'd thought about listing it as remuneration, and I think it's slicker that way...)

What all these people agree on is that the lopsided way in which geoengineering is discussed, with a level of prominence in the media (and the unpublished musings of researchers, in my experience) and the imagination disproportionate to the actual level of knowledge among experts, needs to be seen as a real problem. Geoengineering is widely enough discussed that the thought it might be there as a last resort is widespread and quite possibly spreading wider, even though it still may be an illusion. Keith laid out the argument for reducing this disproportionality in a more formal way, looking at scenarios comparing the value of "Early Learning" v. late learning. I didn't note down all the details, but Early Learning seemed, by the economic metric he was using, to be a big, big winner.

PS: Those interested in the twittering per se may possibly want to check out this further post at Heliophage

Posted by Oliver Morton on March 11, 2009
Categories: Climate Science, Conferences and Meetings, Features, In the News, International Scientific Conference on Climate Change, March 2009, Oliver Morton | Permalink | Comments (0) | TrackBacks (0)

Over 2000 delegates from 80 nations have gathered this week in Copenhagen to update the global assessment of climate change, and I’m fortunate enough to be one of them.

Over the next few days, the International Scientific Conference on Climate Change will hear from world experts including climatologists, social scientists and economists on how the prognosis for global warming, and its physical and societal impacts, has changed since the Intergovernmental Panel on Climate Change (IPCC) issued its last report in 2007. The science in the 2007 report is now effectively 4-5 years out of date, so it’s clearly time for an update, which is why experts are here this week.

The updated assessment will be in the format of a 30-page synthesis document, to be published in June.
It will be peer-reviewed but not IPCC-style; that's because the ultimate aim of the congress is to deliver a hard-hitting message on the urgency of climate change to policymakers and the media ahead of the UN Conference in December, where delegates will again converge on Copenhagen, this time to agree a successor to the Kyoto Protocol.

Among the speakers who kicked off proceedings this morning was congress chair and marine scientist Katherine Richardson, who spoke to me ahead of time about why the congress is taking place and what it hopes to deliver. Read the full interview here.

I’ll be speaking in a session on Thursday on communicating climate change (and particularly on the role of blogs) and both I and my estimable colleague, Oliver Morton, will be blogging over the next few days on anything that especially surprises or interests us. For the full programme, see here.

Olive Heffernan

Posted by Olive Heffernan on March 10, 2009
Categories: Climate Science, Communicating Climate Change, Conferences and Meetings, International Scientific Conference on Climate Change, March 2009, Olive Heffernan | Permalink | Comments (2) | TrackBacks (0)

The Earth’s large forests take up substantially more atmospheric carbon dioxide through photosynthesis than they release back to the atmosphere through respiration. Thus acting as a carbon ‘sink’, they (and the oceans) are our closest natural allies in the fight against climate change.

But many forests are at threat - not only from logging and clearing, but from climate change itself.

Take drought. How will mature tropical rain forests respond to dryer conditions, which some climate models suggest might be ahead in the not-so-distant future?

The 2005 drought in the Amazon basin gave scientists an opportunity to find out. What they saw is not particularly heartening: Prolonged dryness has apparently turned some affected areas of the Amazon from a carbon sink to a carbon source, a team led by Oliver Phillips of Leeds University in Britain reports in Science today (Abstract here).

Patches subjected to a 100-milimetre decrease in rainfall released on average 5.3 tonnes of carbon per hectare – around 9 times the amount undisturbed tropical forests take up, on average, per year. Basin-wide, between 1.2-1.6 billion tonnes of carbon were released during the 2005 drought, the team estimates.

Over at Nature News, I’ve put together a little briefing on what we know and what we don’t know about the tropical carbon sink.

Quirin Schiermeier

Image: Punchstock

Posted by Quirin Schiermeier on March 06, 2009
Categories: Biodiversity and Ecology, Biosphere feedbacks, Climate Science, Deforestation, Mitigation, Quirin Schiermeier, Topics | Permalink | Comments (1) | TrackBacks (0)

Uncle Sam wants your observations of flowering and fruiting American plants. A new national ‘citizen science’ program is starting up in the US that asks volunteers to send in data on the seasonal cycles, or phenology, of local plants - information that researchers can use to track shifts caused by climate change and other factors. Animal-lovers can start contributing data next year. Running the effort is the USA-National Phenology Network, a consortium of universities, nonprofits, and government agencies - notably the US Geological Survey, who cover the new program on their latest podcast.

Says the press release:

Among other uses, data collected by USA-NPN will help resource managers predict wildfires and pollen production, detect and control invasive species, monitor droughts, and assess the vulnerability of various plant and animal species to climate change.

Continue reading "Wanted: Citizen climate scientists (shared Nobel Prize not guaranteed)" »

Posted by Anna Barnett on March 03, 2009
Categories: Biodiversity and Ecology, Climate Science | Permalink | Comments (2) | TrackBacks (0)

The loss of NASA's Orbiting Carbon Observatory (OCO), which last week ended up in the ocean rather than in orbit, is a hard blow not only to the team who devoted much of the last decade to getting it off the ground but to scientific – and especially climate - research.

There is quite literally of sense of grief among the climate research community, evident in the story by Jeff Tollefson and Geoff Brumfiel over on Nature News. My colleague Anna Barnett interviewed David Crisp, OCO Principal Investigator, ahead of the launch. His excitement about the mission was palpable as he spoke of how the NASA satellite would measure atmospheric carbon dioxide at a resolution 3 times higher than any previous space measurement of a trace gas.

The Japanese space agency successfully launched their Greenhouse Gases Observing Satellite (GOSAT) in January and undoubtedly this will provide some of the data that OCO would have collected. But OCO would have provided an unprecedented spatial resolution. Taking half a million carbon dioxide measurements per day, the satellite would have located specific sources of the greenhouse gas, differentiating cities and freeways from adjacent forested areas.

Not only is this a huge loss for exploratory science, the timing of the incident is especially unfortunate. With emissions rising and a global climate deal in the balance, pinpointing the origin and fate of carbon dioxide has never been more urgent — a task that the US$280-million mission would have accomplished skillfully.

So what’s next for NASA? Personally, I think the agency should make every effort towards a rapid re-launch, as I’ve detailed in my latest editorial. Getting an OCO replacement into orbit within the next few years would offer at least a brief period of data verification with GOSAT – one advantage of having two CO2 trackers in space simultaneously – and would have the added advantage of monitoring carbon heavyweights from space during the early stages of a post-2012 global climate deal.

Continue reading "NASA’s next challenge " »

Posted by Olive Heffernan on March 03, 2009
Categories: Climate Policy, Climate Science, Features, GHG emissions, In the News, Olive Heffernan, Technology | Permalink | Comments (2) | TrackBacks (0)

March 1 marks the official end of the 2-year-long International Polar Year so the news team at Nature is taking the opportunity to look back at the US $1.2 billion research program, which involved over 60 nations. A leader urges nations to build upon the achievements of the IPY and to carry out some of its unfinished business. In a feature story, Quirin Schiermeier assesses the overall polar year and looks forward toward some of the challenges ahead. A second feature by me surveys research in the Arctic that integrated indigenous peoples and their traditional knowledge. And a gallery feature by our art department spectacularly illustrates some of the projects at both poles, while evoking the sense of a remote research outpost. The photos and news in that gallery bring back memories of previous visits I’ve made to stations in Greenland and Antarctica.

The IPY leaders have produced their own 16-page report, available here, summarizing some of the key research findings, many of which Nature has already reported. Finally, don’t miss a special gallery of IPY-related photos that the World Meteorological Organization has on its site.

Rich Monastersky

Posted by Richard Monastersky on February 25, 2009
Categories: Climate Science | Permalink | Comments (0) | TrackBacks (0)

NASA’s long-awaited carbon dioxide detector, the Orbiting Carbon Observatory (OCO), crashed into the ocean near Antarctica today following a launch failure.

The $280 million mission would have provided much needed information on the origin and fate of carbon dioxide emissions. The instruments aboard the satellite were designed to measure carbon dioxide at a precision higher than any current space-based measurements of a trace gas, and would have helped scientists to identify sources and sinks of the greenhouse gas. Although the project was intended as a science mission, its results would also have been relevant to policymakers.

The loss of OCO marks a huge setback for the climate science community, and especially for the scientists who have worked so hard to get the satellite off the ground. Geoff Brumfiel reports over on Nature News (subscription):

It's a major setback," says Paul Palmer, a climate scientist at the University of Edinburgh, UK, who is part of the OCO science team. It will be particularly devastating for the tight-knit group of scientists and engineers who have devoted much of the past decade to the project. "These guys have sweated OCO for seven or eight years," he says.

The data from OCO would also have complemented those being collected by another satellite launched in January. The Greenhouse Gases Observing Satellite (GOSAT), a project of the Japanese Aerospace Exploration Agency, will now have to verify its measurements of methane, water vapour and carbon dioxide against those taken from ground-based stations.

Olive Heffernan

Posted by Olive Heffernan on February 24, 2009
Categories: Climate Science, Features, GHG emissions, In the News, Olive Heffernan, Technology | Permalink | Comments (2) | TrackBacks (0)

Cross-posted from In the Field

A leader of the the Intergovernmental Panel on Climate Change told the AAAS annual meeting in Chicago on Saturday that the world's climate is likely to change much faster than predicted, leaving the world with two choices: start cutting carbon emissions earlier, or make the cuts deeper.

The comments came the morning after former U.S. Vice President Al Gore called on scientists at the meeting to help convey a sense of urgency about climate change to policy makers and the public.

"We are basically looking now at a future climate that is beyond anything we've considered seriously in climate model simulations," said Chris Field, co-chair of the IPCC's second working group and a professor at Stanford University and the Carnegie Institution for Science.

This is because the rate at which carbon is entering the atmosphere is increasing much faster than the IPPC modeled in its last report, issued in 2007. That report estimated that world temperatures could increase by between 1.1 to 6.4 degrees Celsius by 2100. But the surge in the use of coal to generate power in developing countries, combined with climate impacts on natural carbon sinks, such as oceans, forests and tundra, mean that future climate impacts will likely be more severe than the IPPC realized, Field said.

"We have higher emissions, and we have a less friendly natural system to picking up these higher emissions, and they both mean that looking forward, the challenge of stabilizing atmospheric carbon dioxide is getting more complicated than we thought it was before," Field said.

Continue reading "AAAS: Climate issue getting "more complicated"" »

Posted by Anna Barnett on February 16, 2009
Categories: Climate Science, Climate prediction, Deforestation, Energy, Erika Check Hayden, GHG emissions | Permalink | Comments (2) | TrackBacks (0)

A couple of news items from the ocean fertilization front:

The Indo-German LOHAFEX experiment in the Southern Ocean, suspended two weeks ago, can be conducted as planned. Independent reviews sought by the German science ministry concluded that the experiment is in agreement with environmental standards and international law. On Tuesday, the team on board the German Polarstern started dumping its cargo of 20 tonnes of iron sulphate. The ship will stay around the area for around six weeks, giving the scientists’ enough time to observe the growth and decay of an ‘artificial’ algal bloom.

Picture: RV Polarstern (Alfred Wegener Institute)

It’ll be interesting how their observations, in particular concerning the rate and efficiency of carbon export to the deep ocean, will relate with data reported in a Nature paper this week on natural iron fertilization.

The CROZEX study was conducted in 2004 and 2005 near the Crozet archipelago at the northern boundary of the Southern Ocean. Raymond Pollard of the National Oceanography Centre Southampton and his team found that natural iron fertilization, by dust supplied from the Crozet Islands, increases biological production and the amount of organic carbon taken down into the deep ocean.

That’s not particularly surprising. But what’s amazing is this: The amount of carbon sequestered to 200 metres depth, while 18 times greater than that during an artificially induced bloom (like LOHAFEX), was a stunning 77 times smaller than the amount that had previously been determined during a natural bloom in the nearby Kerguelen region. What’s more, carbon flux at 3,000 metres, where carbon dioxide sucked up at the surface would be safely locked away for centuries, was just 3% of that at 100 metres. Check out this week's Nature podcast and the paper here (subscription)

“CROZEX carbon sequestration for a given iron supply (…) falls 15-20 times short of some geo-engineering estimates,” the authors conclude. This, you’ve guessed it, has “significant implications for proposals to mitigate the effects of climate change through purposeful addition of iron the ocean.”

It has indeed. The Nature news story here makes the point that the findings, if they hold up, could actually be the final blow to such proposals. The notion that putting a little iron into the oceans here and there will suck up most of the surplus atmospheric carbon dioxide is pretty much dead, so it seems. Alas, it was just too good to be true.

Quirin Schiermeier

Posted by Quirin Schiermeier on January 29, 2009
Categories: Climate Science, GHG emissions, Mitigation, Ocean science, Quirin Schiermeier, Topics | Permalink | Comments (2) | TrackBacks (0)

Ah, January in London. It’s gray. It’s clammy and damp. As I write, it’s begun to bucket rain unreservedly and, in my view, rather un-Britishly. Where’s the fog?

Heading here from the US last winter, I vaguely expected Dickensian mists to greet me. It was only after expatriation that I learned the old 'pea-soupers' were laden with noxious coal smoke, dispelled by environmental laws after a particularly deadly fog in 1952. Now a new paper in Nature Geoscience (subscription) quantifies similar trends across Europe - and the warming that has resulted.

Averaging visibility data from 342 weather stations across Europe, Robert Vautard at the Atomic Energy Commission in France and colleagues found what they call a “massive decline” - of roughly 50% - in foggy, misty and hazy days when visibility fell below 8 kilometres, 5 kilometres or 2 kilometres. [Update: That decline was over the last 30 years.]

The trend is particularly pronounced in eastern Europe. Tellingly, three available long time series show that visibility in Potsdam, in the former East Germany, didn’t start improving until sulphur dioxide emissions dropped off with the decline of the communist economy - noticeably later than the turnaround in the Netherlands and Switzerland. When Vautard et al. compare their visibility records to an inventory of SO2 emissions, they find that places with greater reductions in the pollutant from 1990-2000 also had greater increases in visibility.

Fog forms around airborne particles, including pollutants, Dave Britton of the UK Met Office explains to the Guardian: "Go back to the 1950s and the big pea-soupers in London came from the amount of crap that people were putting out of their chimneys from coal fires." Since then measures like London's Clean Air Acts have played a role in clearing things up.

But they also may have inadvertently warmed the continent, the authors say. A standing problem in climate science is to account for the 0.5 C average temperature rise in Europe in the last three decades, which models don’t reproduce. Correlations between visibility and temperature suggest that lifting the fog could have contributed 10-20% of daytime temperature rises in Europe overall, and about half in central and eastern Europe.

Continue reading "Fog clears, Europe warms [updated]" »

Posted by Anna Barnett on January 19, 2009
Categories: Anna Barnett, Climate Science, In the News | Permalink | Comments (0) | TrackBacks (0)

In the latest issue of Nature Reports Climate Change, we have a round-up by Amanda Leigh Mascarelli of some of the major breakthroughs in climate science in 2008. This is a just a pick of the top five; there are of course others we could have mentioned. Also listed are those issues where large gaps remain in our knowledge, such as how fast Greenland is melting, or on which agreement has yet to be reached, such as where to stabilize atmospheric greenhouse gas concentrations.

All illustrated with a cartoon by Marc Roberts:

Please share others with us in the comments.

Posted by Olive Heffernan on December 23, 2008
Categories: Climate Science, Olive Heffernan | Permalink | Comments (1) | TrackBacks (0)

As speculation grows that agreeing a global deal on climate change may extend well beyond the 2009 deadline, the risk of overshooting the EU’s target to limit the increase in global temperature to 2°C over pre-industrial levels looks increasingly likely.

The target is based on scientific evidence that below a 2°C increase, some of the worst impacts of climate change would be avoided. In its fourth assessment report, the IPCC calculated that limiting warming to that extent would mean stabilizing atmospheric concentrations at roughly 450 ppm CO2-equivalents.

But it’s clear at this year’s AGU that much uncertainty, and disagreement, remains on whether 2°C is an appropriate target and on the atmospheric greenhouse gas concentrations that equate to a given amount of warming.

Speaking here yesterday, James Hansen, director of the NASA Goddard Institute of Space Studies, called for atmospheric greenhouse gas concentrations to be restricted to 350ppm. Hansen also recently advised the UK government’s Environmental Audit Committee that the 2°C target should be revised to a 1°C increase above pre-industrial levels. Meanwhile, many of the scientists presenting work here are wrangling with whether stabilizing at 450ppm – or higher – is economically and technologically feasible.

The debate on where to stabilize is largely due to what Stanford’s Stephen Schneider dubs ‘double-barrelled uncertainty’ a term that encompasses the unknown factor in how far we can reduce emissions and in how the climate system will respond to any reductions we make.

The latter uncertainty – that inherent in the system – is measured in terms of climate sensitivity i.e. how much warming would occur if atmospheric GHG concentrations were doubled. This is currently estimated at 2-4.5°C, but Schneider said here on Tuesday that it’s more important for society to know the uncertainty around this range i.e. the chance that we will see a much larger degree of warming than anticipated for various atmospheric concentrations.

Given the fact that a massive reduction in emissions in the coming decades it is very unlikely, he says, and the fact that we could overshoot our target anyway, we need to take a serious look at the consequences. Schneider suggests that the IPCC should take it on board to evaluate climate scenarios for overshooting to 600 ppm and then subsequently reducing atmospheric concentrations to say 500ppm or 450ppm.

Continue reading "AGU 2008: Uncertainty and overshooting 2°C" »

Posted by Olive Heffernan on December 18, 2008
Categories: AGU, Climate Science, Climate prediction, GHG emissions, Olive Heffernan | Permalink | Comments (4) | TrackBacks (0)

In what could be good news for the Earth’s ability to mitigate warming, scientists have reported that deep convection has resumed in the North Atlantic after more than a decade of little activity.

Also known as overturning, deep convection transports cold water to depths of more than 1000m, bringing carbon dioxide with it and keeping the greenhouse gas out the atmosphere for centuries. It's also partly reponsible for maintaining the global climate system, as we know it - at high latitudes, deep convection forms a mass of cold water that drives the Atlantic oceanic conveyor belt and carries warm water northwards.

In the past decade, however, the process of deep convection has been sluggish, causing some to speculate that warming of surface waters due to climate change is already taking its toll on ocean circulation.

Its recent return has now been independently reported by two groups of scientists; the first team, led by Kjetil Våge of the Woods Hole Oceanographic Institution in Massachusetts, publish their data in the latest issue of Nature Geoscience. Igor Yashayaev and John Loder of the Bedford Institute of Oceanography in Nova Scotia, Canada, have a forthcoming paper in Geophysical Research Letters.

Continue reading "There’s life in the cold sink yet " »

Posted by Olive Heffernan on December 02, 2008
Categories: Climate Science, Features, In the News, Ocean science, Olive Heffernan | Permalink | Comments (0) | TrackBacks (0)

A paper this week in Nature (subscription) sheds new light on the causes of pronounced greenhouse-gas and climate fluctuations during glacial times.

The last ice-age, which covered the period from around 110,000 to 10,000 years before now, is famed for a series of climate swings known as Dansgaard-Oeschger events.

Scientists have found evidence in Greenland ice cores for abrupt warming episodes of up to 15 degrees Celsius within few decades, followed by a more gradual cooling. These glacial warm and cold periods swung back and forth between the poles in a kind of thermal seesaw effect, whereby Antarctic temperatures rose when Greenland temperatures dropped, and vice versa.

It has long been assumed that Dansgaard-Oeschger events were triggered by changes in Atlantic ocean-circulation. The new modelling study by Andreas Schmittner and Eric Galbraith now adds new evidence to the idea. Weakening Atlantic meridional overturning circulation, the heat conveyor which carries warm water surface water northwards and cold deep-water back south, is indeed the primary physical mechanism driving glacial climate fluctuations, they conclude. Here’s an editor’s summary.

Schmittner and Galbraith carried out simulations with a coupled model of glacial climate and (simplified) biogeochemical cycles. When they manipulated the Atlantic circulation – artificially ‘switching’ it off and on in their model, that is - the model nicely reproduced the temperature changes typical for Dansgaard-Oeschger events. Remarkably, the model also reproduced reasonably well the ice-core-derived changes in atmospheric concentrations of the greenhouse-gases carbon dioxide and nitrous oxide which accompany such events.

Continue reading "Glacial climate swings: It’s in the ocean" »

Posted by Quirin Schiermeier on November 20, 2008
Categories: Climate Science, Ocean science, Palaeoclimate, Quirin Schiermeier, Topics | Permalink | Comments (0) | TrackBacks (0)

Scientists have reported the first direct evidence of a link between flooding underneath the Antarctic ice sheet and the rate at which glaciers are discharged into the sea. The study, which was published online on Nature Geoscience yesterday [subscription], has important implications for understanding how ice released into the ocean from the Greenland and Antarctic land masses could raise sea level.

Led by Leigh Stearns of the Climate Change Institute at the University of Maine, the trio of researchers found that ice on the Byrd Glacier in East Antarctica accelerated just as there was a massive release of water from lakes beneath the ice.

Over the past 20 years, researchers have discovered more than 150 lakes beneath the Antarctic ice pack, the largest of which (Lake Vostok) is equal in size to Lake Ontario in Canada.

And more than a year ago, researchers reported that these subglacial lakes could actually lubricate the flow of ice off the continent and into the ocean, as I reported over on Nature News at the time.

Continue reading "Under-ice floods speed glaciers towards the sea " »

Posted by Olive Heffernan on November 17, 2008
Categories: Climate Science, Cryosphere, Features, Journal Club, Olive Heffernan | Permalink | Comments (0) | TrackBacks (0)

With a month to go until its official finish, the 2008 Atlantic hurricane season has seen more damage, as measured in dollars, than any other year except the monster 2005 season. Scientists have yet to agree whether human-induced climate change has caused spiking Atlantic hurricane activity since the early 1990s - and while the season has raged on, researchers have continued to go back and forth on whether worse is in store as the ocean keeps warming. Science this week has the latest salvo in the longtime debate: a Perspective (subscription) by Gabriel Vecchi of NOAA, Kyle Swanson of the University of Wisconsin-Milwaukee, and Brian Soden of the University of Miami.

Warming sea surface temperatures (SSTs) in the Atlantic, thought to fuel hurricanes, are correlated with the recent surge in storm activity. The trend is roughly linear, note Vecchi et al., and extending it along with predicted temperature rises implies that by 2100, a hurricane season like 2005’s might be considered mild.

But that’s only true, they caution, when you look at absolute temperatures. Relative warming - the Atlantic heating up even more than other tropical seas - is equally well-correlated. Citing their recent papers in Nature and Geochemistry, Geophysics and Geosystems, and Knutson et al. in Nature Geoscience, the authors make an argument that relative warming is more likely to be the true cause of increasing activity. And relative warming of the Atlantic sea surface, in contrast to absolute warming, doesn’t keep trending upwards in 21st-century climate predictions.

Continue reading "Hurricanes and sea surface temperature: all relative?" »

Posted by Anna Barnett on November 03, 2008
Categories: Anna Barnett, Atmospheric Science, Climate Science, Hurricanes | Permalink | Comments (0) | TrackBacks (0)

Humans are at fault for warming at both the Earth’s poles: so say unique findings published in Nature Geoscience today.

With stories of dwindling sea ice and collapsing ice shelves already saturating the media, this at first may hardly sound like news. But in fact, researchers had never formally pinned the Arctic’s rapid warming on humans, because limited data were swamped by great natural variability. Down south, where warming on the Antarctic Peninsula contrasts with cooling in some other regions of the continent, the IPCC’s 2007 assessment report concluded: “Anthropogenic influence has been detected in every continent except Antarctica (which has insufficient observational coverage to make an assessment)”.

In the new study, Nathan Gillett of the University of East Anglia and colleagues found a way to squeeze clear results from those sparse data. Their method was based on state-of-the-art models of the polar climates that either incorporated anthropogenic as well as natural influences on variability, or included natural factors only. (Human influences include greenhouse gases that cause warming and a cooling effect from depletion of stratospheric ozone; natural ones are solar variation and volcanic eruptions.) This type of study, pioneered by Peter Stott and co-authors in 2000, has greatly boosted the IPCC’s confidence that humans are causing climate change globally. The new Gillett et al. study - co-authored by Stott - gave the technique an important tweak, say Andrew Monaghan and David Bromwich in an accompanying News and Views article, by focusing on model results for only those places with observational temperature records:

By this restriction, the group is able to perform an ‘apples with apples’ comparison of model simulations and polar near-surface temperature records during the twentieth century. Their analysis implies that the models can simulate trends better than previous studies had suggested.

In the records since 1900 put together by Gillett et al., the average temperature across monitoring stations has risen at both poles. And the models match these trends only when they factor in all influences, including human hands (producing the line labelled ALL in the above figure).

“We detected the human fingerprint in both the Arctic and Antarctic regions,” says Gillett. The familiar litany of impacts - balding Arctic summer sea ice, ecological and human displacements, sea level rise - are likely down to us too, the authors say. Stott adds that the results make the poles’ future all the bleaker, since “the human component isn’t going to let up anytime soon.”

Continue reading "Human prints on the poles" »

Posted by Anna Barnett on October 30, 2008
Categories: Anna Barnett, Attribution, Climate Science, Cryosphere | Permalink | Comments (6) | TrackBacks (0)

I'm here in Kailua Kona for the AGU Chapman conference on atmospheric water vapor and its role in climate. Given the high humidity and afternoon rain, the topic seems quite appropriate.

In the keynote lecture, Brian Soden of the University of Miami gave a great introduction to the role of water vapor in climate change. It seems to be a general consensus that there is a positive feedback between water vapor and climate. There has been an increase in water vapor in the atmosphere over the past 15 years, and Soden reported that model simulations show that greenhouse gas emissions are at least in part to blame.

He suggests that increasing atmospheric water vapor will play havoc with atmospheric circulation. Wet regions will get wetter while arid regions will dry even more. In addition, floods and droughts will become more frequent and more extreme.

Continue reading "AGU Chapman conference: water vapor and climate" »

Posted by Anna Barnett on October 22, 2008
Categories: AGU Chapman Conference on Atmospheric Water, Alicia Newton, Atmospheric Science, Climate Science | Permalink | Comments (0) | TrackBacks (0)

Cross-posted from Daniel Cressey on The Great Beyond

Cyclones appear to be responsible for a large amount of organic carbon tied up in ocean sediments.

In a paper published in Nature Geoscience, Robert Hilton and colleagues report on the impact of cyclone-induced floods on carbon in the LiWu River in Taiwan. They found that between 77 and 92% of non-fossil carbon eroded from the LiWu catchment area was moved during floods linked to cyclones.

As increased sea surface temperatures from global warming could increase the intensity of cyclones, this could create negative feedback, with bigger cyclones locking up more organic carbon in sediments. Sadly this is not going to stop global warming.

Continue reading "Cyclones’ carbon capturing" »

Posted by Anna Barnett on October 20, 2008
Categories: Atmospheric Science, Climate Science, Daniel Cressey, Earth science, Hurricanes, Ocean science | Permalink | Comments (0) | TrackBacks (0)

It's a buried time bomb of greenhouse emissions - and it's even less photogenic than melting permafrost. A team of researchers led by Takeshi Ise of the Japan Agency for Marine-Earth Science and Technology has been watching peat dry.

Peat - "an accumulation of partially decayed vegetation matter", in Wikipedia's appetizing phrase - forms in bogs and swamps where the acidic, waterlogged, oxygen-poor soil smothers the decomposition process, just as permafrost freezes it out. That makes it a big sink for carbon that would otherwise have joined the atmosphere as the plants composted. But peat's not just a sink, it's a sump - and a snowballing one. The large amount of water peat can hold lowers the oxygen available, which makes more peat accumulate, which sucks up more groundwater and blocks it from draining.

It's this feedback process, as it occurs in the northern bogs of Manitoba, Canada, that Ise et al. succeeded in accurately modeling for the first time in a paper published this week in Nature Geoscience (subscription required). Their bad news is that warming air temperatures reverse the loop: the peat dries and decays, then can't hold as much water and dries and decays some more.

As Joseph Romm points out on Grist and Climate Progress, that potentially makes the peat loop a link in a bigger, and climatically more important, vicious circle - the one where temperatures raised by human emissions start an uncontrollable release of methane and carbon dioxide from natural stores like peat and permafrost.

Continue reading "Watching peat dry" »

Posted by Anna Barnett on October 16, 2008
Categories: Anna Barnett, Biosphere feedbacks, Climate Science, Earth science | Permalink | Comments (0) | TrackBacks (0)

For the long view on the 2008 Arctic sea ice melt, see today’s commentary on Nature Reports Climate Change by two National Snow and Ice Data Center researchers. Mark Serreze and Julienne Stroeve recap the results:

The seasonal minimum for 2008, occurring on 14 September, entered the books as the second-lowest of the satellite era, probably the second-lowest of at least a century, and just behind the standing record set in 2007.

Barely second-lowest still came as a shock, given the cooler weather this year. Said Stroeve in an NISDC press release, “I find it incredible that we came so close to beating the 2007 record — without the especially warm and clear conditions we saw last summer. I hate to think what 2008 might have looked like if weather patterns had set up in a more extreme way. ”

August 2008 saw the fastest melt ever recorded, according to NASA. And ice volume, a bellwether for the future, probably was at its lowest this year - an observation that hasn’t reached the broadsheets (but see Climate Progress and Stoat).

NSIDC scientist Walt Meier explains, “Warm ocean waters helped contribute to ice losses this year, pushing the already thin ice pack over the edge. In fact, preliminary data indicates that 2008 probably represents the lowest volume of Arctic sea ice on record, partly because less multiyear ice is surviving now, and the remaining ice is so thin.”

Continue reading "Has Arctic summer sea ice tipped?" »

Posted by Anna Barnett on October 09, 2008
Categories: Anna Barnett, Climate Science, Cryosphere | Permalink | Comments (4) | TrackBacks (0)

“In the 1970s, all the scientists were saying an ice age was coming.” This seems to be a popular sentiment echoed in blogs and novels aimed at challenging the consensus views regarding future climate change. It was even a key theme in Michael Crichton’s State of Fear , when a character suggests that scientists only jumped on the global warming bandwagon in a bid to secure funding.

But a new article in the Bulletin of the American Meteorological Society challenges the idea of a 'global cooling ' consensus. Thomas Peterson of NOAA teamed with William Connolley of the British Antarctic survey and science reporter John Fleck to create a survey of peer-reviewed climate literature from the 1970s. Looking at every paper that dealt with climate change projections or an aspect of climate forcing from 1965 to 1979, they were able to assess the ‘trends’ in the literature. They found that only 7 of the 71 total papers surveyed predicted global cooling. The vast majority (44) actually predicted that rising atmospheric carbon dioxide could lead to global warming.

Continue reading "The great global cooling myth" »

Posted by Alicia Newton on October 07, 2008
Categories: Alicia Newton, Climate Science, Climate prediction, Communicating Climate Change, GHG emissions | Permalink | Comments (12) | TrackBacks (0)

The Great Plains of the United States, late twenty-first century: breadbasket or dust bowl?

It may depend on groundwater storage, finds a study published in Nature Geoscience this week (subscription required). The results are based on an unusually sophisticated watershed model that connects the below-ground water sources, surface water and the land surface itself.

Continue reading "Breadbasket or dust bowl?" »

Posted by Anna Barnett on September 30, 2008
Categories: Anna Barnett, Climate Science, Earth science, Regional climate | Permalink | Comments (3) | TrackBacks (0)

I wrote here yesterday that ‘I don’t think that anyone knows for sure how close we are to reaching tipping points in the climate system’. As it so happens, a pair of articles published in Proceedings of the National Academy of Sciences this week illustrates this point nicely.

The first is a Perspective by atmospheric scientist V Ramanathan and postdoctoral researcher Yan Feng from the Scripps Institution of Oceanography at the University of California, San Diego, who argue that the Earth is now committed to a 2.4°C rise in temperature above pre-industrial levels.

Anything above a 2°C increase is generally considered to be ‘dangerous’ climate change and would likely trigger several of the Earth’s tipping points, such as the complete loss of Arctic summer sea ice and melting of the Greenland ice sheet. And according to the IPCC, a rise in global temperature by 1-3°C will commit the planet to widespread loss of biodiversity, widespread deglaciation of the Greenland Ice Sheet, and a major reduction of area and volume of Hindu-Kush-Himalaya-Tibetan glaciers, which provide the head-waters for most major river systems of Asia.

The authors argue that for atmospheric greenhouse gas concentrations to remain constant at 2005 levels for the rest of the century, aggressive emissions reductions would be required – yet emissions are rising.

Currently, the warming effect of greenhouse gases in the atmosphere is being masked by the cooling effect of other air pollutants – such as smoke from cooking and agricultural waste burning – that create a dimming effect at the Earth’s surface.

Assuming policies to reduce these air pollutants are successful, the full warming potential of greenhouse gases will soon be realized. So as air pollution measures become effective (and much headway is being made here), the need for reducing carbon dioxide emissions becomes even more urgent, say Ramanathan and Feng.

Continue reading "Could tipping happen any time soon? " »

Posted by Olive Heffernan on September 26, 2008
Categories: Climate Policy, Climate Science, Features, GHG emissions, Journal Club, Mitigation, Olive Heffernan | Permalink | Comments (3) | TrackBacks (0)

Cross posted from The Great Beyond

The latest global carbon budget numbers are just out, and they make interesting, if slightly depressing, reading. (Global Carbon Project site – will be updated at midnight)

Most striking is that, despite years of effort, carbon dioxide emissions are increasing at an alarming rate of 3.5% a year– faster than the 2.7% predicted by the IPCC in their worst case scenario, and miles ahead of the 0.9% annual rise in the 1990s. Worst still, current measures have been based on a middle-ground IPCC scenario. Pep Candell from the Global Carbon Budget told me that this was “astonishing”.

For the first time, we have hit 10 billion tonnes of carbon emitted annually.

The other thing to note is that China and India are galumphing their way up the table of biggest carbon dioxide emitters. Ten years ago the top four were: USA, China, Russia, Japan. Today that list reads: China, USA, Russia, India – and I am assured by Candell that next year India will have jumped into third place.

This is a worry – when the Kyoto Protocol was first talked about, the countries of the developing developed world were overwhelmingly the highest emitters of CO2. But in the meantime, whilst decisions were made, details argued out and paperwork signed, the developing world has taken pole position.

China has, since 2002, jumped from being responsible for 14% of the global carbon dioxide emissions, to 21%. At the same time the US has been hovering at around 20%.

Slightly good news is that our natural saviours - the oceans, forests and soil, are still doing a sterling job. In 1959, natural sinks removed just over 50% of the carbon dioxide man emitted. And today, they do the same - gobble up just over half. The efficiency of these natural sinks has dropped by about 5% in the intervening years, which isn't ideal, but means that the overall news is not disastrous.

Response to the news – which will be officially announced tomorrow – from the media is widespread. It’s a ‘reality check’ according to the Daily Green; Zee News runs with the rise of India in the emission charts; while other reports tell it like it is: carbon dioxide emissions still rising.

Katharine Sanderson

Posted by Olive Heffernan on September 25, 2008
Categories: Climate Science, Features, GHG emissions, In the News | Permalink | Comments (4) | TrackBacks (0)

Cross posted from The Great Beyond

The contentious ‘hockey stick’ climate change graph has again been upheld as broadly accurate, doubtless to the rage of climate denialists/sceptics/whatevers.

A team led by Michael Mann of Penn State University has looked at a whole range of proxies for surface temperatures over the last 2,000 years in an attempt to counter criticism of the graph, which showed a long ‘handle’ and a sharp upturn (the blade).

Their findings? As the Christian Science Monitor puts it: “It still looks a lot like the much-battered, but still rink-ready stick of 1998. Today the handle reaches further back and it’s a bit more gnarly. But the blade at the business end tells the same story.”

The previous hockey stick had been accused of relying too much on data from tree rings so this PNAS study may silence some of the critics when it appears later.

Continue reading "Jolly hockey sticks " »

Posted by Olive Heffernan on September 02, 2008
Categories: Climate Science, Climate variability, Daniel Cressey, Features, In the News, Palaeoclimate | Permalink | Comments (4) | TrackBacks (0)

Arctic permafrost has been the subject of much global warming worry, but not so much detailed research. A new survey of North American Arctic permafrost published in Nature Geoscience this week (subscription required) breaks new ground, literally.

News accounts have focused on the paper’s bottom-line estimate: there is 60% more carbon frozen up there than previously thought. That’s a total of 98.2 billion tonnes of carbon, one-sixth of the amount currently circulating through the atmosphere.

Existing estimates already show more permafrost carbon around the globe than atmospheric carbon. If warming - which is happening faster in the Arctic than anywhere else - releases even a small portion of that store into the atmosphere as carbon dioxide and methane, the results won’t be pretty, especially if the amount frozen in the Asian north is also more than expected. Permafrost has been called a “slow-motion time bomb”, and the effects of its melting are not included in most global climate models.

The new research is by Chien-Lu Ping of the University of Alaska Fairbanks and colleagues. How did they do it?

Continue reading "Permafrost study breaks ground" »

Posted by Anna Barnett on August 29, 2008
Categories: Anna Barnett, Climate Science, Cryosphere, In the News | Permalink | Comments (3) | TrackBacks (0)

I’m all for a website that distills climate science papers into something easily understood by the general public, especially if it avoids the hype and hysteria all too often employed by headline news.

Such is the claim of CO2 Science, a weekly newsletter published by the not for profit Center for the Study of Carbon Dioxide and Global Change, with issues that include editorials, book and media reviews, and mini-reviews of the recent peer-reviewed literature.

But rather than its promise of “separating reality from rhetoric in the emotionally-charged debate that swirls around the subject of carbon dioxide and global change”, on the contrary CO2 Science twists the most recent science, ever so subtly, to suggest that there is no link between carbon dioxide levels and climate change.

For a case in point, check out the feature entitled “Medieval Warm Period Record of the Week”. This showcases records of temperature or environmental changes during the Medieval Warm Period (aka the Medieval Climate Anomaly). The conclusion is that if the MWP was warmer than present – still debated – obviously CO2 isn’t driving current warming. There is even a list of 576 scientists who have found evidence for the MWP – the thinly veiled conclusion being that they agree that an increase in CO2 isn’t behind the recent climate change.

FYI scientists – if you’ve ever compiled a climate record for the past 2,000 years, your name is probably there. These folks are thorough.

Continue reading "More for the annals of climate misinformation " »

Posted by Olive Heffernan on August 19, 2008
Categories: Alicia Newton, Attribution, Climate Science, Communicating Climate Change | Permalink | Comments (38) | TrackBacks (0)

Andrew Revkin of the New York Times has been wondering whether climatologists could help turn down the “rhetorical noise” on recent temperature trends:

Given how much yelling takes place on the Internet, talk radio, and elsewhere over short-term cool and hot spells in relation to global warming, I wanted to find out whether anyone had generated a decent decades-long graph of global temperature trends accounting for, and erasing, the short-term up-and-down flickers from the cyclical shift in the tropical Pacific Ocean known as the El Niño - Southern Oscillation, or ENSO, cycle.

He queried Gavin Schmidt at RealClimate, who’s pondered how to reduce the noise (and beat the rhetoric) on climate trends before. Schmidt thought of the recent Nature paper in which David Thompson et al. removed ENSO fluctuations from the sea surface temperature record (and uncovered an abrupt 1945 temperature drop that they traced to buckets used to collect seawater after World War II).

Continue reading "The global warming signal minus the El Niño noise" »

Posted by Anna Barnett on July 10, 2008
Categories: Anna Barnett, Attribution, Climate Science, Climate variability, Uncertainty | Permalink | Comments (1) | TrackBacks (0)

“People are broadly concerned, but not entirely convinced”, concludes the latest poll on public opinion of global warming by social marketing group Ipsos Mori.

Despite the deluge of media reports in the last year documenting the scientific consensus on climate change and the startling rapidity at which impacts are being seen around the world - most notably perhaps the ever-decreasing Arctic sea ice - 60% of the British Public is uncertain that climate change is caused by humans, and many others believe that scientists are overstating the problem.

Writing in Sunday’s Observer, Juliette Jowit provides the following explanation:

There is growing concern that an economic depression and rising fuel and food prices are denting public interest in environmental issues. Some environmentalists blame the public's doubts on last year's Channel 4 documentary The Great Global Warming Swindle, and on recent books, including one by Lord Lawson, the former Chancellor, that question the consensus on climate change.

While it’s reassuring to know that the public questions the status quo, if Jowitt is correct, what’s frustrating is the ability of blatantly misrepresentative arguments to sway public opinion.

The Great Global Warming Swindle resulted in a record 250 complaints to regulatory watchdog Ofcom (including the first ever peer reviewed complaint), but that’s still a fraction of the 2.5 million viewers. Like many of those who saw the Channel 4 documentary, readers of Lawson’s offering on climate change ‘An Appeal to Reason’ are probably unaware it has been scientifically discredited in almost every review, including one on Nature Reports Climate Change by Sir John Houghton, Honorary Scientist at the UK’s Hadley Centre.

As Sir Houghton writes:

Promised as a "rare breath of intellectual rigour" and a "hard headed examination of the realities" of climate change, this offering is neither cool nor rational….and is largely one of misleading messages.

Lawson’s fundamental misunderstanding of basic scientific concepts is first displayed in his interpretation of the temperature records for the first part of this century, with which he attempts to discredit the science of climate change, and the work of many thousands of researchers who’ve dedicated entire careers to the problem. More recently, he repeats this in an amusing attack on the recent Nature paper by NASA’s Cynthia Rosenzweig.

Writing as a guest over on Susan Hills’ blog, Lawson’s piece starts off with a failure to grasp the term 'meta-analysis' – he clearly thinks that this is merely a lumping together of existing data. On the contrary, Rosenzweig and colleagues have used a powerful scientific tool to analyze changes in early 30,000 phenomena in the natural world - no mean feat - and in doing so, have shown that warming is aready having a worldwide impacts.

As Houghton rightly points out, Lawson is in need of climate science 101. But then, it seems, he's not alone - at least on that count.

Olive Heffernan

Posted by Olive Heffernan on June 24, 2008
Categories: Adaptation, Climate Policy, Climate Science, Communicating Climate Change, Features, In the News, Mitigation, Olive Heffernan, Opinion, Reviews | Permalink | Comments (17) | TrackBacks (0)

For all tree huggers out there, this week’s Science is dedicated to ‘forests in flux’, paying tribute to the trees and their contribution to the greater good. A special collection of articles in print, with complementary and online material, examines the fate of the world’s forests, in the face of climate change and an escalating human population.

If it’s been a while since you’ve had the chance to appreciate the languid leafiness of forest foliage, check out the online video. Or for those of you hoping for a more ‘hands on’ experience, there’s a whole section of Science Careers dedicated to opportunities in forest ecology.

There’s lots of serious science, with six Perspectives and one Review by researchers from all over the globe who give their tuppence worth on what’s needed to better understand forests and manage them properly.

Of particular relevance to discussions on how forests can mitigate global warming, Lera Miles and Valerie Kapos have a Perspective highlighting the risks involved in proposed schemes such as REDD (reduced emissions from deforestation and forest degradation) and how to minimize them. Also on this topic, Josep Canadell and Michael Raupach write on what science currently tells us is the best way to manage forests for sequestering carbon.

Drew Purves and Stephen Pacala discuss how forest dynamics remain one of the largest uncertainties in predicting future climate change and detail some of the efforts underway to improve their representation in models. Or for a really solid review of how forests affect climate change, check out Gordan Bonan’s piece here.

Or if that seems like a lot of tree pulp to get through, here are some interesting stats from the issue:

Forests cover ~42 million km2 in tropical, temperate, and boreal lands, and cover ~30% of the land surface

They store ~45% of terrestrial carbon and account for ~50% of terrestrial net primary production.

Forests hold more than double the amount of carbon in the atmosphere.

Carbon uptake by forests in the 1990s contributed to ~33% of anthropogenic carbon emission from fossil fuel and landuse change.

Olive Heffernan

Image: Plantations of Pinus radiata and Eucalyptus nitens in Gippsland (Victoria, Australia); courtesy of Michael Ryan.

Posted by Olive Heffernan on June 13, 2008
Categories: Biodiversity and Ecology, Biosphere feedbacks, Carbon markets, Climate Policy, Climate Science, Climate prediction, Deforestation, GHG emissions, Mitigation, Olive Heffernan, Uncertainty | Permalink | Comments (1) | TrackBacks (0)

The 20th century warming trend is not a linear affair. The iconic climate curve, a combination of observed land and ocean temperatures, has quite a few ups and downs, most of which climate scientists can easily associate with natural phenomena such as large volcanic eruptions or El Nino events.

But one such peak has confused them a hell of a lot. The sharp drop in 1945 by around 0.3 °C - no less than 40% of the century-long upward trend in global mean temperature - seemed inexplicable There was no major eruption at the time, nor is anything known of a massive El Nino that could have caused the abrupt drop in sea surface temperatures. The nuclear explosions over Hiroshima and Nagasaki are estimated to have had little effect on global mean temperature. Besides, the drop is only apparent in ocean data, but not in land measurements.

Now scientists have found – not without relief - that they have been fooled by a mirage.

The mysterious post-war ocean cooling is a glitch, a US-British team reports in a paper in this week’s Nature. What most climate researchers were convinced was real is in fact “the result of uncorrected instrumental biases in the sea surface temperature record,” they write. Here is an editor’s summary.

Continue reading "Post-World War II cooling a mirage" »

Posted by Quirin Schiermeier on May 29, 2008
Categories: Climate Science, Climate variability, Quirin Schiermeier | Permalink | Comments (7) | TrackBacks (2)

A new study, published online Sunday by Nature Geoscience, presents solid evidence that temperatures in the Earth's lower atmosphere are increasing in line with temperature changes on the ground.

This issue has been hotly disputed in the past, partly owing to the fact that temperatures measured in the troposhere - the portion of the atmopshere stretching from 12 to 16 kilometeres above the Earth's surface - by satellites and weather balloons in the early 1990s didn't mirror the changes on the ground.

This fact was used as evidence against climate change, despite the fact that it has been long known that there were problems with the original data collection and analysis.

In the search for more accurate measurements, two scientients Robert Allen and Steven Sherwood of Yale University, have now developed a novel approach using wind rather than temperature data. Their research shows that the lower atmosphere has indeed warmed since 1970, as projected by most climate models, and in sync with warming on the ground measured using temperature data.

In a related News and Views article, aslo on Nature Geoscience, Peter Thorn of the UK Met Office Hadley Centre, one of the world's premier climate modelling facilities, writes:

This is not simply an interesting academic aside — not knowing where observational problems begin and modelling limitations end undermines our ability to understand and predict global climate change.

For further reading on the topic, check out the post over on Real Climate last week discussing the same issue, and highlighting some upcoming papers in the Journal of Climate.

Olive Heffernan

Posted by Olive Heffernan on May 27, 2008
Categories: Atmospheric Science, Climate Science, Climate prediction, Features, Journal Club, Olive Heffernan | Permalink | Comments (1) | TrackBacks (0)

Isotope chemistry is a bit of an arcane world for the non-initiated. But variants of elements that differ only in the number of neutrons in their nuclei are common tools of the trade of archaeologists, geologists and climate researchers.

In the past 50 years, a much-improved chronology of past climatic events has evolved through analyses of the oxygen isotope record of marine shells and minerals in deep-sea and lake sediments. But information about the Earth’s deep geological past, in particular concerning the chemical composition of the atmosphere, is still hard to get by.

The debut of a new stable mineral-isotope proxy for ancient atmospheric condition is therefore a remarkable event, the editors of a paper in this week’s Nature note in their summary.

When analysing the triple oxygen isotope composition of ancient sulphate deposits, a team of geophysicists led by Huiming Bao of Louisiana State University found that they exhibit variable negative oxygen-17 anomalies over the past 750 million years. They propose that these small anomalies, first noticed a few years ago in a study unrelated to atmospheric chemistry, reflect those of atmospheric oxygen and carbon dioxide in the past.

The new proxy is hardly sensitive enough to record the relatively subtle variations in atmospheric oxygen and carbon dioxide content during the Pleistocene, the Earth’s recent period of repeated glaciations.

It could be useful, though, when evaluating extreme climates much earlier in our planet’s history. For example, oxygen-17 anomalies in barite sulphates display a negative spike – hinting at an extremely high level of atmospheric carbon dioxide - around 635 million years ago, when the Earth was likely recovering from a period of global glaciation in the Early Cambrian. This finding supports the not undisputed ‘snowball’ Earth hypothesis and/or massive methane release in the aftermath of Neoproterozoic glaciation

Quirin Schiermeier

Posted by Quirin Schiermeier on May 22, 2008
Categories: Atmospheric Science, Climate Science, Palaeoclimate, Quirin Schiermeier | Permalink | Comments (0) | TrackBacks (0)

Hurricanes may become rarer in the Atlantic throughout the 21st century if the world continues to warm, suggests a new study. The research is the latest to address the question of how – and whether - global warming will affect the intensity and frequency of hurricanes.

Globally, the number of major hurricanes has shot up by 75% since 1970. And although rising ocean temperatures are generally accepted as the key culprit – hurricanes can only form where sea surface temperatures exceed 26ºC - the link to global warming has remained a contentious issue.

In the new study, published online yesterday in Nature Geoscience [subscription], Thomas Knutson of the US National Oceanic and Atmospheric Administration and colleagues showed, using a regional climate model of the Atlantic basin, that the trend in increased hurricane activity in the Atlantic over the past 25 years will not continue into the future, though hurricanes in the area may become more intense and associated with heavier rainfall.

Though they use a different model, the results generally concur with the recent paper by hurricane specialist Kerry Emanuel, which shows that hurricanes are likely to decrease in frequency but increase in intensity in certain locations as temperatures rise.

I’ve written the full story here for Nature News.

Olive Heffernan

Image: NASA / Univ. Wisconsin-Madison

Posted by Olive Heffernan on May 19, 2008
Categories: Climate Science, Extreme Events, Features, Hurricanes, In the News, Journal Club, Olive Heffernan | Permalink | Comments (2) | TrackBacks (0)

Nearly 30,000 phenomena in the natural world - from the timing of plant flowering to the rate of ice melting - are being influenced by human-induced global warming, according to the first study to formally link trends in biological and physical systems to rising greenhouse gas emissions.

Led by Cynthia Rosenzweig of NASA's Goddard Institute for Space Studies in New York, the analysis, published in this week's Nature, brings together data from numerous different studies stretching back to 1970 to gain a big picture view of how climate change is impacting the planet.

Although the latest report from the Intergovernmental Panel on Climate Change (IPCC) concluded that human-induced climate warming is "likely" to have had a discernible effect on physical and biological systems, attributing such changes in natural systems to specific causes in notoriously difficult, as highlighted in the related News and Views article by Francis Zweirs and Gabriele Hegerl, both IPCC panelists.

Rosenzweig and collaborators made this link first by mapping changes in global average suface temperature between 1970 and 2004. They then looked at whether changes in natural phenomena in each region were consistent with warming or inconsistent with warming e.g. earlier blooming of flowers would be expected in a warmer climate.

In more than 90% of cases where there was a trend, it was consistent with the predicted effects of a warming world. As Emma Marris points out in an online news story, the bulk of the data come from Europe and several hundred more come from elsewhere in the world, but Africa, Australia and Latin America are poorly represented.

Olive Heffernan

Image credit: David Inouye

Posted by Olive Heffernan on May 15, 2008
Categories: Attribution, Biodiversity and Ecology, Climate Science, Features, In the News, Journal Club, Olive Heffernan | Permalink | Comments (1) | TrackBacks (0)

The Earth’s greenhouse history of the last 800,000 years is an open book now, thanks to years of detective work by two large international teams of climate scientists.

Nature has two papers this week, here and here, about the levels of atmospheric concentration of the two main greenhouse gases – carbon dioxide and methane – as derived from air entrapped in the EPICA Dome C ice core from Antarctica. Here is an editor's summary.

The first and foremost results: The present day concentration of both gases is higher than has ever been the case in the past 800,000 years. Also, the ups and downs in carbon dioxide and methane curves follows the succession of cold glacial climates and relatively warm periods (such as ours) in between. An 800,000 year temperature record had been reconstructed previously from Antarctic ice cores.

Together, the results provide powerful evidence for a strong link between greenhouse gases and climate. During most of the Earth’s history greenhouse gas concentrations have fluctuated in the absence of humans burning coal and other fossil fuels. But the unprecedented rise of greenhouse gases in the modern atmosphere, to concentrations which threaten to unhinge vital components of the Earth’s climate system, is clearly the result of human activity.

In the past, greenhouse gas concentrations have varied owing to subtle feedbacks between orbital changes and oceanic and terrestrial carbon cylcles. Carbon dioxide concentrations depend on oceanic uptake, whereas methane is linked with the size and distribution of wetlands releasing the gas.

Like all good science, the new data will raise many new questions. One is why the amplitude of the 100,000-year oscillation in methane and carbon dioxide concentrations (which correlates with the 100,000 year temperature cycle) has changes so markedly around 450,000 years ago. Warm periods in the more recent history of the Earth seem to have been warmer than the interglacials prior to 450,000 years ago. Carbon dioxide and methane concentrations mirror this trend, which might hint to the existence of a longer-term cycle not visible in the existing record.

Another question is how greenhouse gas concentrations measured in Antarctic ice cores relate to episodes of rapid warming and cooling in Greenland and the northern hemisphere. It seems that more that 70 such temperature jumps, perhaps as a result of changes in ocean circulation, have occured over the last 800,000 years.

“These new benchmark data for greenhouse-gas variability pose questions as to what a much longer record might show,” writes Ed Brook in a news and views article. The search for the best drilling site which could produce such a record is beginning.

Quirin Schiermeier

Posted by Quirin Schiermeier on May 15, 2008
Categories: Climate Science, Climate variability, Features, Journal Club, Palaeoclimate, Quirin Schiermeier | Permalink | Comments (0) | TrackBacks (0)

While most Londoners spent last week maximising their time spent basking in the glorious sunshine that so rarely comes our way, I spent it largely indoors - at a place that predicts these sorts of unusual occurrences, otherwise known as the European Centre for Medium Range Weather Forecasts (ECMWF) in Reading.

The World Modelling Summit for Climate Prediction held there last week was itself something of a rare event – a union of the weather and climate communities, who met to discuss whether – and how – they can eventually provide climate predictions that are as useful, and as useable, as weather forecasts.

The four-day summit culminated in a call for a massive investment, around a billion dollars, to fund a new global research facility or facilities with computer and research resources that would ‘revolutionize’ climate modelling capabilities, bringing into view the holy grail of ‘seamless’ weather-to-climate prediction.

We’ve covered the summit in some detail in this week’s Nature [subscription], in my news story and an editorial by Oliver Morton.

In short, the idea is that an injection of cash on this scale could bring about a quantum leap in climate simulations by funding climate computers far beyond those in use today. Currently, computers used for modelling the climate are in the 10-teraflop range, which means that they operate at inconceivably high speeds and run models that divide the globe into 100 kilometre cells to roughly project how global climate is likely to change in the long-term.

Though these models have had a key role in warning us of the gradual warming of our planet, they’ve fared pretty poorly when it comes to gauging the likelihood of extreme localised events, such as flooding or more frequent hurricanes. But scientists at the conference said that if they had access to supercomputers – with speeds in the range of hundreds of petaflops (basically 10,000 times more processing power) - they could resolve climate globally on the scale of kilometres, potentially creating models good enough to inform nations of the specific regional challenges they can expect in adapting to climate change.

Continue reading "A revolution - for climate model evolution " »

Posted by Olive Heffernan on May 14, 2008
Categories: Climate Science, Climate prediction, Features, In the News, Journal Club, Olive Heffernan, Technology | Permalink | Comments (0) | TrackBacks (0)

One of the more irritating aspects, if you will, of global change is that air pollution has so far prevented the planet from warming more rapidly than it actually did. Clean air is of course a good thing. But reducing pollution might expose an as of yet ‘masked’ portion of global warming.

This could have a dramatic affect on the Amazon rainforest. A team led by Peter Cox of the University of Exeter, UK, reports in a paper in this week’s Nature that reductions in aerosol pollution will tremendously increase the risk of severe drought in the Amazon region. Here is an editor’s summary of the paper.

Although it accounts for nearly a quarter of the world's fresh water, drought is not unknown in Amazonia.

In the dry season, from July to October, rainfall in the region is linked to sea surface temperatures (SST) in the tropical Atlantic. In years with a pronounced temperature gradient - warming of the tropical Atlantic north of the equator relative to the south – the normal’ position of high and low atmospheric pressure systems can shift, delaying or suppressing the onset of the South American monsoon.

The effect has been observed in 2005, when large parts of the Amazon region were hit by the worst drought in decades. See a Nature news story by Mike Hopkin here (subscription required) and a New York Times story here about the devastating event.

Cox thinks that the 2005 drought was a harbinger of things to come. Their “simulations for the 21st century show a strong tendency for the SST conditions associated with the 2005 drought to become much more common, owing to continuing reductions in reflective aerosol pollution in the Northern Hemisphere.”

Droughts like in 2005 will happen every two years by 2025, and in nine out of ten years by 2060, the model suggests.

How robust is this dire prediction? The Amazonian climate, for reasons not quite understood, is notoriously difficult to simulate. But the Hadley Centre’s climate model which was used for this study has previously reproduced features of the regional climate with greater accuracy than other models.

In Mike Hopkin's words, “the ultimate fear is that the Amazon forest - often touted as an invaluable piece of armour against climate change - could become part of the problem rather than a key element of the solution. Droughts make it more likely that it will become a net source of greenhouse gases to the atmosphere, rather than mopping them up.”

Quirin Schiermeier

You can vote or comment on the importance of the new paper in the Journal Club of Nature Reports Climate Change.

Posted by Quirin Schiermeier on May 08, 2008
Categories: Biosphere feedbacks, Climate Science, Climate prediction, Extreme Events, Quirin Schiermeier, Topics | Permalink | Comments (5) | TrackBacks (0)

A paper in this week’s Nature predicts that, rather than warming, North Atlantic sea surface temperatures may actually decrease slightly in the next decade. What’s more, the paper suggests global surface temperatures may not actually increase either.

Has global warming stopped? Is this a nail in Al Gore’s coffin?

Well, no.

Despite headlines such as ‘Doubt is cast over global warming’ and ‘Global warming could stop NATURALLY for ten years, say scientists’ that is not what this paper is about.

What this new paper by Noel Keenlyside, of the Leibniz Institute of Marine Sciences in Germany, sets out to do is incorporate data on short term variations in climate into our models of climate change. By doing this they push us into the arena of creating shorter term predictions, in this case of the next decade.

In a “News and Views” commentary on the piece in the same issue of Nature Richard Wood explains:

Keenlyside and colleagues’ model uses a very simple ocean initialization method in which they add heat to or remove it from the ocean surface until sea surface temperatures across the globe are close to observed values. They use their model to produce a set of retrospective ‘forecasts’ starting from earlier states, which they test against what actually happened. Their system produces refined temperature predictions a decade ahead for large parts of Europe and North America.

Whether their prediction of a plateau for warming for a decade in North America and Europe is correct or not, their research may signal a shift that many climate researchers have been calling for for awhile now — toward service-oriented climate science ...

I am sure that this is an excellent paper by world class scientists. But when I look at the broader significance of the paper what I see is that there is in fact nothing that can be observed in the climate system that would be inconsistent with climate model predictions. If global cooling over the next few decades is consistent with model predictions, then so too is pretty much anything and everything under the sun.

Cross posted by Daniel Cressey on The Great Beyond

Posted by Olive Heffernan on May 01, 2008
Categories: Climate Science, Climate prediction, Climate variability, Daniel Cressey, In the News | Permalink | Comments (8) | TrackBacks (0)

A paper in Nature Geoscience this week (subscription required) serves up an important figure for climate modellers: the size of the greenhouse effect caused by ozone near the Earth's surface, estimated from direct observations.

Whereas 20 years ago the discovery that the stratospheric ozone layer was thinning led to international prohibitions on ozone-eating chemicals, this new study reflects concerns about excess ozone produced nearer to the ground, in the troposphere, by reacting pollutants. Tropospheric ozone is a greenhouse gas - and although carbon dioxide still gets the most column inches, other greenhouse gases such as ozone (see also methane) are drawing more and more scientific attention.

Previously, the best estimates of the radiative forcing from ozone - its planet-warming power - came from simulations. The latest IPCC report used several such models to assess forcing from anthropogenic ozone alone, excluding ozone from natural sources, and came up with a range of values from 0.25 to 0.65 watts per square metre (in comparison, forcing by all anthropogenic greenhouse gases together was estimated at 1.6 watts per square metre). Now, NASA's Aura satellite has collected enough measurements of infrared radiation and ozone thickness in cloudless patches of sky to pin down the combined effects of natural and human-produced ozone. According to these data, the global average forcing in the year 2006 was 0.48 (+/- 0.14) watts per square metre. No surprises, but a palpable step forward in the hardworking and sometimes underappreciated field of Earth observation.

Anna Barnett

Image: Artist's rendering of Aura satellite, NASA

Posted by Anna Barnett on April 24, 2008
Categories: Anna Barnett, Atmospheric Science, Climate Science | Permalink | Comments (1) | TrackBacks (0)

The current issue of Nature has a feature about the state of the Greenland ice sheet (See also the related editorial dealing with the state of polar research funding).

I got started on this story at the American Geophysical Union meeting last December, in which session after session presented new data about the extent of summer melt in Greenland. Information from the GRACE satellites shows that the overall mass balance of the ice sheet is dropping steadily, and although surface melt varies quite a bit from summer to summer, two of the last three years have seen record levels of melt.

“2007 was a shocking year,” Scott Luthcke, who works with GRACE at NASA’s Goddard Space Flight Center in Maryland, told me later.

One record melt season does not spell the end of Greenland, of course, and journalists must always be wary about sounding too alarmist based on short-term records. But overall, the outlook for Greenland is simply not good: Changes in speeds of the island’s outlet glaciers show that, no matter whether they are advancing or retreating, they are far faster at changing their behavior than anyone had thought before.

As the article was going to press, we learned that another pair of key Greenland papers would appear the next day online in Science. Such is the peril of scheduling features far in advance while knowing your competitor journal has interesting papers under review.

The basic point of the two new papers -- that vast quantities of meltwater can form and then drain away atop the ice sheet each summer – made it into my feature anyway. But if you want more details, check out the original papers at the Science Express website. One paper, with lead author Sarah Das of the Woods Hole Oceanographic Institution, reports on a 4-kilometre-long melt lake that vanished into the ice sheet within the space of two hours. The other, with lead author Ian Joughin of the University of Washington’s Applied Physics Laboratory, describes seasonal speed-up in ice flow along Greenland’s western flank – though not so much in the outlet glaciers. Together, the papers confirm how meltwater likely helps lubricate the slippage of the ice sheet towards the ocean.

If you’re still looking for more things Greenland, check out the recent posting on RealClimate that again suggests the details of how Greenland melts are more complicated than we thought.

And if you just need a fix of gorgeous Greenland pictures, click on over to the Extreme Ice Survey project of photographer James Balog and others. We used only one of Balog’s iceberg images in my Nature feature, but his time-lapse work of melting glaciers is stunning.

Alexandra Witze

Image credit: NASA/GSFC VISUALISATION STUDIO; SOURCE: S. LUTHCKE

Posted by Olive Heffernan on April 22, 2008
Categories: Alex Witze, Climate Science, Cryosphere, Features, In the News | Permalink | Comments (4) | TrackBacks (0)

The North Atlantic Ocean may still be an active storehouse for atmospheric carbon dioxide, said scientists at the European Geosciences Union here in Vienna yesterday.

Following evidence published last year showing that both the Southern Ocean and North Atlantic Ocean have weakened as carbon sinks in the past two decades, the new results suggest that the trend has recently reversed in the North Atlantic.

Scientists have feared that the weakening trend could be a long-term impact of global warming and that it could be typical of the ocean as a whole, which absorbs an estimated 25 per cent of anthropogenic carbon dioxide emissions yearly. If the ocean switches from a storehouse to a source of the greenhouse gas, this would jeopardise efforts to stabilise atmospheric greenhouse gas levels.

Speaking at a press conference at the EGU assembly yesterday, Ute Schuster from the University of East Anglia in Norwich, UK and Christoph Heinze at the University of Bergen, Norway, presented the results of a yearly analysis of carbon dioxide fluxes across the North Atlantic Ocean.

Previously, Schuster and colleagues showed that carbon uptake by the North Atlantic had halved between the mid-1990s and the early 21st century. But further analysis of the data on a year-by-year basis has shown that the uptake of carbon dioxide in the region has been increasing since 2002 and showed an even greater increase, relative to the early 2000s, in 2005.

The researchers caution that the results are preliminary and are not yet published. The coverage was poor in 2006 and they have not yet finished the analyses for 2007, but they say that the results so far indicate that the trend in weakening of the North Atlantic carbon sink is not linear.

The reasons for this variation are unclear. “I personally think we can’t say with confidence that the trend [in weakening sinks] is attributable to [anthropogenic] climate change”, says Schuster. Surface circulation in the North Atlantic has changed in recent years, she says, but these changes could be due to natural climate variability. Specifically, the North Atlantic Oscillation, a large-scale atmospheric pattern that has important impacts on European climate, could be influencing the rate of carbon dioxide uptake.

Continue reading "EGU: North Atlantic Ocean may regain status as carbon sink" »

Posted by Olive Heffernan on April 17, 2008
Categories: Biosphere feedbacks, Climate Science, Conferences and Meetings, EGU 2008, Ocean science, Olive Heffernan | Permalink | Comments (0) | TrackBacks (0)

The dizzying economic growth in Asia threatens to disappoint expectations that new technologies will provide an easy fix for our climate problem, warn the authors of a commentary article in Nature this week.
Roger Pielke, Tom Wigley and Christopher Green believe that the Intergovernmental Panel on Change Change, which was awarded the Nobel Peace Prize last year for its work, plays “a risky game” when assuming that “spontaneous advances in technological innovation will carry out most of the burden of achieving future emissions reductions.”

Most of the emissions scenarios that the IPCC considered for its last report include significant ‘built-in’ technological change. In other words, the IPCC assumes that a good deal of climate-friendly innovation will happen spontaneously, in the absence of climate policy measures.

Now, necessity, economic growth and pursuit of profit do generate all kinds of more or less useful new technologies, from atomic bombs to iPods. But assuming that pure market forces will readily come to our aid in matters of climate change might be too optimistic, the commentary authors warn. Worse, they say, the assumption of a lot of spontaneous technological change could be misinterpreted as a license for policymakers not to take aggressive action.

Pielke, Wigley and Green have stirred up a hornets’ nest with their analysis. Some initial reactions to their call to arms are collected in an accompanying news piece. Expert opinions range from “overdue” to “totally misleading”.

So who’s right and who’s wrong, then? Are we dramatically underestimating the challenge of climate change? Or is this just one more twist exercised to unnecessarily dramatize an admittedly serious problem? Or is it all just shadow-boxing in the arcane world of scenario-making?

Economics of climate change are a politicized field. Depending on one’s standpoint (on what market forces can or cannot do, for example), one may find different answers to these questions. Less disputable is the fact that some two billion people in China and India are on the point of adapting to western living standards. Their consumptive power and increasing mobility will add to the global climate and energy problem. Let’s hope that their creativity and engineering skills will also add to its solution.

Quirin Schiermeier

Illustration: B. Mellor

Posted by Anna Barnett on March 31, 2008
Categories: Climate Science, Quirin Schiermeier, Technology | Permalink | Comments (9) | TrackBacks (0)

In a Science paper last year (subscription required), Rahmstorf et al. pointed to 2001-2006 measurements of global temperature at the top end of the IPCC's 2001 projections - and global sea level rise well beyond the range predicted in 2001 - as evidence that "the climate system, in particular sea level, may be responding more quickly to climate change than our current generation of models indicates." Today in a letter to Nature Geoscience (subscription required), Roger Pielke, Jr, questions whether models from that 2001 generation improve on the predictive power of their forbears.

Pielke checks predictions from all four IPCC reports, dating back to 1990, against reality. Each report made a series of 'if-then' statements about the likely results of various emissions scenarios; in hindsight, Pielke can pick out which of these possible greenhouse experiments has actually been running on Earth since 1990 and compare the results to the IPCC's shifting hypotheses.

Whereas the 2001 projections undershot the observed temperatures and sea levels, the 1990 projections overshot them, he concludes. Projections of temperature and sea level fell substantially between the 1990 and 1995 IPCC reports, when aerosols were added to models and carbon-cycle simulations were tweaked. But because they dropped too far, the adjusted post-1995 projections "are not obviously superior in capturing climate evolution", says Pielke.

That's not to say that 2001 models were no better than those a decade older. Including more information has made recent simulations more sophisticated - but so far it hasn't much improved their ability to sketch out future climates, probably because important factors are still missing. Predictions from the two most recent reports do, however, seem to have crept toward the actual climate evolution, and additional rounds of of refinements may help the models to home in further.

Anna Barnett

Posted by Anna Barnett on March 31, 2008
Categories: Anna Barnett, Climate Science, Climate prediction | Permalink | Comments (7) | TrackBacks (0)

The Guardian was far from alone in reporting this week that "A vast hunk of floating ice has broken away from the Antarctic peninsula, threatening the collapse of a much larger ice shelf behind it, in a development that has shocked climate scientists." On The Great Beyond, Quirin Schiermeier points out that the the most noteworthy thing about this delicately poised hunk of the Wilkins ice shelf may be its media visibility: the loss of a 400-square-kilometre piece of the same shelf earlier this year received no such fanfare.

Still, that visibility is pretty spectacular. Check out this mashup of the Twin Otter plane's flyover footage with the satellite images that tipped off British Antarctic Survey scientists:

"The ice shelf is hanging by a thread," said David Vaughan of the British Antarctic Survey. "We'll know in the next few days or weeks what its fate will be."

Anna Barnett

Posted by Anna Barnett on March 28, 2008
Categories: Anna Barnett, Climate Science, Cryosphere, In the News | Permalink | Comments (3) | TrackBacks (0)

On Nature Reports Climate Change , Gywn Prins of the LSE has reviewed The Hot Topic by science writer (and once climate change editor at Nature) Gabrielle Walker and former UK chief science advisor Sir David King.

The book has with the odd exception, received mostly favourable - and a few oustanding reviews - namely Chris Mooney's for New Scientist and Dave Reay's in the March 6 issue of Nature.

Indeed, Reay compares it Rachel Carson’s celebrated Silent Spring in its ability to engage millions and commends its even-handed coverage of the ‘climate debate’. Reay writes:

The Hot Topic has an authoritative clarity that scythes through the junk science and brushes aside the brigades of doom-mongers and overly earnest environmentalists.

Over on The Intersection Chris Mooney refers to it as "the best global warming book I've ever read", and has a similar stance to Reay. Of Walker and King, he writes:

Their overview of the science and policy of climate change is a model of clarity, comprehensiveness and, above all, sanity. It truly does find a middle ground in the climate debate.

On the contrary, Prins (who authored a Commentary in Nature last year with Steve Rayner calling for a radical alternative to the Kyoto Protocol) argues that the book is both “troubling” and “relentlessly normative” in that it represents “an unquestioning acceptance of the received wisdom”.

Prins is especially disgruntled with how Walker and King, in his view, polarize perspectives on the way forward on climate policy:

[They] have no scintilla of doubt that the Kyoto Protocol is the road to follow and that anyone who deserts it is wrong and possibly corrupt. So we have as heroes the EU, which doesn't "duck" the problem, and as villains the US, languishing under the rule of "President Bush and his fiercely partisan advisers". They lump all "sceptics" — anyone who disagrees with them — together like the damned in a Hieronymus Bosch painting of heaven and hell.

He then compares The Hot Topic to Bjorn Lomborg’s The Skeptical Environmentalist (albeit at the other end of the polemical spectrum) in it’s treatment of uncongenial information, essentially making the point that the authors choose their supporting arguments carefully and disregard the rest.

Continue reading "Review of The Hot Topic: The road well travelled " »

Posted by Olive Heffernan on March 17, 2008
Categories: Climate Policy, Climate Science, Features, Olive Heffernan, Reviews | Permalink | Comments (1) | TrackBacks (0)

Historian Will Durant ... is said to have cautioned: "Civilization exists by geological consent, subject to change without notice."

This warning, re-broadcast in an essay by eminent public scientist Frank Press, wraps up an excellent special supplement on Earth science in this week's Nature. In honor of the International Year of Planet Earth, the supplement features more than a dozen in-depth commentaries on current topics in geoscience, almost all looking warily toward past, present and future climate change (with or without notice).

As an overview of several leading-edge climate science issues, it's well worth a look - and the thoughtful opening article on historical drivers of geoscientific progress is also not to be missed. Act now, because the entire supplement is currently free to access.

Anna Barnett

Photo: NASA

Posted by Anna Barnett on January 21, 2008
Categories: Anna Barnett, Climate Science | Permalink | Comments (0) | TrackBacks (0)

If you like coral reefs you should enjoy them while you can, they won’t be around for long. Global warming and the ocean acidification that comes with it will decimate reefs by the end of this century, according to a new review article in Science.

“The impact of climate change on coral reefs is much closer than we appreciated. It's just around the corner,” says study author Ove Hoegh-Guldberg, of the University of Queensland. “... The warmer and more acidic oceans caused by the rise of carbon dioxide from the burning of fossil fuels threaten to destroy coral reef ecosystems, exposing people to flooding, coastal erosion and the loss of food and income from reef-based fisheries and tourism. And this is happening just when many nations are hoping that these industries would allow them to alleviate their impoverished state.” (Reuters ... Telegraph)

Although there is no new original research here, when all the numbers are brought together they are pretty frightening. Atmospheric carbon dioxide will exceed 500 parts per million sometime between 2050 and 2100. This will drive global temperatures up at least 2°C, “values that significantly exceed those of at least the past 420,000 years during which most extant marine organisms evolved” says the paper.

It adds ominously, “Under these conditions, reefs will become rapidly eroding rubble banks such as those seen in some inshore regions of the Great Barrier Reef, where dense populations of corals have vanished over the past 50 to 100 years.”

This year marks not only the release of a clarion IPCC report and the convening of an enormous UN climate conference, but also the 50th anniversary of the Keeling curve -- the longest continuous recording of atmospheric carbon dioxide levels, revealing a gradually rising carbon dioxide profile that helped trigger early concern about global warming. As part of this week's Earth Observation special (subscription required), Nature has a commentary by Euan Nisbet, atmospheric scientist at Royal Holloway, on the Keeling curve -- which "ranks very high indeed among the achievements of twentieth-century science", he says -- and similar studies in the field of Earth monitoring. Nisbet writes:

Monitoring is science's Cinderella, unloved and poorly paid. Sustaining a long-term, ground-based programme that demands high analytical standards remains challenging. Funding agencies are seduced either by 'pure' notions of basic science as hypothesis-testing, or by the satanic mills of commercial reward. Neither motive fosters 'dull' monitoring because meeting severe analytical demands is not seen as a worthwhile investment. At one stage, Keeling was ordered to guarantee two discoveries per year and today, modern research has become a planned journey through set 'milestones' to deliverable destinations.

What do you think -- how important is this 'Cinderella science' to ongoing climate research and policy, and how could we secure reliable long-term support?

Image credit: Global Warming Art

Anna Barnett

Posted by Anna Barnett on December 05, 2007
Categories: Anna Barnett, Climate Science, GHG emissions, Opinion | Permalink | Comments (3) | TrackBacks (0)

Signs of a very different 21st-century climate are already showing up, and not just in the melting arctic. A new review in Nature Geoscience highlights reports that the boundaries of the tropics, defined by temperature, rainfall, wind, and ozone patterns, have shifted poleward by at least 2 degrees latitude in the last 25 years. According to climate models, that's as far as the tropical belt was supposed to creep by the end of this century. Five different methods used to measure the tropics all show more or less breakneck rates of expansion -- one gives as much as 4.8 degrees in 25 years.

Continue reading "Tropics expanding fast " »

Posted by Anna Barnett on December 04, 2007
Categories: Anna Barnett, Climate Science, Extreme Events | Permalink | Comments (1) | TrackBacks (0)

Those bored of playing with Google Earth may be interested in NASA’s new toy – a stunningly detailed map of Antarctica. Claiming to be ten times more detailed than previously available equivalents, the map was painstakingly constructed by the stitching together of 1,100 hand-selected photos from Landsat satellites (NASA press release).

The map was produced in collaboration with the National Science Foundation and the British Antarctic Survey. It’s already attracting media attention (BBC, Bloomberg, ABC, Herald Sun, Wired).

“This innovation, compared to what we had available most recently, is like watching the most spectacular high-definition TV in living colour versus watching the picture on a small black-and-white television,” says Robert Bindschadler, chief scientist of the Hydrospheric and Biospheric Sciences Laboratory at Goddard (NSF press release).

Those who sifted through all the photos and put them together are hoping that the Landsat Image Mosaic of Antarctica will be rather more than a fun distraction for desk workers avoiding work.

“...LIMA is also a fundamental tool for scientists,” says Scott Borg, director of NSF's division of Antarctic sciences. “It will be used in every discipline from biology to geology to glaciology, both to answer scientific questions and plan fieldwork in the vast unexplored tracts of Antarctica. For educators, students, and the general public, LIMA will bring to life the Antarctic continent like nothing before it.”

The images will apparently eventually make their way to Google Earth, but why wait for that – the map is online now.

Images: top – mosaic of Antarctic shots, bottom – diagram of photos used in LIMA / all courtesy of NASA

Cross-posted from Daniel Cressey on The Great Beyond.

Posted by Anna Barnett on November 28, 2007
Categories: Climate Science, Daniel Cressey | Permalink | Comments (0) | TrackBacks (0)

World experts have gathered in Valencia to produce a synthesis of all the Intergovernmental Panel on Climate Change reports released to date (Nature – subscription required). Thus, there is a rash of climate change news.

The Valencia meeting’s report will, according to AFP, “serve as a guide for policymakers for years to come”. Now traditional arguments between Europe, the US and other participants over the exact wordings are already underway (AP).

Even OPEC is getting in on the action. The group of oil producing nations said this week it would assist in cutting or capturing carbon emissions (Reuters). Some reports even say it is mulling over the creation of a $3 billion fund invest in emission capture technology (Times).

In Australia the former head of the country’s Commonwealth Scientific and Research Organization’s atmospheric research unit warned before the meeting that current policy is based on science that is already out of date (ABC). “If you think climate change is on the agenda, just wait another couple of years,” he told the Sydney Morning Herald.

Cross posted from Daniel Cressey on The Great Beyond

Posted by Olive Heffernan on November 16, 2007
Categories: Climate Policy, Climate Science, Daniel Cressey, Features, In the News | Permalink | Comments (1) | TrackBacks (0)

Kevin Trenberth

The recent Asian Pacific Economic Cooperation (APEC) summit has brought further attention to climate change and what, if anything, to do about it. In spite of the IPCC findings that global warming is “unequivocal”, doubt remains in some quarters about the reality of climate change and the human cause. Issues are continually raised that have no basis, as highlighted by the recent Commentary from Syun-Ichi Akasofu in the Wall Street Journal.

Akasofu immediately starts out on the wrong foot by claiming there are two sides, those of believers and non-believers, but it is not a matter of belief, it is a matter of scientific facts! He further fails to understand the nature of the IPCC process and the extensive reviews in which all comments are addressed rigorously as the report is developed over three years. Contrary to the claim, there is no assumption by IPCC that recent warming was due to the increased greenhouse effect from increasing human produced carbon dioxide. Rather, climate models that run with and without the human-induced changes in atmospheric composition demonstrate that human warming has emerged from natural climate variability since about 1970.

Over the past 500,000 years or so, temperatures, carbon dioxide and methane have gone up and down more or less in tandem through the major ice ages and interglacial periods, as shown in ice cores. As detailed in a Real Climate blog post on this topic, in the absence of human intervention, these changes happen over time, but not at the rate at which CO2 is currently increasing in the atmosphere. Scientists know that carbon dioxide and methane changes follow rather than cause these changes in temperature between glacial periods, but they also know that these changes in greenhouse gases amplify a relatively weak forcing to help drive temperature change. To suggest otherwise, as Akasofu does, is misleading at best.

Akasofu then trots out the mistaken view that the “hockey stick” curve of temperatures over the past 1000 years showing an upward bend at the end has been discredited. In fact, it has been reinforced in the latest IPCC report, although it is given less emphasis as it is now backed up and confirmed by evidence from multiple independent studies.

He further claims that natural climate variations have been forgotten and attributes recent warming to the “rebounding effect from the little ice age”, but fails to realize that natural climate variability also has a cause. While it is true that we do not have the measurements to show what was happening in the ocean during this time, for instance, we have good reason to believe that natural internal variability played a role. To the extent that the "Little Ice Age" and "Medieval Warm Period" can be meaningfully defined, there has been much work showing that the main variations can be explained in terms of the response of the climate system to natural variability in solar and volcanic events that would have influenced surface temperature. And warm periods in the past, such as the warming in the Greenland region in the mid-twentieth century, were not global in contrast to recent warming, which is.

Climate models are not perfect, but they are useful tools for quantifying the effects of various climate processes and drivers of climate change. Akasofu decries the confused state of climatology, but it is he who is really confused, and his article only serves to confuse the general public. It is sad that a once distinguished newspaper published such misleading half-truths without verifying them.

Kevin Trenberth

Posted by Olive Heffernan on September 19, 2007
Categories: Climate Science, Communicating Climate Change, In the News, Kevin Trenberth | Permalink | Comments (39) | TrackBacks (0)

Kevin Trenberth

The situation on how hurricanes have changed and will likely change in the future are outlined in my recent Scientific American article, but may seem as murky as ever to the public although clarity is actually emerging.

A recent news report in the Press Register outlines some sources of confusion related to just how well the past record is known. It cites work by Landsea that relied on numbers of land-falling storms as a way to calibrate the Atlantic hurricane record, and which concluded that there may be an undercount of 3.2 storms per year prior to 1966. The most recent Eos Transactions has two articles that follow up and point out why use of land-falling storms is misleading [Holland 2007; Eos 88 (36) 348-349] and that the conclusions of increased activity do not change anyway [Mann et al., 2007; Eos 88 (36) 349-350].

The Holland article points out that there are good reasons why the fraction of storms making landfall should change, both because of natural variations and especially if the climate changes. The Mann et al. article adopts the Landsea-suggested changes for the past as a “what if” test and goes on to show that even a substantial underestimate of early 20th century storms does not change the significance of the increase in activity since 1994. Nor does it change the strong relationship with observed sea surface temperatures (SSTs) in the region; the SSTs have a much more reliable observational record and have clearly increased.

Surprisingly, none of these studies refers to what seems to me to be the most definitive analysis of the likely missed storms in the historical counts by Chang and Guo (2007) in which they analyze in detail the actual ship tracks in the past compared with modern tropical storm tracks. To quote their main conclusions: “It is estimated that the number of tropical cyclones not making landfall over any continent or the Caribbean may have been underestimated by up to 2.1 per year during 1904–1913, with this number decreasing to 1.0 per year or less during the 1920s and later decades. Our results suggest that the characteristics of North Atlantic tropical cyclone track statistics might have changed during the 20th century.”

In 2007 the tropical storm season has been fairly normal in many respects up to now. Only 3 hurricanes have been recorded (versus average 3 to 4) but two were category 5 storms, and that is highly unusual. Forecasts of hurricane activity by NOAA and Bill Gray continue to forecast substantially above normal activity in the Atlantic. To me, observing the events thus far, the incredibly intense convective activity in the Indian Ocean from May to July was an important and totally overlooked factor. The subsequent heavy rains and flooding in India and China were no doubt related. The fact that Atlantic hurricane activity is influenced by events in the Indian Ocean seems to be overlooked by the hurricane forecasters.

Kevin Trenberth

Posted by Olive Heffernan on September 17, 2007
Categories: Climate Science, Hurricanes, Kevin Trenberth | Permalink | Comments (3) | TrackBacks (0)

Just when everyone was getting sick of explaining that climate models are producing projections not predictions per se, it seems that some of them are indeed producing predictions. There's a paper (pdf) in Science from a team at the Hadley Center that shows how using real initial conditions improves the accuracy of ten year climate forecasts. They do a bit for hindcasting first, looking at historical data and comparing model runs with real initial conditions with run-of-the-mill runs. Then they do some prediction. This prediction is being treated as saying that we're at the end of a little plateau, and that at the end of this decade things will warm up further, giving a run of years in the early 2010s where the chances for new global records are good. Quirin Schiermeier wrote a story on this for news@nature, reporting that the modelling community seems pretty impressed. Here's a bunch more coverage (88 pieces at the time of googling), and for those with a subscription to Science here's the estimable Dick Kerr, who had longer to write the story than the rest of us...

Posted by Oliver Morton on August 10, 2007
Categories: Climate Science, Climate variability, Oliver Morton | Permalink | Comments (8) | TrackBacks (0)

Over at News@nature, Mike Hopkin reports from the Ecological Society of America's meeting in San Jose on research into tropical forest growth rates. Looking at plots in Panama and Malaysia, the researchers found that increases in mean daily minimum temperature over a couple of decades correlated with decreases in growth rates. They associate this with lower net photosynthetic activity.

The team, led by Harvard's Ken Feeley, suggests that if this sort of effect were repeated in bigger rainforests (most of which have only experienced marginal warming to date, as I understand it) then what are now stable stores of carbon would become net sources as theworld heats up. This is obviously a considerably less optimistic scenario than the possibility that carbon-dioxide fertilisation would make them sinks. It would presumably make the net effect of the increase in soil respiration that Peter Cox and others always stress (Nature paper from 2000) an even worse problem.

It's not a dead cert that the change is due to temperature -- the paper (published in Ecology Letters) seems to suggest that increased cloudiness could be playing a role. And there could be internal botanical changes too -- maybe the lianas are doing more damage? But all in all it doesn't sound good.

Mike is blogging the conference on the newsblog.

Posted by Oliver Morton on August 10, 2007
Categories: Biosphere feedbacks, Climate Science, Oliver Morton | Permalink | Comments (0) | TrackBacks (0)

Olive Heffernan

Much like the rest of Britain, I’m beginning to wonder if it’s ever going to stop raining. And despite feeling slightly miffed at an appalling excuse for a summer, I realise I'm lucky to be based in slightly soggy London, given that large areas of the country are currently besieged by some of the worst flooding in recent British history.

Calling it a ‘21st century catastrophe’, Michael McCarthy at the Independent writes that “Britain is suffering from a wholly new type of civil emergency: a disaster caused by 21st-century weather,” which has left more than a third of a million people without drinking water, nearly 50,000 people without power, thousands more people homeless and caused more than £2bn worth of damage so far.

Britain is not alone in experiencing extremely heavy rainfall. As reported on MSNBC, “parts of China had the heaviest rainfall since records began, killing more than 700 so far this year. Hundreds of thousands have been displaced by flash floods in southern Pakistan.”

While these single events cannot be attributed to climate change, many are questioning if the flash flooding is a sign of what is in store for the future. And scientists have some of the answers.

In a paper coming out in Nature this Thursday, Francis Zwiers of the Canadian Centre for Climate Modelling and Analysis in Toronto and colleagues present the first evidence that human-generated greenhouse gas emissions have altered rainfall patterns in the 20th Century. In the region between 40 and 70 degrees North, covering northern Europe, Russia and parts of North America, rainfall increased by 62 millimetres per century between 1925 and 1999. Zwiers and colleagues say that 50-85% of this increase can be attributed to human activity. For further discussion and comments on the paper, there’s a news story by my colleague Daniel Cressy on News@Nature. And it’s also been picked up by the BBC.

And a recent paper published in Science in June suggests that global warming may result in even more rainfall worldwide than is currently evident in climate model simulations. Frank J. Wentz of Remote Sensing Systems in Santa Rosa, California and co-workers compared global satellite data from 1987 to 2006 and found that rainfall increased at the same rate as atmospheric water vapour per degree Celsius of surface warming. Climate models had projected a dampened response of rainfall to global warming owing to a decrease in surface winds, but Wentz and colleagues found that surface winds have in fact become stronger, leading to heavier rainfall (more on this in Nature Reports Climate Change soon).

Coming back to Britain… the situation is likely to worsen over the next 24 hours. Eight severe warnings have been issued covering the rivers Thames, Severn and Ouse, in particular for towns such as Gloucester, Tewkesbury, Oxford, Abingdon, Reading and Bedford. Fifty other flood warnings are in place across England and Wales.

To see the areas generally most at risk of flooding in England and Wales, visit the Environment Agency’s flood map online, where you view flood risk by postcode. For an up to date interactive on the current situation, the Guardian has quite a snazzy interactive highlighting areas most at risk.

Olive Heffernan
News Editor
Nature Reports Climate Change

Posted by Olive Heffernan on July 24, 2007
Categories: Climate Science, Extreme Events, In the News, Olive Heffernan | Permalink | Comments (3) | TrackBacks (0)

Kevin Trenberth

A recent paper published by Gaertner et al. in Geophysical Research Letters (GRL) (in press as of 12 July 2007) explores the possibility for tropical cyclones to occur in the Mediterranean area in the future with global warming. It has been featured in the Times. The paper correctly points out that tropical cyclones have recently ventured into some unusual places with Catarina on the east coast of Brazil in March 2004 and Vince making landfall in Spain in 2005. Gaertner et al. use an ensemble of regional climate models to assess new locations of tropical cyclone occurrence. They find an increase in extremes of cyclone intensity over the Mediterranean Sea in regional model climate change scenario simulations. This increase, they claim, is clearly related to tropical cyclone formation, revealing for the first time a risk of tropical cyclone development over the Mediterranean Sea under future climate change conditions.

The regional model framework for this study is one limitation as it may not create the correct large-scale atmospheric circulation across the region. In particular, the Mediterranean climate in summer is one of clear skies and sunny days associated with the overall global monsoon circulation, such that the upward motion and rains in southern Asia are linked to the subsiding air over the Mediterranean that makes for a very stable environment unfavorable for storms. Unless that link is properly simulated (and it may not be, especially in a regional model) the vertical atmospheric temperature and wind structure are unlikely to be right.

The authors are aware of the summer difficulties and so they choose September as the time for the simulations. This has the advantage that the sea surface temperatures (SSTs) are highest then. The sun has been beating down all summer, but it tends to form a shallow layer of warm water and whether there is adequate heat below the surface is also a critical question. As cyclones form they churn up the ocean, bringing cold waters up from below and cool the ocean, creating a cold wake. In this work the SSTs were specified and fixed and this was not allowed to happen.

Moreover, by September, the mid-latitude westerlies have set in and the winds in the upper troposphere are typically over 20 m/s, so the wind shear environment is generally unfavorable for such storms. It is possible that the weather could change enough to relax the winds for just long enough to open a window for tropical cyclones but the odds are not high. This is the extratropics, after all.

All these questions remain. Nonetheless, with higher SSTs it does seem likely that cyclones would be more vigorous. But whether they are truly tropical or not is a key issue. The paper does not comment on water vapor: the Mediterranean Sea is surrounded by land where the air is drier and this can cause storms to run out of moisture and peter out. Nor does it mention rainfalls and flooding: a chief characteristic of tropical cyclones is the heavy rainfalls of several mm per hour. Nonetheless, warm core storms have been noted in the Mediterranean and are colloquially referred to as “Medicanes”.

For further discussion of tropical cyclones and climate change, see my recent article in Scientific American here.

Kevin E. Trenberth
Head of the Climate Analysis
US National Center for Atmospheric Research

Posted by Olive Heffernan on July 24, 2007
Categories: Atmospheric Science, Climate Science, Hurricanes, In the News, Kevin Trenberth | Permalink | Comments (0) | TrackBacks (0)

Posted by Olive Heffernan on behalf of Kevin Trenberth

Given that human induced climate change is with us, a looming challenge is to predict just what the climate will be. To date, there are no such predictions although the projections given by the Intergovernmental Panel on Climate Change (IPCC) are often treated as such. The distinction is important. A paper presented at the International Forecasting Symposium in New York City in late June 2007 by J. Scott Armstrong and K. C. Green is highly critical of IPCC procedures and "forecasts" for not being based on "evidence based" procedures as outlined in an earlier 2001 book of his. It is true that IPCC does not refer to Armstrong's work as it has dubious relevance.

In fact IPCC does not do forecasts, as explained in my earlier post. The IPCC instead proffers "what if" projections of future climate that correspond to certain emissions scenarios. Armstrong has evidently read only chapter 8 of the IPCC Working Group I report and has therefore overlooked the fact that the other chapters address many of the things he is critical of.

In particular there is clear evidence (“warming is unequivocal”) that climate is changing in ways consistent with the climate forcings. Also, the projections are for all aspects of climate, not just global mean temperature. It has been said that “All models are wrong, but some are useful”. The Armstrong forecast of no change is not useful when the system is already changing in ways consistent with human influences on the composition of the atmosphere. Nonetheless, improvements in forecasting procedures are always welcome.

Bob Carter, a climate change doubter in Australia, has written a distortion of all this in the Courier Mail, issuing various attack against the science of climate change. Andrew Ash has written a rebuttal of these comments.

Another key point is that unlike forecasts based on past experience, weather forecasts are based on numerical weather prediction models and rigorous procedures, not empirical methods, although the latter are used to provide added value (e.g., based on known biases in the model). My own presentation at the same conference provides a description of weather and climate prediction.

Continue reading "Global Warming and Forecasts of Climate Change " »

Posted by Olive Heffernan on July 11, 2007
Categories: Climate Science, Conferences and Meetings, Kevin Trenberth | Permalink | Comments (13) | TrackBacks (0)

Posted by Olive Heffernan on behalf of Quirin Schiermeier

The sun, despite claims to the contrary, is not a factor in recent climate change.

Nature had a news article last week about a paper – and the reactions to it - by Mike Lockwood and Claus Froehlich. Their comprehensive (and conclusive) (re)-analysis of solar trends concludes that the sum of natural changes in solar activity since 1985 would have cooled our climate, were it not for the strong warming effect of increased greenhouse gas concentrations.

The findings, published in Proceedings of the Royal Society A, went online yesterday and have triggered a world-wide echo in the media and in the climate-crazy blogosphere.

That is surprising inasmuch the data are by not what you would call a scientific breakthrough. Indeed, most climate scientists will hardly consider the findings particularly new or surprising. Granted, bringing into line solar observations and measurements (and associated theories) collected during the 20th century is anything but trivial. But no matter how one looks at the issue, existing data were long supposed sufficient to disprove the only seemingly reasonable idea that global warming might be the natural result of increased solar activity.

Lockwood and Froehlich’s study does however go a step further. The two find that the correlation between solar activity and temperature trends post-1985 is actually negative. This means that changes to the sun (including cosmic ray intensity, for that matter) have contributed Less than Zero to the recent sharp rise in average global temperatures.

End of debate? Unfortunately no, I would guess. The inaptly so-named ‘climate sceptics’ who are keen to let mankind off the global warming hook, will not easily abandon this battle-tried warhorse. A natural sun-climate link, albeit invisible and unverifiable, is just the most persuasive among the set of quasi-plausible arguments with which upright eco-optimists attempt to dismiss as a (left-wing? anti-liberal?) conspiracy theory mankind’s responsibility for global warming. The ‘Great Global Warming Swindle’ documentary, to be aired tomorrow in Australia, is just the most-recent example of such attempts to argue that climate change is the effect of the sun.

To further confuse things and the public, solar changes do seem to have had an impact on past climates. Moreover, it is at least not impossible that cosmic ray intensity does influences clouds and climate. There’s nothing wrong with investigating these things - that’s how science goes. But blaming the sun for recent global warming is no science-backed position anymore – it is deliberate disinformation.

Quirin Schiermeier
German Correspondent
Nature

Posted by Olive Heffernan on July 11, 2007
Categories: Climate Science, Climate variability, In the News, Quirin Schiermeier | Permalink | Comments (29) | TrackBacks (0)

Olive Heffernan

In the latest issue of Nature Reports Climate Change, there’s an interesting Commentary by a group of atmospheric scientists who argue that, in assessing the skill of climate models by their ability to reproduce warming over the 20th Century, the latest IPCC Working Group I report may give a false sense of the climate models’ predictive capability.

In ‘Quantifying Climate Change – Too Rosy a Picture?’, Stephen Schwartz of the Brookhaven National Laboratory in Upton, New York; Robert Charlson of the University of Washington, Seattle and Henning Rodhe of Stockholm University, Sweden say that, as it stands, the narrow range of modelled warming misrepresents the certainty with which past temperature changes can be reproduced.

The temperature changes over the 20th Century summarized in the IPCC report represent results from 58 runs with 14 climate models. Although the models fared well at simulating past temperature changes (see Figure 2 for the comparison between simulated and observed warming), Schwarz and co-authors point out the uncertainty range is only half what it would be if uncertainties in the factors driving simulated climate change were accounted for – e.g, cooling by aerosols.

Richard Kerr has an interesting news piece on this Commentary in the July 6 issue of Science entitled ‘Another global warming icon comes under attack’. Kerr’s take on it is that, unlike climate skeptics taking cheap potshots at their choice picks of climate science, the Commentary by Schwarz and co-authors represents a group of mainstream atmospheric scientists challenging an emerging icon of global warming, with climate scientists giving some ground.

Co-author Charlson points out clearly in the Science news piece that “it is not a question of whether the Earth is warming or will continue to warm” under human influence. Rather, Schwarz and co-authors maintain that it is important to give an accurate picture of the range of sensitivities of current models, so that we have a better gauge of what the future might hold.

Kerr reports that IPCC authors say the group has a point, but that their latest WGI report, if read thoroughly, does reflect the uncertainties highlighted in the NRCC Commentary. We will have a response from IPCC authors on the Commentary soon, and will update you when we do....

Posted by Olive Heffernan on July 10, 2007
Categories: Climate Science, In the News, Olive Heffernan, Uncertainty | Permalink | Comments (0) | TrackBacks (0)

Posted by Olive Heffernan on behalf of Kevin E. Trenberth

Aerosols in the atmosphere have been hot topics in several recent climate studies but one wonders if the pollution has made not only the atmosphere murkier but also the scientific reasoning?

In March a widely reported study in PNAS by Zhang et al. linked changes in storm tracks over the North Pacific to Asian pollution. In this case effects on radiative forcing by atmospheric aerosols supposedly increased deep convective clouds over the Pacific Ocean in winter, a finding based on long-term satellite cloud measurements (1984–2005). The blame was assigned to the aerosol effect from Asian pollution, which supposedly leads to intensified storms. Unfortunately the authors did not seem to be aware of the major problems in the satellite-based cloud data that give spurious trends owing to changes in satellites and associated instruments. In particular there were major changes in 1994 in all 3 geostationary satellites (GOES West, GOES East and GMS (Japanese)) observing the Pacific Ocean. All are known to be associated with spurious changes in cloud present in the International Satellite Cloud Climatology Project (ISCCP) data. The ISCCP record is simply not reliable for trends. The time series of the paper are perhaps more a measure of the problems with the data than they are of climate change or evidence of effects of aerosols?

Another recent study by Lau and Kim in the February 27 issue of EOS claims that nature foiled the 2006 hurricane season by increasing aerosols over the tropical North Atlantic in the summer of 2006 (see also Wu 2007 for more general analysis). There is no doubt that sea surface temperatures were lower in 2006 than in the record breaking year of 2005 and that aerosols were more plentiful. It is also clear that there were fewer tropical storms in 2006. But is the former the cause of the latter, as inferred in the article? Or is it more likely that the absence of storms led to less rain and thus less washout of aerosols leading to the increase in atmospheric aerosols? Of course, even in the latter case, there may be a feedback, but estimates of the aerosol effects places them much smaller than effects from changes in cloud and sunshine and from evaporative cooling as winds change.

[Note the contrasting findings between the above two studies with one finding more convection and the other finding less, all due to aerosols!]

Now someone else thinks they can use aerosols to change hurricanes, (as reported by Joshua Zaffos in the Rocky Mountain Chronicle in June 2007). Bill Cotton, a professor from Colorado State University, thinks that dumping dust into a hurricane could be used to weaken the storm. The irony in this case is that Cotton is a skeptic on the issue that humans are changing the climate in spite of overwhelming evidence. Human changes in the greenhouse effect amount to about a 1% change in the energy flow through the climate system. But the energy in a hurricane is enormous; it is typically equivalent in energy to a 1 megatonne nuclear bomb going off every 5 seconds, and Cotton thinks he can mess with a hurricane! What if he is actually right and instead it strengthens the storm?

Posted by Olive Heffernan on June 26, 2007
Categories: Atmospheric Science, Climate Science, Kevin Trenberth | Permalink | Comments (2) | TrackBacks (0)

Posted by Olive Heffernan

While I usually find the FT an excellent source of comment and discussion on climate change, I was somewhat bemused by last week’s Comment from the President of the Czech Republic, Vaclav Klaus, who writes that “global warming hysteria has become a prime example of the truth versus propaganda problem” and urges society to “resist the politicisation of science and oppose the term 'scientific consensus', which is always achieved only by a loud minority, never by a silent majority”.

Though clearly no climate expert, Klaus feels sufficiently component to write on the topic of global warming “as someone who lived under communism for most of his life”. He says “I feel obliged to say that I see the biggest threat to freedom, democracy, the market economy and prosperity now in ambitious environmentalism, not in communism”.

From a man who regards Michael Crichton and Richard Lindzen as voices of reason come denunciations of "Al Gore’s so-called documentary film", "Britain’s – more or less Tony Blair’s – Stern report" and the IPCC’s and G8 Summit’s "ambitions to do something about the weather". (For a direct response to both Crichton’s and Lindzen’s climate denialist arguments, listen to the recent debate with climate scientists Gavin Schmidt and Richard Somerville, among others).

Klaus fails to even attempt to challenge any specifics of the scientific literature on climate change, but instead writes climate science off as ‘propoganda’, making his Comment absurd.

“One exceptionally warm winter is enough…for the environmentalists and their followers to suggest radical measures to do something about the weather”, he writes. Actually, the latest IPCC report on the physical science basis of climate change, which represents the work of thousands of researchers, compiled by hundreds of climate experts, found that “eleven of the last twelve years rank among the 12 warmest years in the instrumental record of global surface temperature”.

He then goes on to claim it is "proven fact that the higher the wealth of society, the higher is the quality of the environment". But with higher per-capita income, the demand for ecosystem services grows. This places more pressure on the environment, often with detrimental effects. For more on this, the Millennium Ecosystem Assessment provides a comprehensive discussion of the relationship between wealth and the environment.

As Felix Salmon points out on the Market Movers blog, much of Klaus’ Comment is rather woolly in meaning, with statements such as ‘small climate changes do not demand far-reaching restrictive measures’ being so general as to be meaningless.

The FT invites readers to challenge Klaus by posting questions to ask@ft.com before this Thursday, June 21, when answers to a select few will appear online from 1pm BST – although the Q&A session is situated in the somewhat misleading category ‘ask the expert’! Personally, I find it disappointing that they are only allowing questions rather than comments, and select ones at that.

Posted by Olive Heffernan on June 19, 2007
Categories: Climate Science, GHG emissions, In the News, Olive Heffernan | Permalink | Comments (6) | TrackBacks (1)

Posted by Olive Heffernan on behalf of Maxwell T. Boykoff

The climate talks at the G8 summit (see Olive Heffernan’s post on the G8 climate talks) have spurred a recent increase in media attention. At the center of this coverage is discussion of cuts in greenhouse gas emissions. Over the past week, proposals ranged from binding emissions cuts across all G8+5 countries by mid-century to ‘aspirational goals’ of cuts, decided on a country-by-country basis through talks over the next two years.

As these rival ‘visions’ of international policy action to combat anthropogenic climate change have been negotiated, the June 7 ‘agreement’ within the G8 put forward a simple plan: 50% emissions cuts by 2050. While this pronouncement has the makings of progress, one of the key yet unresolved facets of the agreements is that of time-scale. While Japan and the EU have pushed for 1990 as the baseline for the metric of 50% emissions, the US has proposed 2007 as the baseline. This tweaking of time scales has a real impact on the actual volume of greenhouse gas emissions that will be removed from the atmosphere, and/or prevented from being emitted.

Continue reading "Climate change and media, science and policy: is time on our side?" »

Posted by Olive Heffernan on June 11, 2007
Categories: Climate Science, Communicating Climate Change, GHG emissions, Maxwell Boykoff | Permalink | Comments (0) | TrackBacks (0)

Further to the post and subsequent discussion on Sunshades, which grew out of this article on geoengineering, I thought I'd point to the new paper by Damon Matthews and Ken Caldeira in PNAS (Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0700419104). It's an interesting paper that has some fascinating insights into the links between climate and the carbon cycle, and I think contains some pretty bad news for would-be geoengineers.

The paper uses a University of Victoria inermediate complexity GCM along with a land cover and carbon cycle model (the Hadley Centre MOSES2 and TRIFFID -- which is pretty much the best acronym in the business) to track climate from 1900 to 2100, using historical data up to the end of the twentieth century and the IPCC A2 carbon-dioxide emissions scenario from then on. Left to itself this gives a temperature increase of 3.5 centigrade over the 200 years. They then compared this baseline to alternative scenarios in which geoengineering strategies were turned on and off at various times. The geoengineering effect -- think of it as a layer of sulphates in the stratosphere, though the model wasn't that specific -- was calibrated to reduce the incoming sunlight in such a way as to counteract the radiative forcing of the carbon dioxide at any given time.

They found that the geoengineering could reduce the change in temperature in the model to something pretty negligible, though with some latitude-dependent effects; in the geoengineered world the poles warm a little compared to 1900 while the tropics cool a little. It also appeared that you could get back to 1900 temperatures even if you started the geoengineering well into the twentyfirst century, as long as you did enough of it.

Various reports of this work have highlighted a fairly obvious subsequent finding: if you stop the geoengineering while having done nothing about carbon emissions you can get some truly horrendously quick warming; your protection vanishes almost instantaneously and the potential warming you have stored up by allowing carbon-dioxide levels to rise suddenly all appears at once. Though it's nice to have some figures on this, it hardly comes as a surprise. Stephen Schneider has been going on about the fact that once you start you can't stop for decades, and in Tom Wigley's Science article (Science 314 pp. 452 - 454 (2006) DOI: 10.1126/science.1131728) last year, which explored the possibility of using a brief period of geoengineering to buy time in which to develop and field the technology needed for radical emissions reduction, there was a nasty looking blip in the warming rate at the point where the geoengineering was turned off. But it's still a sobering thought. While geoengineering through something like sulphate in the stratosphere is "reversible", in that if it starts having nasty effects you can just turn it off and the sulphate will fall out in a few years, that doesn't just leave you with the status quo ante -- it leaves you facing a far faster rate of warming that ypu have ever seen, and the adaptation challenges that go along with that.

There's an extra wrinkle in this paper, too; in the geoengineered world, you get increased carbon-dioxide uptake by the biosphere through the carbon-dioxide fertilisation effect on plants, but no offsetting increase in the carbon dioxide given off by soil respiration, which is taken to be temperature dependent. Turn the geoengineering off and the resultant warming drives up soil respiration in a positive feedback, releasing yet more carbon dioxide and pushing temperatures yet higher. It's a good example of the links between climate and the carbon cycle and the ways they can mess you up. Not as good an example, though, as that offered by the precipitation outlook, which seems to me the most startling result here.

Continue reading "More on geoengineering" »

Posted by Oliver Morton on June 10, 2007
Categories: Biosphere feedbacks, Climate Science, Oliver Morton | Permalink | Comments (1) | TrackBacks (0)

Olive Heffernan

The latest news from the G8 Summit meetings in Heiligendamm, Germany is that leaders of G8 nations have agreed to a ‘compromise deal’ to tackle climate change. According to the BBC, German Chancellor Angela Merkel has said that

'nations have agreed that CO2 emissions must first be stopped and then followed by substantial reductions.’

Although Merkel pushed for a mandatory 50% slash in carbon emissions by mid century, no specific emissions reductions targets have been agreed. Leaders have purportedly said they will negotiate the successor to the Kyoto Protocol within a UN framework. If true, this in itself would be an achievement, as the US recently announced its refusal to participate in global post-2012 negotiations scheduled for the end of the year. Without a consensus on mandatory global emissions reductions, however, today’s compromise deal may be worth little. The need for effective emissions caps is simply the first of numerous contentious issues to be hammered out in determining a global post-Kyoto pact, as reported by Amanda Leigh Haag on Nature Reports: Climate Change, launched today.

Launching in the midst of the G8 climate talks, the site has kicked off with a strong focus on climate policy, emissions reductions, carbon storage and offsetting, as well as covering climate science in research highlights, news and views and in the Journal Club. In our main feature, Amanda takes an in-depth looks at how the Kyoto Protocol has fared thus far – its major triumphs and downfalls. Perhaps the most prominent disappointments have been the failure of some nations to meet what seemed to be modest emissions reduction targets at the outset, and the backtracking of the US on their commitments in 2001. As well as bringing the US back on board, key issues beyond 2012 will include persuading countries such China, India and Brazil to take bold steps to reduce emissions in the next phase, assisting developing nations to adapt to climate change, and avoiding further deforestation, to name but a few.

While some believe that a global extension of the European Trading Scheme is what is needed for mandatory and aggressive reduction of emissions, others are not convinced. In a Commentary, also published today on Nature Reports: Climate Change, Jeffrey D. Sachs, Director of the Earth Institute at Columbia University, argues against ‘an unwieldy global emissions permit system that would be virtually impossible to negotiate and even harder to police’. Yet, despite the considerable global efforts needed to reduce emissions, avoiding dangerous climate change is both practically and economically achievable, says Sachs, if we use a targeted approach aimed at specific sectors.

Continue reading "Shaping the Kyoto successor" »

Posted by Olive Heffernan on June 07, 2007
Categories: Recent contributors, Climate Policy, Climate Science, Conferences and Meetings, GHG emissions, In the News, Olive Heffernan | Permalink | Comments (4) | TrackBacks (0)

Posted by Oliver Morton on behalf of Kevin E. Trenberth

I have often seen references to predictions of future climate by the Intergovernmental Panel on Climate Change (IPCC), presumably through the IPCC assessments (the various chapters in the recently completedWorking Group I Fourth Assessment report ican be accessed through this listing). In fact, since the last report it is also often stated that the science is settled or done and now is the time for action.

In fact there are no predictions by IPCC at all. And there never have been. The IPCC instead proffers “what if” projections of future climate that correspond to certain emissions scenarios. There are a number of assumptions that go into these emissions scenarios. They are intended to cover a range of possible self consistent “story lines” that then provide decision makers with information about which paths might be more desirable. But they do not consider many things like the recovery of the ozone layer, for instance, or observed trends in forcing agents. There is no estimate, even probabilistically, as to the likelihood of any emissions scenario and no best guess.

Even if there were, the projections are based on model results that provide differences of the future climate relative to that today. None of the models used by IPCC are initialized to the observed state and none of the climate states in the models correspond even remotely to the current observed climate. In particular, the state of the oceans, sea ice, and soil moisture has no relationship to the observed state at any recent time in any of the IPCC models. There is neither an El Niño sequence nor any Pacific Decadal Oscillation that replicates the recent past; yet these are critical modes of variability that affect Pacific rim countries and beyond. The Atlantic Multidecadal Oscillation, that may depend on the thermohaline circulation and thus ocean currents in the Atlantic, is not set up to match today’s state, but it is a critical component of the Atlantic hurricanes and it undoubtedly affects forecasts for the next decade from Brazil to Europe. Moreover, the starting climate state in several of the models may depart significantly from the real climate owing to model errors. I postulate that regional climate change is impossible to deal with properly unless the models are initialized.

The current projection method works to the extent it does because it utilizes differences from one time to another and the main model bias and systematic errors are thereby subtracted out. This assumes linearity. It works for global forced variations, but it can not work for many aspects of climate, especially those related to the water cycle. For instance, if the current state is one of drought then it is unlikely to get drier, but unrealistic model states and model biases can easily violate such constraints and project drier conditions. Of course one can initialize a climate model, but a biased model will immediately drift back to the model climate and the predicted trends will then be wrong. Therefore the problem of overcoming this shortcoming, and facing up to initializing climate models means not only obtaining sufficient reliable observations of all aspects of the climate system, but also overcoming model biases. So this is a major challenge.

Continue reading "Predictions of climate" »

Posted by Oliver Morton on June 04, 2007
Categories: Climate Science, Climate variability, Communicating Climate Change, Kevin Trenberth | Permalink | Comments (12) | TrackBacks (0)

Posted by Olive Heffernan on behalf of Gian-Reto Walther

Wasn’t it surprising how the media communicated the findings of the latest IPCC reports? Who would have expected that each of the three reports would produce front-page stories and dominate the public discussion for a considerable while. Whereas for previous issues of IPCC reports, the focus of the reporting media was usually set on the remaining uncertainties of the IPCC statements, this time the (still remaining, though smaller) uncertainties were virtually ignored.

In contrast, a competition among media reports was launched exacerbating the consequences of climate change, one overbidding the other. The logical consequence of this is that sooner or later we end up at a point which cannot be topped. Where to go from there? The answer is what we are just experiencing now. The same media (in part the same journalists) announcing ‘the end of the world’ on the title page (see the article in DER SPIEGEL) a few months later go for the opposite, blaming ‘climate hysteria’ and providing a platform to those who didn’t get their word in the discussion so far. The effect is always the same: The headline is assured, the paid circulation again high, and the public remains confused and can’t really do anything with the progress of scientific knowledge.

The role of scientists is not neutral in this discussion. It is too tempting to provide the media with provocative statements. Only the ‘expert’ with the most spectacular message attracts the attention. For the privilege to appear in public, scientific facts are not clearly separated from expectations, but often intermixed. Minor uncertainties are reported only to avoid describing major ones (BioScience 57(3), 227-236, 2007).

Continue reading "No more to top? Go for the opposite" »

Posted by Olive Heffernan on June 01, 2007
Categories: Climate Policy, Climate Science, Communicating Climate Change | Permalink | Comments (0) | TrackBacks (0)

Posted by Olive Heffernan on behalf of Alex Witze

June 1 is almost here, and for residents of the eastern US, Caribbean and Central America that means just one thing: stock up on the plywood and batten down the hatches, for the Atlantic hurricane season is upon us.

This week’s Nature features a minor rush of hurricane-related items. First off, in a technical manuscript, Ryan Sriver and Matthew Huber of Purdue University spell out how tropical cyclones could play a significant role in mixing the ocean’s topmost layers. They find that about 15 percent of the peak ocean heat transport can be linked to the ocean mixing caused by cyclones. Kerry Emanuel of MIT has had much the same idea before, but the Purdue work extends and better quantifies the role of hurricanes. It’s an interesting study that turns some conventional wisdom on its head: instead of worrying about how climate change affects hurricanes, maybe we should be worrying instead about how hurricanes affect climate change. Quirin Schiermeier, our correspondent in Munich, has a longer news feature on this, plus more on ocean mixing in general. (See also Martin Visbeck’s essay on ocean mixing from last week).

I've got a short news story previewing the 2006 Atlantic hurricane season. The National Hurricane Center in Miami has put out almost exactly the same forecast as last year, calling for an above-average number of storms. The 2006 predictions didn’t pan out so well – blame a late summer El Nino that surged unexpectedly, quashing the number of expected hurricanes. This year, forecasters don’t expect that to happen – and in fact anticipate a weak La Nina, the opposite weather pattern that should permit more hurricanes to form. In other words, buckle up.

One of the interesting things about this year’s season is that there is a new director for the hurricane center. This is a very big and high-profile job in the US; the center director serves as a public face for warning of dangerous storms, including trying to get people to evacuate when necessary. The previous director, Max Mayfield, was well liked by nearly everyone (even if New Orleans officials didn’t listen to his warnings as much as perhaps they should have as Hurricane Katrina approached the city in August 2005). Now the hot seat belongs to Bill Proenza, a former director of the southern region of the National Weather Service. He’s a frequent and outspoken critic of his bosses, and this month has been complaining that his center doesn’t get enough money for forecasting. He may be right, but the Atlantic is by far the best-funded and best-studied of all the world’s hurricane regions. Let us not forget the Pacific or the Indian oceans, which get hammered regularly without the benefit of a highly regarded, highly publicized hurricane center to spread warnings.

The other thing to pay attention to is the relative merits of the different ways of studying wind directons above the sea surface. The US currently has two satellites that measure this factor, but in two very different ways. The QuikSCAT satellite is a scatterometer, bouncing microwaves off the surface and measuring them when they return. The Coriolis satellite uses a radiometer, which measures microwave emissions from the ocean surface itself. Which is the better approach? Each has its merits for detecting wind vectors and each has its disadvantages. Members of Congress, though, are upset that no plans are in the works to replace the QuikSCAT scatterometer, which is far past its intended lifetime. One thing that didn’t make it into the story is the fact that Europe operates its own scatterometer, ASCAT.

If you want to stay up to date as the hurricane season progresses, I recommend checking out the Florida newspapers. The Miami Herald and the St. Petersburg Times are particularly good sources of local information. For more of an overview, check out this week’s New York Times science section , which has a pair of lead stories devoted to hurricanes; John Schwartz, a technology reporter who covered much of the Katrina failure, has a piece on how engineers try to outwit the storms through construction. And Cornelia Dean, who has long covered coastal development issues, has a good overview on the ongoing debates over the potential links between climate change and hurricanes.

Here at Nature, we too will do our part to keep you involved and informed. Complementing our existing coverage online and in print, Nature Reports Climate Change, NPG's dedicated climate change website will be launching next week - check in with us for updated coverage as the season gets underway.

Alex Witze
Senior News and Features Editor
Nature

Posted by Olive Heffernan on May 30, 2007
Categories: Recent contributors, Alex Witze, Climate Science, Hurricanes, In the News | Permalink | Comments (0) | TrackBacks (0)

Posted by Olive Heffernan on behalf of Michael Hopkin

It looks as if the Southern Ocean - the great white hope for sucking up mankind's carbon emissions - is slowly losing its efficiency as a carbon sink due to largely unforseen climate feedbacks. It's early days, but this first real-world measurement of a slowdown in the ocean's ability to dissolve carbon could have worrying implications for those currently thinking about how to stabilize atmospheric greenhouse levels.

Read more on the Southern Ocean's reduced CO2 uptake here

Michael Hopkin
News reporter, Nature

Posted by Olive Heffernan on May 22, 2007
Categories: Recent contributors, Climate Science,