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March 2009 Archives

The cultural differences between scientists and politicians were clear at the closing session of the Copenhagen Climate Congress.  Five scientists presented their take on the key findings from the conference to Danish prime minister Anders Fogh Rasmussen, who will host the COP delegates at the negotiations in the same Copenhagen conference centre in December.


Stefan Rahmstorf of Germany's Potsdam Institute stressed how he sees the 2 degree target for climate change as an absolute upper limit, not just a guideline. "When politicians talk about an ambition of 2 degrees, if all goes reasonably well we get 3," he said. "As scientists that really is an upper limit we should not cross. At 2 degrees I think we have more than a 1 in 6 chance of really bad impacts." This morning delegates heard John Schellnhuber, director of the Potsdam Institute, explain how that more than 1 in 6 chance is worse than your odds of survival when playing Russian Roulette.


Rasmussen, however, was somewhat dismayed by this news. "I need some concrete advice now," he said. "We had a very hard battle in the EU to get the 2 degree target, and now you tell me it's not enough. I need to know and I need to know today."


Will Steffen of Australian National University stepped in to the debate to explain that coming up with a number is a risk game. He believes it's up to politicians to decide how much of a risk society is prepared to take. And while Steffen thinks 2 degrees is a reasonable target for 2009, the situation could change in five years. Rahmstorf insisted he would advise a more ambitious target if at all possible, one that leaves room for manoeuvre and a safety margin.


In response, Rasmussen recommended that scientists not give politicians too many moving targets. "It is already complex," he said. "I need your help to move this in the right direction." The process now is for discussion of the agreement at the G8 summit in July, the UN meeting in September and the December meeting back in Copenhagen. Rasmussen says there will be three key elements to the agreement - targets, funding and verification.


With regards to targets, the aim is to cut global emissions by 50% compared to 1990 levels by 2050. "I have noted that that should be a minimum," said Rasmussen. A binding agreement should come from developed countries to cut their emissions substantially by 2020, and by 80% by 2050. Developing countries, meanwhile, should cut their emissions by 15-30% compared to business-as-usual by 2020, and after that create real reductions.


Developed countries should provide funds to developing countries to help them transform to a low carbon economy, with forests and land use as part of the package, continued the prime minister. They should also help with adaptation and the dissemination of technology. And a reliable and transparent system is needed to verify international actions, both on emissions and technology.


"I call on the scientific community to follow the trends closely and help us adjust our course," said Rasmussen.



Climate Change Congress: Stern words

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"I realise most of you here are scientists and not economists and that is your fault," were the first words of Nicholas Stern of the London School of Economics at his plenary talk at the Copenhagen Climate Congress.


Later he laid out the pros and cons of both carbon trading and carbon tax schemes. "Don't let anyone kid you that a tax scheme is clearly the best," he said.


Stern put together the Stern Review of the economics of climate change in 2006 for the UK government. In the light of evidence since then, he believes his report underestimated the damages climate change could cause and the speed of that change. Today he says two big challenges face us  - poverty and climate change. And if we don't fix climate change we will create a physical climate so hostile that the hard-won gains in development are lost.


"We should be supporting development that is shaped and driven by developing countries themselves," said Stern. "This is about working together to expand the options that people have, the technologies that are available...then there would be a real partnership."


The necessary resources could come from carbon finance, overseas development assistance, private investment, and the various kinds of guarantee and insurance instruments available to the international finance institutions.


Stern stressed that if developed countries can show examples where they have achieved low-carbon growth, it would be far more powerful than just talking about it. To date developing countries have only seen development in the west result from a high-carbon growth path but this need no longer be the case.


Stern reckons that a high-carbon growth future would kill itself, firstly from high hydrocarbon costs and then because of climate change. "We should see action as, rather, attraction and inaction as inexcusable," he said.


That action is particularly attractive in an economic slowdown, when resources are cheaper. "Now's the time to get the unemployed of Europe getting our houses more energy efficient," said Stern. "We must not sow the seeds of the next bubble. We can come out of this one and lay the foundations for low carbon growth."


Are you an expert in the carbon emissions of the transport industries? If so the University of Cambridge, UK, would like to hear from you. Terry Barker of the Cambridge Centre for Climate Change Mitigation Research (4CMR) is looking to put together two proposals for schemes to decarbonise the aviation and shipping industries in time for the climate change negotiations in December.


Speaking at a lunchtime workshop at the Climate Change Congress in Copenhagen, Barker explained how he's keen to bring as many different modelling approaches to bear on the problem as possible. And he's looking to bring together representatives from each of the industries to work together with the relevant scientists, as well as representatives from government and NGOs.


"The more independent modelling teams the better," said Barker, who is also looking for short-term funding for the project. "The results are more convincing if we're coming at them from different approaches."


If you're interested in participating, send an email to

Tropical rainforest currently removes about one petagramme of carbon from the atmosphere each year, a figure equivalent to around one-tenth of 2007 emissions. And most global climate models project that the rainforest's net storage of carbon will continue or even increase as a result of carbon dioxide fertilization.


But David Hilbert of CSIRO, Australia, has found that the Australian rainforest has showed a consistent trend of lower tree mass in warmer climates. Hilbert and colleagues studied 17 sites in north-east Australia for up to 35 years. There was no trend over time, but both the growth rate and the mortality rate increased with temperature. (Recruitment rate - the growth of new trees - was independent of temperature but increased with increasing mortality). As the mortality rate increased, the basal area - the cross-sectional area at a height of 1.3 m of all trees larger than 10 cm in diameter, and an indicator of the amount of carbon stored - decreased.


Hilbert says that the ecosystem feedbacks in global climate models are based on short term processes such as carbon fixation by photosynthesis or decomposition, whereas in the longer term stocks of carbon are controlled by tree demographic processes. "Despite higher tree growth rates and higher turnover of biomass, rainforests in warmer climates stores less carbon because of the higher mortality rate," he added.


The team estimates that tropical rainforests will lose 14 Mg of carbon stored per hectare per degree of climate warming. So that means a total loss of storage in the world's rainforests of 24.5 Pg of carbon per degree of warming - equivalent to 2.5 times 2007's carbon emissions. If warming proceeds at 0.05 degrees per year (the maximum IPCC prediction), that would give a storage loss of 1.2 Pg of carbon per year. Scarily, that's greater than the amount we assume that the rainforests remove from the atmosphere each year today.

Once an ice sheet starts to melt, the surface of the ice gradually decreases in altitude and becomes warmer, leading to yet more melting in a positive feedback effect. According to Jonathan Bamber of the University of Bristol, UK, speaking at the Copenhagen session on tipping points, that makes the process pretty much irreversible once it's started in earnest - you'd need a very substantial cooling for the ice sheet to return.


The complete collapse of the Greenland ice sheet would lead to around 6.5 m of sea level rise. So scientists are keen to know at what temperature melting of the ice sheet is likely to become irreversible. A few years ago Jonathan Gregory calculated this threshold at 3 degrees of temperature rise but Bamber says there are two lines of evidence that suggest this is wrong - the past and the modelling future. "I think there are other processes in there that may be important," he said. In the Eemian Greenland was about 5 degrees warmer than today, considerably above Gregory's threshold, but there was still an ice sheet present (although probably about half its present volume) and it remained in place for 20,000 years.


Bamber has recalculated the critical threshold temperature for ice sheet melting by forcing two surface mass balance models with real future climate. The first model, a positive degree day (PDD) model, which says that the ice sheet will melt if the temperature falls below zero, gave a temperature threshold of 4 degrees. That figure is comparable to Gregory's threshold of a 3 degree average global temperature rise, which corresponds to a temperature increase in Greenland of around 4.5 degrees.


But in Bamber's second calculation the relatively sophisticated energy balance model, which he believes better represents ice sheet behaviour, gave a threshold of 8 degrees for irreversible melting of Greenland - double the previously published threshold.


Climate Change Congress: Raj Pachauri heads to Yale


Raj Pachauri, chairman of the IPCC, is to take up a half-time position as director of a new climate and energy institute at Yale University, US, starting in the autumn. The announcement came at the Copenhagen Climate Congress.



Climate Change Congress: Is it all a British plot?

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Delegates arriving this morning were handed leaflets headed "British climate lies will lead to genocide". According to Denmark's Schiller Institute, the Copenhagen climate change congress has been wrongly promoted as an international scientific conference and is instead part of "the latest aggressive assault by the British Empire against the just yearnings of the nation states and peoples of the world for economic development".


Speakers questioned after the first press briefing of the day gave these views pretty short shrift, however.


"Unabated climate change will make it much harder to eradicate poverty and beyond a certain threshold will make it impossible," said John Ashton of the UK Foreign and Commonwealth office.


Ian Chubb of Australian National University added, "As an Australian I think we are very good at looking for British plots and even we can't see one here."

Climate Change Congress: from art to gloom


The Danish passion for design came to the fore at the Climate Change Congress opening session this morning. Not only was there an unusually artistic backdrop at the front of the hall - a massive cut-out version of the conference iceberg logo - but around 2500 delegates, including Danish royalty, were also entertained with some virtuoso recorder playing.


Once the conference kicked off for real, however, the outlook was more bleak. A wide range of climate and other scientists have come together to discuss their discoveries since the IPCC report of 2007. Because of the way that report was produced, that means any results from the last 4-5 years. In a nutshell, the news is not good.


Carbon emissions are now at the upper bound of those projected by the IPCC, sea level rise could well top one metre by the end of the century, and it appears that tropical forest carbon sinks are likely to decline as the planet warms, to name just a few.


"The good news is in the social sciences and the human sciences," said Katherine Richardson of the University of Copenhagen and chair of the conference scientific steering committee. "In those fields you will find we have a lot of tools in our toolbox, things we can do already."


For once, the credit crunch is arguably good news as it's likely to see a slowdown in world carbon emissions. Although, according to Terry Barker of the University of Cambridge, it could also lead to a collapse of the European emissions trading scheme as declining demand for electricity leads to a plummeting price for emissions credits.


"Politicians have refocused on jobs because of the economic crisis," said John Ashton of the UK Foreign and Commonwealth Office. "If we want a successful response to climate change we have to reframe it in terms of jobs. We need to build the prospect of a low carbon recovery."


The plan is for the output from the conference to feed into the climate negotiations for the follow-on treaty to the Kyoto Protocol to be held in the same venue in December. "We are looking for things to happen from this conference, not just more talk," said Ian Chubb of Australian National University


With that in mind, organizers will produce a 30 page long synthesis report by June 1st while next year will see the release of a book. What's more, at the conference closing ceremony on Thursday, Danish prime minister Anders Fogh Rasmussen will receive a summary of a handful of key results presented at the event. He'll then discuss these with a panel of leading researchers, including Dan Kammen of the University of California, Berkeley, and Nicholas Stern of the London School of Economics and Political Science. Watch this space for more.

Coming soon: Climate Change Congress

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All the news and analysis from the International Scientific Congress on Climate Change in Copenhagen, Denmark.