Climate Feedback

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 on behalf of Alex Witze

There are only 17 months left until the US presidential election, which means it’s time for the jockeying to begin in earnest. On climate issues, this means that the leading candidates from both parties have in recent weeks been competing to see who can be greener than thou.

Most notable has been the recent about-face pulled by Illinois senator Barack Obama, the fledgling star of the Democratic party, on coal-to-liquids technology. Illinois is a state with a lot of coal, and so it was perhaps not surprising when earlier this year Obama supported legislation that would give tax breaks to the coal industry to develop coal-to-liquids (CTL) technology. The problem is that CTL is a major emitter of greenhouse gases, even if much of the resulting carbon is captured in sequestration. So recently Obama backed off his support of CTL, saying he thinks it is a good idea only if the technology improves to the point of emitting fewer carbon emissions over its life cycle than conventional fuels. A political move to be sure, but one with significant energy ramifications, given Obama’s prominence in the race so far.

Obama’s leading rival for the Democratic nomination, Hillary Clinton, has no such problems: she represents New York, a state with little interest in coal. She has instead come out with alternative energy plans that rely heavily on taxes and research money to shift the US away from dependence on foreign oil. Using the same rhetoric one hears from many energy experts these days, she says the US needs an investment on the scale of the Apollo moon project to improve energy efficiency. This may be true -- but given the level of wrangling going on in Congress this week over proposed energy legislation, it’s pretty clear that we would have never gotten to the moon at all had politicians been in charge.

Meanwhile, trailing far behind Clinton, Obama, and former senator John Edwards in the Democratic field is a man who really knows his energy: Bill Richardson, currently governor of New Mexico and former US Secretary of Energy. As he points out in a critically-acclaimed YouTube campaign ad, the man is perhaps too qualified to be president. This is the man to listen to for true energy wonkery.

On the Republican side, former New York City mayor Rudolph Giuliani has criticized the Bush administration for a lack of action on climate issues; Giuliani supports a range of approaches, including popular ones like ethanol and unpopular ones like nuclear power. John McCain, the senator from Arizona, is of course a leading proponent of legislation to cut carbon emissions; the bill he co-sponsored years ago with Joe Lieberman, a Democrat-turned-independent from Connecticut, is the early gold standard for climate-change legislation, proposing a 65 percent reduction in carbon emissions by 2050. And the third leading Republican candidate, former Massachusetts governor Mitt Romney, has said relatively little so far, other than the standard lines about reducing America’s dependence on foreign oil.

Potential late entries into the race could also shake up energy and climate issues. Rumors continue to swirl that former vice-president and climate lecturer Al Gore may jump in. And Michael Bloomberg, the billionaire current mayor of New York, this week withdrew from the Republican party in what is widely seen as a move towards a potential presidential candidacy as an independent. He’s been very active on energy issues – for instance, ordering the entire New York taxi fleet to convert to hybrid vehicles within five years. And his closeness with California governor Arnold Schwarzenegger makes for a powerful partnership of regional leaders who want to pave the way for federal action on climate.

Stay tuned – it’ll be a long and interesting 17 months.

Alex Witze
Senior News and Features Editor
Nature

Posted by Olive Heffernan on June 21, 2007
Categories: Alex Witze, Climate Policy, In the News | Permalink | Comments (5) | 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 (5) | 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 (3) | 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)