Climate Feedback

Quirin Schiermeier

Rising temperatures cause melting and retreat of large ice sheets, sea ice, and mountain glaciers – that’s pretty much common knowledge by now, as are implications on sea level, ecosystems, water supply and natural hazard risk. But a couple of news stories this week may cause confusion.

That the Greenland ice sheet is losing ice, and that mass loss has further accelerated in recent years, comes as no particular surprise. Using ground observations and satellite gravity measurements, a team led by Michiel van den Broeke from Utrecht University in the Netherlands, estimates that some 1,500 gigatonnes – roughly 1,500 cubic kilometers – have been lost from 2000-2008, equivalent to about 0.46 millimeters of global sea level rise.

Melting rates have accelerated since 2006, with mass loss reaching 273 gigatons of mass per year, equivalent to 0.75 millimeters of sea level rise. Without the moderating effects of increased snowfall, post 1996 mass losses would have been 100% higher, the team writes in a paper in this week’s issue of Science [subscription].

But the cryosphere – those parts of the globe that are permanently or seasonally covered by ice – does have surprises in store. Or so it seems.

Here’s one: Himalayan glaciers (there are tens of thousands of them of) are not – or at least not yet - shrinking as a result of climate change, the world learned this week from an Indian geologist.

“Although shrinking in volume and constantly showing a retreating front, [Himalayan glaciers] have not in any way exhibited, especially in recent years, an abnormal annual retreat,” concludes retired glaciologist Vijay Kumar Raina, formerly of the Geological Survey of India, in a report to India's Ministry of Environment and Forests.

“It is premature to make a statement that glaciers in the Himalayas are retreating abnormally because of global warming,” he goes on.

Following the release of the study – based on observations of 25 glaciers – India’s environment minister Jairam Ramesh was quick to challenge the“conventional wisdom" about melting ice in the world’s tallest mountains.

Fellow Indian Rajendra Pachauri, the chairman of the Intergovernmental Panel on Climate Change (IPCC), was put out: "We have a very clear idea of what is happening. I don't know why the minister is supporting this unsubstantiated research. It is an extremely arrogant statement," he told the Guardian.

The IPCC had warned in its latest report, published in 2007, that Himalayan glaciers "are receding faster than in any other part of the world and, if the present rate continues, the likelihood of them disappearing by the year 2035 and perhaps sooner is very high if the Earth keeps warming at the current rate."

So what's going on? I asked Lonnie Thompson, a veteran glaciologist and leading paleoclimatologist at Ohio State University. Here’s what he said:

“First and foremost this is not a peer reviewed report and nothing scientific can be claimed based on 25 glaciers out of over 15,000 glaciers in the Himalayas and 46,300 in the Himalayas and Tibetan region.”

Continue reading "Greenland ice and Himalayan glaciers: What’s going on?" »

Posted by Olive Heffernan on November 13, 2009
Categories: Climate Science, Cryosphere, In the News, Quirin Schiermeier | Permalink | Comments (1) | TrackBacks (0)

Quirin Schiermeier

The European Union’s environment ministers have reportedly agreed on a negotiation mandate for Sweden for the upcoming climate talks in Copenhagen. Sweden currently holds the EU presidency, which rotates every six months. (German).

The EU has previously said it will reduce its greenhouse gas emissions by at least 20 % by 2020. At a speech to the European Parliament, Andreas Carlgren, the Swedish environment minister, yesterday reiterated that the EU will agree to 30 % cuts only if other parties make sufficient commitments in Copenhagen.

“We see the 30 per cent target as a lever to convince other parties to join us in being more ambitious. By 2050 emissions should have dropped by at least 80 per cent,” he said.

At today’s talks in Luxembourg, environment ministers of the 27 EU member states also called for the Copenhagen climate talks in December to set targets for reductions in greenhouse gas emissions from ships and airplanes. By 2020, global emissions from aviation should be cut by 10 %, and emissions from shipping by 20 %, compared with 2005 levels, the group said according to news reports.

Meanwhile, at a meeting yesterday of EU finance ministers, Poland and other eastern EU member countries blocked a decision on climate adaptation aid for developing countries. The group is concerned that their national contribution to the planned adaptation fund will overburden their economies.

Andreas Borg, the Swedish finance minister, complained about “a lack of commitment by certain member states”.

The EU’s heads of states will now attempt to resolve the issue at a council meeting next week in Brussels, when the EU’s negotiation position for Copenhagen is to be rubber-stamped.

Posted by Olive Heffernan on October 21, 2009
Categories: Climate Policy, In the News, Politics, Quirin Schiermeier, UN Conference on Climate Change, Copenhagen | Permalink | Comments (0) | TrackBacks (0)

Despite decades of research, relationships between clouds, aerosols and precipitation are poorly understood, concludes a review article in Nature today.

Before a cloud can produce rain or snow, rain drops or ice particles must form. Atmospheric aerosols, tiny particles of mineral or organic origin, serve as the nuclei for condensation.

But the precise effects of aerosols on cloud formation and radiative forcing remain controversial. In their review article, Bjorn Stevens and Graham Feingold propose that the uncertainties reflect a failure to take into account processes that act to buffer the response of clouds and precipitation to aerosol changes. Worse, existing tools and methodologies for untangling these processes are inadequate, they say.

"If we wish to make significant strides in understanding the interplay among the aerosol, clouds and precipitation, we consider it imperative to launch significant new international initiatives, with comprehensive, coordinated and enduring measurements, targeting specific regimes and coupled to state-of-the-art modelling," the duo concludes.

Among other things, they say, what's lacking is an array of ground-based remote sensors capable of vertically and temporally resolving the aerosols, clouds, precipitation and the meteorological state.

Quirin Schiermeier

Image: Flickr user laffy4k, Creative Common license

Posted by Anna Barnett on September 30, 2009
Categories: Atmospheric Science, Quirin Schiermeier | Permalink | Comments (1) | TrackBacks (0)

The United Nation’s upcoming climate summit in Copenhagen threatens to get caught in a trap between high expectations and the immense complexity of the task at hand, warns the author of an opinion piece in Nature today [subscription]. Since diplomats cannot possibly produce a useful treaty for the December meeting in the remaining twelve weeks, negotiations should focus on a small number of realistic goals, and leave the rest for later, says David Victor, an expert on international relations at the University of California in San Diego.

A rushed and over-ambitious agreement in Copenhagen, even if it had the superficial appearance of success, could in fact prove a “legal zombie” – neither delivering nor dying – and might be counterproductive for long-term climate protection efforts, argues Victor.

He suggests that negotiators in Copenhagen focus instead on few topics, such as reiterating and extending existing emission targets by developed countries and continuing the Kyoto Protocol’s Clean Development Mechanism, whose expiration would shatter the very credibility of international climate diplomacy. A ‘standby’ agreement, shallow though it might appear, could within two years be developed into a fair and efficient global climate strategy.

The post-Copenhagen process, says Victor, would best be led by the small number of rich nations that account for the bulk of global emissions. Given the endlessly cumbersome UN diplomacy that resulted in the meagre 1997 Kyoto Protocol and that weighs heavily on pre-Copenhagen negotiations, “smaller, more flexible approaches offer the only realistic expectations for making progress in 2010 and beyond,” he says.

Global warming, says Victor, is ultimately a problem of economic cooperation, and must be dealt with using the tools and negotiation strategies that have proved most successful in global trade agreements. In trade issues small forums and even unilateral action have indeed shown to be more efficient than global talks.

But is a last-minute ‘plan B’ for Copenhagen simply a polite paraphrase of the climate summit’s foreseeable failure – and an apology in advance?

No, says Victor. A well-managed disaster in Copenhagen is ultimately more likely to pave the way for effective climate protection than a stapled-together deal.

Quirin Schiermeier

Image: Getty

What do you think? Must climate diplomats change their strategy? Join the discussion here on Climate Feedback.

Posted by Olive Heffernan on September 15, 2009
Categories: Climate Policy, Conferences and Meetings, Opinion, Quirin Schiermeier, UN Conference on Climate Change, Copenhagen | Permalink | Comments (5) | TrackBacks (0)

Twenty years after the Montreal Protocol came into effect to regulate substances that deplete the ozone layer, the annual ozone hole above Antarctica shows no signs of recovery.

A feature article and editorial in Nature today explain why this is so, and why the Montreal Protocol has been a unique success nonetheless.

As things stand, scientists expect the first signs of recovery of springtime ozone depletion in the polar stratosphere around the year 2065. Outside polar regions, where chemical ozone destruction is less pronounced but potentially harmful to human health, it appears as if ozone levels are beginning to increase.

Globally, the recovery of ozone will occur in a changing atmospheric environment. Greenhouse gases have a cooling effect on the stratosphere, and climate change is likely to also alter atmospheric transport and circulation patterns.

What this means for the ozone layer is not exactly clear. It appears that the changes will in some places delay its recovery, while elsewhere they might lead to a ‘super-recovery’ of ozone.

But not only must models of ozone loss and recovery factor in global warming – abnormally low stratospheric ozone has also a marked effect on climate change here and now. Most strikingly, extreme seasonal ozone depletion over Antarctica seems to explain why the Antarctic Peninsula is warming at an alarming rate while the rest of the continent has actually cooled over the last 30 years.

Quirin Schiermeier

Image: View of the South Pole from NASA's TOMS (Total Ozone Mapping Spectrometer) satellite. Credit: NASA

Posted by Anna Barnett on August 12, 2009
Categories: Atmospheric Science, Climate Policy, Quirin Schiermeier | Permalink | Comments (2) | TrackBacks (0)

Northern peatlands, typical for subarctic Scandinavia and Russia, contain one third of the world’s soil organic carbon. How much extra carbon these soils will release to the atmosphere, through accelerated respiration in a warmer climate, has been pretty much guesswork. Data from an eight-year in situ experiment carried out in Sweden now suggest that even modest warming will release enough extra carbon to effectively equalize the European Union’s emissions reductions achieved under the Kyoto Protocol.

Ellen Dorrepaal and her colleagues studied ecosystem response to climate warming at a test site near the Swedish Abisko scientific research station, some 200 kilometres inside the Arctic Circle. In a paper in Nature today (subscription required) they report that warming accelerated the respiration of carbon in peat overlaying the permafrost by almost 70 % - much more than previously thought. Here's an editor's summary.

Extrapolated to the total northern peatland area, the results suggest that climate warming of 1 degree Celsius over the next decade might lead to a global increase in respiration of 38-100 million tonnes of carbon per year. For comparison: The EU’s Kyoto target is to reduce emissions by 92 million tonnes of carbon per year.

The researchers stress that the effect is likely to last: “In contrast to long-term studies in forest, meadow and tundra ecosystems, the warming effect did not decline towards the eighth year of the study,” they write.

The net effect of warming on northern carbon reservoirs includes possible gains from increased plant growth. But in Arctic ecosystems dominated by peat and moss, there are too few productive woody shrubs growing to offset the warming effect on soils.

Quirin Schiermeier

Image: Subarctic peatland in Abisko, North Sweden where the consequences for CO2-respiration rates were investigated. Credit: Ellen Dorrepaal

Posted by Quirin Schiermeier on July 30, 2009
Categories: Categories, Biosphere feedbacks, Climate Science, GHG emissions, Quirin Schiermeier, Topics, Uncertainty | Permalink | Comments (3) | TrackBacks (0)

Some glacial periods in the Earth’s more recent geological past have been cooler and more severe than others, despite very similar greenhouse gas concentrations and orbital parameters. What is it that decouples global temperature from carbon dioxide levels and the solar heat?

Changes in ocean circulation, particularly in the climatically crucial North Atlantic region, are the most likely candidate. A paper in Nature (subscription required) now suggests that some of these changes originate more than 10,000 kilometres away in the subtropical Indian Ocean.

Edouard Bard and Rosalind Rickaby analysed an 800,000-year record of sea surface temperature and ocean productivity from an ocean sediment core retrieved off the southeastern coast of South Africa (Editor's summary). This is the region where a portion of the warm and salty water carried southwards by the Agulhas current, the Indian Ocean equivalent to the Gulf Stream, leaks into the South Atlantic. The inflow compensates for the export of cold Atlantic deep water to other ocean basins. More importantly, it fuels the Atlantic overturning circulation which carries warm tropical surface water towards the poles, and cold deep water back towards the equator.

The strength of this heat conveyor depends on the position of ocean fronts, boundaries between water masses of different temperature and salinity, which are known to intermittently shift northwards and southwards.

Bard and Rickaby suggest that the Agulhas current between Madagascar and the African coast has almost come to a halt during times when the subtropical front in the Indian Ocean migrated northwards by up to 1,000 kilometres. Isotopic data from the sediment record suggest this has happened at least twice, namely during glacial stadials around 340,000 and 420,000 years ago. The closure of the Agulhas ‘valve’ might explain why these glacial periods have been severely colder than most others before and thereafter.

Continue reading "Indian Ocean: Gatekeeper to climate extremes?" »

Posted by Anna Barnett on July 15, 2009
Categories: Ocean science, Palaeoclimate, Quirin Schiermeier | Permalink | Comments (0) | TrackBacks (0)

The G8 meeting last week – the last get-together of the leaders of the world’s major industrialized nations before the United Nations climate summit in December - was loaded with expectations as to what Obama & Co might give climate negotiators to take with them to Copenhagen.

The answer, in a nutshell, is two degrees.

Is that enough? The Nature news story here has the context and offers two opposite expert views.

“The G8 announcement is depressing,” says economist Gwyn Prins, a co-author of the pointed anti-Kyoto polemic ‘How to get climate policy back on course’ (pdf file), whom I interviewed last week for the article.

“Politicians are mistaking making statements for actually doing something. We really need to try something different,” he says. He believes the prospect is “vanishingly small” for developed and developing nations to agree on a meaningful deal in Copenhagen.

Others are not so pessimistic. Hans Joachim Schellnhuber, director of the German PIK and something of an elder statesman of science-led global change diplomacy, is actually quite enthusiastic about the G8’s two degrees target, which he believes will breathe new life into international climate politics.

“Now we can calculate precisely how much greenhouse gas we can still afford to emit if we don’t want to exceed a given probability of getting into dangerous territory,” he says.

Continue reading "What the G8 target means" »

Posted by Quirin Schiermeier on July 15, 2009
Categories: Categories, Climate Policy, GHG emissions, Major Economies Meeting, Politics, Quirin Schiermeier, Topics, UN Conference on Climate Change, Copenhagen | Permalink | Comments (0) | TrackBacks (0)

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)

Cross-posted from The Great Beyond

A gargantuan plan of supplying European consumers with electricity generated in the Saharan desert could see the light of day earlier than even the most optimistic solar energy aficionados had expected.

According to the Süddeutsche Zeitung, a group of 20 large German companies, led by the reinsurance giant Munich Re, and also including Siemens, Deutsche Bank and RWE, is determined to go ahead with an €400 billion project known as Desertec. If fully realized, the envisaged network of huge solar thermal power plants across North Africa could provide up to 15 % of Europe’s overall electricity needs by mid-century.

Next month already, the group plans to create a consortium that is to look in more detail into the technical and financial feasibility of the envisaged project. Developing concrete plans could take two to three years, Torsten Jeworek, a Munich Re board member, told the Süddeutsche Zeitung.

Continue reading "Europe looks to draw power from the Sahara" »

Posted by Quirin Schiermeier on June 17, 2009
Categories: Categories, Business, Energy, 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)

The system of surface and deep currents which make up the Atlantic Ocean circulation, a powerful heat conveyor belt and a poster child for abrupt climate change, is a more complex affair than straightforward textbook diagrams suggest.

Atlantic meridional overturning circulation is driven by cold water that sinks in the seas off Greenland and returns towards the equator at depth. How exactly this machinery works, and where its components sit, is interesting for a variety of reasons – not least in that it helps oceanographers look at the right spots for possible system failures.

That’s why a discovery, reported in Nature today [subscription], is worthy of note. Amy Bower of the Woods Hole Oceanographic Institution in Cape Cod, Massachusetts, and colleagues report that on its way back to the tropics cold Atlantic water takes a different pathway than previously assumed.

Bower and colleagues monitored the trajectories of drifting floats released from 2003 to 2006 into the southward-flowing Deep Western Boundary Current off Canada’s east coast. To their surprise, most floats soon drifted towards the high sea instead of strictly following the boundary current which has been thought to be the main pathway linking the Labrador Sea with the subtropical North Atlantic. Virtual floats ‘released’ in a three-dimensional ocean model at similar positions displayed the same preference for internal ocean pathways as did their material counterparts.

A secret interior ocean path? There you go, modelers!

Quirin Schiermeier

Posted by Olive Heffernan on May 13, 2009
Categories: Journal Club, Ocean science, Quirin Schiermeier | 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 The Great Beyond

Following the collapse on April 4 of a narrow ice bridge that had connected the Wilkins ice shelf with a small island off the Antarctic Peninsula, the northern ice front of the ice sheet is beginning to disintegrate.

A high-resolution radar image taken on April 20 by the German TerraSAR-X satellite shows large icebergs being released from a rift zone near Latady Island. Scientists expect up to 3,400 square kilometretres of the Wilkins Ice Sheet to break into icebergs before a new stable ice front will form.

Quirin Schiermeier

Posted by Quirin Schiermeier on April 29, 2009
Categories: Cryosphere, Quirin Schiermeier, Topics | Permalink | Comments (1) | TrackBacks (0)

China’s forests, shrublands and soils have absorbed a third or so of China’s fossil fuel emissions from 1980 to 2000. Sequestering up to 260 million tonnes of carbon per year, the Chinese land sink is more than twice as large than that of geographic Europe, and comparable in size to that of the United States.

There has been quite some controversy over the total size of the Northern Hemisphere’s terrestrial carbon sink, so this first comprehensive estimate, published in Nature today, is filling a real gap. Given China’s 1.2 billion population and rapidly growing economy, knowledge of how much of its emissions are actually staying in the atmosphere is pretty valuable information. Globally, around 40% of annual emissions stay in the atmosphere; the rest is sequestered by plants, soils and oceans.

The Chinese data come at a time of growing speculation and guesswork over the People's Republic’s future climate and energy policies. Needless to say, the study is of no small relevance with a view to upcoming climate negotiations. The very fact that China’s land carbon sink is large is good news. But the results will also strengthen the Chinese government’s negotiation position at the United Nations climate summit in December in Copenhagen.

Continue reading "EGU: China's carbon sink - it's large" »

Posted by Anna Barnett on April 22, 2009
Categories: Biosphere feedbacks, Climate Policy, Earth science, Mitigation, Politics, Quirin Schiermeier | 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)

In a Mexican eco park, of all places, scientists have found compelling evidence that sea-levels can rise – nah, jump – at scary rates during warm climates such as ours.

That the global sea-level can rise by almost half a metre per decade when huge glaciers melt towards the end of an ice age has already been known. But a paper in Nature today (Editor’s summary) suggests that a similar jump has occurred at the close of the sea-level ‘highstand’ during the warm period, the Eemian Interglacial.

The team, led by Paul Blanchon of the National Autonomous University of Mexico in Cancun, analyzed the age structure of exceptionally well-exposed coral reefs at Xcaret, a popular theme park on the northeast Yucatán peninsula. Because no earthquakes have occurred in the more recent geological history of the region, the peninsula is an ideal location to study sea-level behaviour.

The team found that at the end of the last interglacial many reefs were flooded and replaced by new reefs on higher ground. Age and layering of the corals indicate that a rapid 2-3 metres jump in sea-level occurred around 121,000 years ago, possibly within less than one century.

Only swift and substantial melting of Greenland and Antarctic ice sheets can explain the extreme rate at which the seal level rose to its highstand some 4-6 metres above today’s sea-level.

The implications for our warming planet are clear. As modern temperatures approach those at the height of the Eemian Interglacial, the rate of seal-level rise could soon – perhaps very soon - shift gear, from modest to catastrophic.

The spectacular break-up of the Wilkins Ice shelf off the Antarctic Peninsula is a reminder that we are getting closer to the point where things could get really nasty.

“Given the dramatic disintegration of ice shelves and discovery of rapid ice loss from both the Antarctic and Greenland ice sheets, the potential for sustained rapid ice loss and catastrophic sea-level rise in the near future is confirmed by our discovery of sea-level instability at the close of the last interglacial,” the authors conclude.

Quirin Schiermeier

Posted by Quirin Schiermeier on April 16, 2009
Categories: Ocean science, Palaeoclimate, Quirin Schiermeier, Topics | Permalink | Comments (1) | TrackBacks (0)

The narrow strip of ice which connected the Wilkins ice shelf with a small island off the southwestern Antarctic Peninsula has finally collapsed, threatening to speed up the disintegration of the 11,000 square kilometres-large shelf.

Scientists had expected the break up. A partial collapse of the ice sheet last year had already thinned and twisted the natural ice bridge which connected the Wilkins ice shelf with Charcot Island, providing stability. On 1 April scientists monitoring satellite images of the region first noticed that rifts had occurred in the Manhattan-sized strip of ice. On 4 April it broke into pieces.

Satellite image: Terra SAR-X ScanSAR, 5 April 2009 © DLR, 2009
(Charcot Island is to the left. The island at the bottom right is Latady Island. Behind the broken ice bridge are icebergs from the June/July 2008 break up)

The collapse could accelerate erosion of the Wilkins ice sheet, which is located in one of the most rapidly warming regions of Antarctica. Its demise threatens to speed up the flow of continental glaciers to the coast, with implications for global sea level rise.

Quirin Schiermeier

Posted by Quirin Schiermeier on April 07, 2009
Categories: Cryosphere, Quirin Schiermeier, Topics | Permalink | Comments (2) | TrackBacks (0)

Two papers in Nature today shed light on the possible future behaviour of the West Antarctic ice sheet (WAIS), complete loss of which would produce a worldwide rise in sea level of around 5 metres.

The two teams - one using a high-resolution ice sheet model, the other looking at glacial records contained in seafloor sediment – independently arrive at similar conclusions: The WAIS has intermittently melted during the past five million years or so, and its oscillations follow a 40,000 year cycle in the Earth’s axial tilt. Small variations in tilt – called the obliquity of the ecliptic – result in reduced or increased amounts of sunlight reaching the poles, thus pacing the succession of ice ages and warm periods.

During the warmest interglacial phases the WAIS has in the past episodically collapsed entirely, the studies suggest (Editor's Summary) Global temperatures around 3 degrees Celsius warmer than today seem to have sufficed to initiate the transition from grounded ice to open waters in the Ross Bay, reports the team led by Tim Naish of Victoria University in Wellington, New Zealand, who analysed a sediment core recovered from beneath the Ross ice shelf by the ANDRILL programme. Model simulations suggest the transition from full glacial to intermediate state (such as today’s) to nearly ice-free conditions can proceed rapidly. In the warmest ‘super-interglacials’, such as one around 1.07 million years ago, it took only around thousand years for the WAIS to collapse, report David Pollard and Robert DeConto of Pennsylvania State University in the second study.

Image: Punchstock

Continue reading "Antarctica: Memento melting " »

Posted by Quirin Schiermeier on March 19, 2009
Categories: Cryosphere, Palaeoclimate, Quirin Schiermeier, Topics | Permalink | Comments (1) | TrackBacks (0)

The skies over most land areas are not, as previous studies have suggested, becoming cleaner.
Aerosol pollution has in fact increased most everywhere since 1973, a team reports in Science today (Abstract). Only over Europe have skies brightened, they found.

Kaicun Wang of the University of Maryland, and his colleagues, looked at a 35-year record of clear-sky transparency from 3,250 stations around the world. At many stations visibility had notably decreased - the skies have dimmed.

Air pollution is worst In India, China, Africa and South America, where hundreds of millions are breathing air thick with soot and smog. Clean-air technologies are lacking, or have not yet had much effect, in these regions.

Previous studies concluded that the skies are getting cleaner, and that as a result more sunlight is reaching the surface. Atmospheric scientists believe that aerosols and dust have been shielding us from the worst of global warming.

But the overall cooling effect of aerosols has lately been questioned. The connection between different types of aerosol particles, clouds and solar radiation is more complicated than previously thought. Now it appears as if darker skies don’t necessarily mean less warming, and vice versa. My story
over at Nature News has more about these disturbing uncertainties.

Meanwhile, China is trying hard to reduce air pollution in its most populated cities. Strict regulations aimed at curbing pollution from cars have been set up last year in Beijing and Shanghai.

Quirin Schiermeier

Image: Punchstock

Posted by Quirin Schiermeier on March 13, 2009
Categories: Categories, Atmospheric Science, Quirin Schiermeier, Topics, Uncertainty | Permalink | Comments (0) | 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)

Tropical forests which (still) cover around 10% of the global land area contain more carbon per hectare than any other form of vegetation. It’s obvious from that that their growth or decline has a huge impact on the global carbon budget.

Cutting down forests will add carbon to the atmosphere, no matter which kind of land cover replaces the jungle. But what’s happening in tropical forests that have long been undisturbed by logging, storms or fire? Theoretically, the carbon balance of such old-growth forest – if tree growth and death are in equilibrium, that is - should be next to zero.

But apparently it’s not. In a paper in Nature today (subscription), a team led by Simon Lewis of Leeds University in Britain reports that tree biomass in intact African forests increased between 1968 and 2007. Across 79 plots monitored in ten countries large living trees added an average 0.63 tonnes of carbon per hectare each year. Scaled up to the continent, and including roots, smaller trees and dead wood, African forests seem to have stored 340 million tonnes of carbon per year during recent decades. Previous studies suggested that Amazonian forests are accumulating biomass and carbon at a similar rate. Globally, intact tropical forests seem to take up 1.3 billion tonnes of carbon per year – equivalent to almost 20% of annual carbon dioxide emissions worldwide.

Continue reading "Jungle Fit!" »

Posted by Quirin Schiermeier on February 18, 2009
Categories: Categories, Biosphere feedbacks, Deforestation, GHG emissions, Mitigation, Quirin Schiermeier, Topics | 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)

Stimulating algal growth by adding iron to nutrient-poor ocean regions is one of several geo-engineering methods that could possibly mitigate greenhouse warming. But given widespread worries about possibly harmful side-effects on marine life, large-scale ocean ‘fertilization’ is currently not considered advisable.

Predictably, environmental groups have therefore jumped on an iron fertilization experiment which an international team of oceanographers is set to conduct over the next two months in the Southern Ocean near the island of South Georgia. Critics claim that LOHAFEX violates the moratorium on ocean fertilization activities which the United Nations had agreed upon last year. The Nature news story here has more details.

The somewhat ambivalent wording of the legally binding UN Convention on Biological Diversity adds to the controversy. ‘Small-scale’ scientific experiments in ‘coastal waters’ are exempted from the moratorium, it reads. But ‘small-scale’ is a relative term, and where exactly coastal waters give way to the open ocean remains also undefined.

Picture: The Polarstern (Alfred Wegener Institute)

The team on board the German ‘Polarstern’, who plan to spread 20 tonnes of iron sulphate over less than 20 by 20 kilometres-large patch of ocean surface in the Scotia Sea, hope that the study will provide new insight into how ocean ecosystems respond to fertilization – the very data, hence, that are needed to assess whether or not larger-scale future activities might be justified. But opponents counter that such doing already qualifies as an activity banned by UN law. Pressure groups have launched a signature campaign aimed at stopping the Polarstern crew, which will reach its destination by the end of the week, from dumping its load.

A number of companies, such as the now defunct Planktos Inc., had in the past hoped to commercialize ocean fertilization for the carbon credit market. Scientists and institutes participating in LOHAFEX stress that the experiment has no commercial background whatsoever.

UPDATE:
The Indo-German ocean fertilization experiment, LOHAFEX, has been suspended. The German science ministry, in response to environmental concerns, has asked the Alfred Wegener Institute (AWI) in Bremerhaven that an additional independent assessment be conducted before the planned activities can commence.

Meanwhile, the Polarstern, scheduled to reach the planned study region in the Scotia Sea by the end of the week, will continue its journey as planned. On arrival, the 48 scientists on board will start doing preparatory work, but the team will have to await permission from the ministry before they can dump any nutrients into the ocean. AWI has today commissioned two undisclosed institutions to carry out the required extra assessment. It hopes the reports will be delivered within ten days.

Quirin Schiermeier

Posted by Quirin Schiermeier on January 14, 2009
Categories: Biosphere feedbacks, Business, Carbon markets, In the News, Mitigation, Ocean science, Politics, Quirin Schiermeier, Research, Technology | Permalink | Comments (3) | TrackBacks (0)

After eleven months of legislative work, the European Parliament gave its backing today to the European Union’s (EU) climate change package which aims to ensure that the EU will achieve its self-set climate targets by 2020: a 20% reduction in greenhouse gas emissions relative to 1990 levels, a 20% improvement in energy efficiency, and a 20% share for renewables in the EU energy mix.

EU heads of states, who had hammered out the agreement last week, called the legislation "historic". But critics say the reduction targets are less ambitious than they appear, basically a bluff. What bothers environmentalist most are the many far-reaching concessions to power plants and other emission-intensive industries participating in the EU’s mandatory emissions trading system.

More about this is in my story over on Nature News.

Quirin Schiermeier

Posted by Quirin Schiermeier on December 17, 2008
Categories: Carbon markets, Climate Policy, GHG emissions, Politics, Quirin Schiermeier, Topics | Permalink | Comments (0) | TrackBacks (0)

The year 2008 was likely the coolest year of the current decade, but it was still the tenth warmest year on record since instrumental climate records began in 1850.

The average global sea-surface and land-surface air temperature from December 2007 to November 2008 was 14.3 °C, the World Meteorological Organization (WMO) has announced. This is slightly lower than for all previous years of the ‘naughties’, but still some 0.3 °C above the 1961-1990 annual average. The warmest year on record is 1998, with an average global temperature just above 14.5 °C.

Left: Global map of surface temperature anomalies in degrees Celsius for the 2008 meteorological year. Right: Annual-mean global-mean anomalies, except 2008, which is the 11-month (Jan-Nov) mean anomaly. Credit: NASA Goddard Institute for Space Studies.

When calculating global average temperatures, climatologists prefer the meteorological year, from December through November, as it is easier to split it into actual seasons than is the calendar year.

The WMO temperature analysis is based on land-based weather stations in 188 countries, complemented by measurements from ships, buoys and satellites. NASA’s Goddard Institute for Space Studies and the UK Met Office, which both contributed their own datasets to the WMO analysis, independently arrive at very similar values.

Continue reading "2008 cooling, but the heat is on" »

Posted by Quirin Schiermeier on December 17, 2008
Categories: Climate prediction, Climate variability, Extreme Events, Quirin Schiermeier | Permalink | Comments (3) | 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)

More elderly readers of these pages may remember having heard in their school days back (circa 1970s) that scientists then thought an ice age would be coming soon. I certainly do – even though the alleged ‘global cooling consensus’ in the scientific literature of the time has recently been disproved as a myth.

Now an interesting new paper in Nature [subscription] suggests that a rapid natural transition towards a stable glacial climate, with permanent ice sheets covering large parts of North America and Eurasia, could indeed be ahead.

Thomas Crowley and William Hyde ran a coupled energy-balance/ice-sheet model to test their hypothesis. When forced with long-term variations in daily solar radiation which result from small cyclical changes in the Earth’s orbit, the best-fit model run (that is the one which most accurately reproduced ice sheet variations during the last 3 million years) predicted a rapid transition towards a cold climate regime to occur merely some 10,000 to 100,000 years from now.

Models and theory do indeed suggest that at critical points (namely when climate variability is at a maximum) large ice sheets can rapidly develop from very small perturbations in solar forcing.

Continue reading "Glaciation ahead - on a geological time scale " »

Posted by Olive Heffernan on November 12, 2008
Categories: Climate prediction, Climate variability, Features, Journal Club, Quirin Schiermeier | Permalink | Comments (1) | TrackBacks (0)

In July, a feature in Nature Reports Climate Change
first reported concerns that Nitrogen trifluoride (NF3), a greenhouse gas at least 12,000 times more potent than carbon dioxide, could be substantially more prevalent in the atmosphere than previously estimated.

Now the first actual measurements of the gas, conducted at two clean-air sites in California and Tasmania, confirm that University of California chemist Michael Prather’s initial suspicion was right: The gas, widely used as an etchant in the plasma screen production process, does escape in quite significant amounts to the atmosphere, scientists with the Scripps Institution of Oceanography have found.

Over the last 30 years, the atmospheric concentration of NF3 has increased more than 20-fold, they write in a paper in press at Geophysical Research Letters (subscription). The overall amount of the gas in the atmosphere, currently some 5,400 tonnes, is rising by 11% per year.

In light of these new measurements, the idea that the global warming potential of atmospheric NF3 is negligible must surely be revised. The Nature news story here has more details and explains what experts say should be done about the problem.

Quirin Schiermeier

Image: Punchstock

Posted by Quirin Schiermeier on October 27, 2008
Categories: GHG emissions, Quirin Schiermeier | Permalink | Comments (3) | TrackBacks (0)

Is the global financial crisis good or bad for green issues? The ongoing controversy over the European Union’s ambitious climate and energy package suggests the latter might be the case. But political and economical analysts seem to be increasingly confident that the current crisis might give rise to environmentally healthier policies and investment decisions.

The EU heads of state are still determined to finalise the package before the end of the year, but they expect tough negotiations with a group of reluctant countries led by Poland.

An editorial in this week’s Nature lays out the options and prospects for EU climate policies in light of the financial crisis:

“Striking the required bargains may require more time than the remaining two months under French presidency. But a well-weighed set of rules is far and away preferable to a rushed political compromise that would substantially water down the EU’s ambitious climate plan. (…) Meanwhile, the current economic turbulence cannot be allowed to serve as a pretext for lessening climate protection efforts.”

Meanwhile, United Nations (UN) Secretary-General Ban Ki-moon has said in a statement that the EU plan “could also be a boon for the economy, generating millions of new jobs at a time when the world is suffering from the financial crisis.”

Any agreement will come too late for the international climate talks next month in Poznan, Poland (of all places). But a strong European commitment to cutting greenhouse gas emissions by at least 20 % would be a much-needed signal to the UN climate meeting in Copenhagen 2009, where nations hope to conclude on a successor treaty to the Kyoto Protocol.

Continue reading "From greed to green?" »

Posted by Quirin Schiermeier on October 23, 2008
Categories: Business, Carbon markets, Climate Policy, GHG emissions, Opinion, Politics, Quirin Schiermeier, Topics | Permalink | Comments (1) | TrackBacks (0)

The European Parliament’s environment committee yesterday voted largely in favour of the ambitious European climate action plan (subscription) proposed in January.

The decision, although preliminary, allows the European Union (EU) to go into the upcoming next round of international climate negotiations with a common goal of reducing greenhouse gas emissions across Europe by at least 20 % by 2020. The European commission, Council and Parliament must yet formally agree on details of the plan, but substantial changes are now considered unlikely.

Power plants in Europe will no longer receive free allowances for their greenhouse-gas emissions.TRAVELPIX/GETTY

Most hotly contested were the amendments to the EU’s emission trading system (ETS) which the European commission had proposed in January to strengthen the effectiveness of the scheme.

Introduced in 2005, the ETS is as yet the only mandatory emissions trading system in the world. Until now, power stations and other large European industries have benefitted from generous supply of free permits to release carbon dioxide. Much of the commission’s proposed reform was aimed to end the over-allocation of emission allowances.

The compromise now agreed upon in parliament doesn’t pull the teeth out of the original plan. As of 2013, power stations will not receive free emission allowances anymore. Instead, they will have to obtain 100% of allowances at auction.

Other energy-intensive industries, such as steel and cement facilities which, unlike the power sector, have to compete with suppliers outside the EU, will in a first phase merely have to obtain 15% (rather than 20 % as the commission had initially proposed) of emission allowances at auction. But the allocation of free allowances to manufacturing industries is to be gradually phased out by 2020.

The environment committee did make some concessions to industry, though. The threshold for facilities – currently around 10,000 - which participate in the ETS is to be raised from 10,000 to 25,000 tonnes of annual carbon dioxide emissions.

Continue reading "EU Parliament backs climate plan" »

Posted by Quirin Schiermeier on October 08, 2008
Categories: Business, Carbon markets, Climate Policy, Energy, GHG emissions, In the News, Politics, Quirin Schiermeier, Topics | Permalink | Comments (1) | TrackBacks (0)

If carbon dioxide is trump, then methane is the joker in the greenhouse game. The flammable gas (CH4) is produced in wetlands, landfills and in the guts of cattle and sheep, and it is stored in vast amounts in so-called clathrates, or gas hydrates, in the ocean floor.

The latter stuff has always kindled imagination. In the 1930s, dumbfounded Russian sailors who had lit dynamite for navigational purposes in the Siberian Arctic reported that the air around them started to burn. Had they set on fire methane released from clathrate reservoirs? Perhaps.

Less likely is that methane bubbling up from the ocean floor can makes the water so foamy that ships floating above sink like a rock. File this under Bermuda triangle myths.

But catastrophic methane bursts do seem to be linked with anomalous warming episodes in the Earth’s past, such as the one that occurred at the Palaeocene-Eocene Thermal Maximum around 55 million years ago. Dissociating clathrates may well have been the culprit then.

What had uncorked the bottle is unclear. But in any case, reports this week of methane emissions from sub-sea permafrost beneath the Siberian shelf, and from the seabed off Svalbard, sound alarming.

Geologists assume there are large methane hydrate reservoirs in both regions. Are they beginning to destabilize? Have we lit a time bomb? Is global warning getting out of control?

Media reports this week imply all this, some more and some less cautiously. It’s a wonderful story of course: Weird things happening in the Arctic, strange tales from the bottom of the ocean, Apocalypse Soon! It’s new, it’s exciting, it’s scary - no wonder journalists love it.

But wait a minute. The methane system discovered off Svalbard has probably been active for thousands of years, it’s only that no-one has ever looked for it.

The methane emissions detected in the Laptev Sea are also not a new phenomenon. Russian scientists have observed methane plumes there since the mid-1990s when they began to regularly visit the remote and inaccessible region. It does seem that there are many more, and possibly more vigorous, emission hotspots than was previously thought. But observations are still few; it’s not too much of a surprise that the harder they look the more they will find. I have tried to put the recent discoveries in context in my news story here.

That’s not to say that rising methane emissions, and thawing permafrost, are no concerns. They are, and their sources and causes need to be studied carefully. Long-overlooked methane emissions from living plants, as were just recently confirmed, are proof enough for how poorly methane cycles are actually understood.

But not only in matters climate change there’s a danger of confusing people by media coverage that alternates between alarmism and appeasement. Andrew Revkin of the New York Times has appositely termed the effect a journalistic whiplash for the public.

Science, although intrinsically a never-ending process, will every so often generate journalistic scoops - and sometimes journalistic kitsch. The methane story is exciting, but inflationary use of ‘dramatic’, 'alarming' etc in science stories produces only cheap thrills.

Quirin Schiermeier

Posted by Quirin Schiermeier on September 28, 2008
Categories: Recent contributors, Biosphere feedbacks, GHG emissions, In the News, Ocean science, Palaeoclimate, Quirin Schiermeier | Permalink | Comments (2) | TrackBacks (0)

Hard to believe: The long-standing notion that old forests are carbon neutral – that is, that from a certain age forests cease to absorb and accumulate carbon – has its origin from a mere decade worth of data from one single site.

Although timidly questioned every so often, this apparently wrong postulate has prevailed for more than 30 years, leaving its mark in the Kyoto Protocol which excludes old-growth forests from national carbon budgets.

The finding, reported in this week’s Nature, that old forests do accumulate carbon, and apparently in vast amounts, is therefore anything but marginal. Tropical forests were excluded from the study, because there are too few monitoring sites. But primary forests in the boreal and temporary regions of the Northern Hemisphere alone capture some 1.3 gigatonnes of carbon a year, the meta-analysis of data from 519 plots of forests between 15 and 800 years of age has revealed. An editor's summary of the paper is here.

“Hence, 15 % of the global forest surface, which is currently not being considered for offsetting increasing atmospheric CO2 concentrations, is responsible for at least 10% of the global net ecosystem production,” the authors write.

Obviously, the carbon sequestered in old forest was previously accounted for elsewhere. Disturbingly, given that some offset profiteers praise tree planting as a panacea of sorts for climate change, young forests may actually be sources, rather than sinks, of CO2, if decomposition of soils and older vegetation preceded their creation.

Leaving intact and protecting old forests seems a far better option. This insight comes rather late, but better late than never. Oh, and it will really give climate negotiators something to think about.

My colleague Emma Marris has more in her news story here.

Quirin Schiermeier

Posted by Quirin Schiermeier on September 11, 2008
Categories: Biosphere feedbacks, Deforestation, Mitigation, Personal action, Quirin Schiermeier | Permalink | Comments (2) | TrackBacks (0)

Ozone never ceases to surprise. Scientists report in this issue of Nature that halogen compounds such as bromide and iodine oxide play an unexpectedly large role in chemically breaking down the gas in the troposphere.

Ozone is best known for its presence – or in fact for its seasonal absence - in the upper atmosphere. The stratospheric ozone layer, which protects the earth from harmful ultraviolet radiation, is still being chemically attacked by reactions involving long-lived chlorofluorocarbons (CFCs) banned 20 years ago. But Nature reported last year about a puzzling inconsistency discovered in the established chemical model of stratospheric ozone destruction.

The troposphere is a very different story, though. Near the ground, ozone can affect human health; in high concentrations it is even toxic. Above the ground layer it acts as a greenhouse gas which, when it chemically breaks up, initiates the removal of methane (an even stronger greenhouse gas) and other hydrocarbons from the atmosphere. So ozone loss in the troposphere is a good thing, really.

The gas is typically destroyed in marine regions by chemical reactions involving water vapour. Tropical oceans regions, where levels of solar radiation are high, are thought to be the most important ozone sink.

So what about halogens? Anthropogenically produced CFCs are stable in the troposphere, and are therefore not a reactive halogen source there. But models studies have suggested that bromine and iodine chemistry does contribute to breaking down ozone in the troposphere, potentially changing the global ozone budget by up to 20 %.

The measurements which Katie Read of the University of York and her team have made in the tropical Atlantic Ocean now provide strong confirmation of substantial ‘halogen-mediated’ ozone destruction. An editor's summary and the paper are here.

The team analysed the first eight months of measurements from the new Cape Verde Atmospheric Observatory on the remote island of São Vicente in the tropical Atlantic. They found that average daily ozone loss was around 50 % more than predicted by a state-of-the-art chemistry model that excludes halogen chemistry. Aircraft-borne observations in the area confirmed these findings.

But the team also measured ubiquitous daytime concentrations of iodine and bromine oxides in the layer of the troposphere where most ozone loss occurs. These reactive molecules are emitted by marine algae and liberated from salty sea spray.

In a simple model calculation, the observed halogen concentrations induced just about the extra 50 % ozone loss in the region. The omission of halogen sources in atmospheric models “may lead to significant errors in calculations of global ozone budgets,” the authors write.

What’s special about this study, says Roland von Glasow in an accompanying news and views article here (subscription required), is that the measurements were made in the open ocean where they cannot be influenced by local features that produce halogens.

But even so, the results are significant. Ozone is a powerful oxidizing agent and a key constituent of the troposphere; changes in its concentration will feedback on the lifetime of methane and other hydrocarbons in the air.

It is good to know that tropical ocean regions are a larger-than-thought ozone sink. But the composition of the atmosphere is in such fine balance that its cleansing ability cannot be taken for granted as being permanent. In the face of the new measurements it seems essential to include halogen sources and chemistry in global climate models.

The measurements are likely more representative of the troposphere above the global ocean than previous studies near coastlines. But as Cape Verde is surrounded by biologically highly productive waters one must still be cautious when extrapolating the results, says von Glasow.

Note: RealClimate has an interesting discussion on how the media have spun the story.

Quirin Schiermeier

Picture caption: Model of an ozone molecule. Image created by Ben Mills.

Posted by Quirin Schiermeier on June 26, 2008
Categories: Atmospheric Science, Quirin Schiermeier | Permalink | Comments (0) | 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)

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)

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)

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)

With an uninterrupted 17-million year sediment record of Antarctic’s climatic past now available, scientists are hoping for unique new insights into the continent’s climatic past.

A few initial results of the Antarctic Geological Drilling programme (ANDRILL) were announced last week at the general assembly of the European Geosciences Union in Vienna. There is an online news story here.

Antarctica’s ice sheets, so it seems, respond more sensitively to climate fluctuations than has been assumed. During warmer periods, the West Antarctic Ice Sheet and its floating extension, the western Ross Ice Shelf, have shrunk substantially. Some 3.5 million years ago the ice seems to have disappeared completely for around 200,000 years. There were snow-capped mountains, alpine trees, gushing rivers, quiet lakes – the frozen continent was a place where you would love to go fishing or hiking, were it not for the midges.

The world was warmer then than it is today, but not substantially so. If temperatures continue to rise, glaciers in Antarctic’s warmer western part might begin to retreat again before long. A few million years ago, Antarctic melting probably raised sea levels globally by 10 metres or so. If history repeats itself, we’re headed for trouble.

Quirin Schiermeier

Posted by Quirin Schiermeier on April 24, 2008
Categories: Recent contributors, Categories, Conferences and Meetings, EGU 2008, Palaeoclimate, Quirin Schiermeier | Permalink | Comments (5) | 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)

It’s been quite a while since the Gulf Stream was last on the Nature cover. This week the old highlight is back.

Now that’s a topic which has caused an awful lot of confusion before. “How global warming will cause the next ice age”, stuff like that. So just to be clear: the Gulf Stream is the mostly wind-driven upper limb of the Atlantic meridional overturning circulation, which ceaselessly transports warm surface water from the Caribbean to middle and high latitudes on the other side of the Atlantic. Yes, ceaselessly. As long as the Earth keeps rotating there’s really nothing in the world (not even global warming) that could bring it to a halt.

It is common knowledge - and true - that the British Isles and Scandinavia enjoy a much warmer climate than Newfoundland or Labrador thanks to the Gulf Stream. But its climatic influence goes far beyond that, a US-Japanese team report in a paper in Nature this week.

They detected the Gulf Stream’s signature in the entire lower atmosphere - namely in air and cloud temperatures, rain bands, pressure fields and wind convergence - above its meandering cross-Atlantic course, and far inland in Europe.

That the influence of the Gulf Stream might penetrate deeply into the atmosphere has been previously assumed. Firm evidence that this is indeed the case, and vehemently so, comes from the combination of satellite observations, operational weather analysis and atmospheric circulation models which the team utilised for their study.

Very likely the Gulf Stream’s direct local effects on the atmosphere are tele-connected, via planetary atmospheric waves, with weather conditions in far-away regions. How frequent and pronounced these remote responses might be is not at all clear. But it seems at least as if Gulf Stream-driven atmospheric dynamics over the North Atlantic have a marked influence on hemisphere-wide climatology.

This, you’ve guessed it, adds another piece to the climate change puzzle. Come what may, the Gulf Stream will not ‘run dry’. But its strength does vary, and a possible weakening of the Atlantic overturning circulation, to which it belongs, is unlikely to leave the Gulf Stream unaffected.

A new ice age will not come over Europe because of that, but storm tracks and rainfall patterns could be affected in rather unpredictable ways.

Quirin Schiermeier

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

Posted by Olive Heffernan on March 12, 2008
Categories: Extreme Events, Features, Journal Club, Ocean science, Quirin Schiermeier | Permalink | Comments (5) | TrackBacks (0)

Posted by Oliver Morton on behalf of Quirin Schiermeier

A meeting this week in Potsdam, Germany – "Global Sustainability – A Nobel Cause" – ended with the formulation of a memorandum calling for a global contract between science and society and a multi-national innovation programme on the scale of the Apollo programme to meet the challenges arising from climate change.

Earlier at the meeting, the likes of Rajendra Pachauri, Nicholas Stern, Carlo Rubbia and Murray Gell-Mann had reminded the 100 or so participants – among them a dozen Nobel Laureates – about the current state of the science and ecnomics of climate change, and suggested some possible solutions such as solar energy. Convener John Schellnhuber, the scientific director of the nearby Potsdam Institute of Climate Impact Research, who advises the German government on climate issues, brought together an impressive programme. Most talks were interesting, some were brilliant. The German Chancellor Angela Merkel delivered a vivid and informed speech, seemingly without using any notes, which focussed on the issues of equity and carbon ‘justice’. .

What the meeting made clear (again) is that the world has a habit – a carbon habit. And just like some alcoholics, the patient has intellectually grasped his state. It seems to understand pretty well what’s going wrong with it and why, and is capable of lecturing eloquently about the causes and symptoms of its problem (although David Gross, 2004 Nobel Prize winner for physics, sceptically remarked that climate sciences could benefit from a good dose of theoretical physics). What it lacks, however, is the firm will and the capacity, an emotional capacity perhaps, needed to lastingly change its behaviour and stop the abuse.

Continue reading "Potsdam symposium" »

Posted by Oliver Morton on October 12, 2007
Categories: Quirin Schiermeier | Permalink | Comments (1) | 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)