The Copenhagen diagnosis: sobering update on the science

Ahead of talks in Copenhagen, a group of leading climate scientists has issued a new report summarising the most recent research findings from around the world and concluding that scientists have underestimated the pace and extent of global warming. The report - titled The Copenhagen Diagnosis - finds that in several key areas observed changes are outstripping the most recent projections by the UN’s Intergovernmental Panel on Climate Change and warns that “there is a very high probability of the warming exceeding 2C unless global emissions peak and start to decline rapidly” within the next decade.

The report points to dramatic declines in Arctic sea ice, recent measurements that show a large net loss of ice from both Greenland and Antarctica, and the relatively rapid rise in global sea levels - 3.4 millimetres per year - as particular reasons for concern. Sea-level rise this century, it states, “is likely to be at least twice as large” as predicted by the most recent IPCC report, issued in 2007, with an upper limit of roughly two metres.

“Sea level is rising much faster and Arctic sea ice cover shrinking more rapidly than we previously expected,” Stefan Rahmstorf, department head at Germany’s Potsdam Institute for Climate Impact Research, said in a press release accompanying the report. “Unfortunately, the data now show us that we have underestimated the climate crisis in the past.”

According to the report, which was released today, there are several elements of the climate system that could reach a “tipping point” in coming decades if current emissions trends continue. The report notes that even at current greenhouse gas concentrations, it is already “very likely” that a “summer ice-free Arctic is inevitable”. The Greenland Ice sheet, too, the report warns, “may be nearing a tipping point where it is committed to shrink”.

The report’s 26 authors include scientists from Germany, France, Switzerland, Austria, Canada, the US, and Australia. Most were also authors of the last IPCC report, and donated their time to draft The Copenhagen Diagnosis. The University of New South Wales’ Climate Change Research Centre provided logistical support.

“We thought that the IPCC report from 2007 was a superb report, but of course science doesn’t stand still,” Richard Somerville, a climate modeler and professor emeritus as the Scripps Institution of Oceanography, said. “And we thought it would be helpful if we could provide some kind of updated assessment.”

In an email message from Antarctica, where he is doing fieldwork, Robert Bindschadler, of NASA, said the group had been prompted to write the report by “the rapidity and serious consequences of climate change”.

Georg Kaser, a glaciologist at the University of Innsbruck, said he hoped policymakers would respond to the report by deciding to “totally phase out fossil-fuel burning within the next two decades”.

“Dreaming is allowed,” he added. “Frankly speaking, I would not like to be a policymaker that has just two options: one, phasing out fossil fuel burning immediately, or two, committing our society to major and long-lasting changes in the climate system.”

The report was already completed but not released by the time world leaders, including President Obama, announced in Singapore on November 15 that they had abandoned the goal of reaching a legally binding agreement in Copenhagen. Since then, several countries have announced commitments to reduce their greenhouse gas emissions, including South Korea, which last week pledged to a cut of 20 per cent below “business as usual” by 2020, and Brazil, which promised reductions of 40 per cent below current projections by 2030. But the United States, with some of the highest per capita emissions in the world and the second-highest overall emissions, after China, has made no commitment, and legislation to curb emissions, which narrowly passed the House this year, is not expected to be taken up by the US Senate until after the Copenhagen session is over.

Andrew Weaver, a climate modeler at Canada’s University of Victoria and one of the authors of The Copenhagen Diagnosis, said he found the announcement that world leaders were abandoning the goal of reaching a binding agreement this year “unacceptable”.

He went on: “Maybe they should be honest, and stand up and say, ‘You know what? As your political leaders we do not accept that we owe anything to future generations.’ I don’t think they’d ever say that, but this is what they are saying if they don’t deal with this problem.”

The Copenhagen Diagnosis is not the first report to warn that climate change is occurring even more rapidly than had been predicted by the IPCC. Indeed, the UN itself has made this point. In September, the United Nations Environment Program released its Climate Change Science Compendium 2009. In the foreword of that report, UN Secretary General Ban Ki-moon noted that “climate change is accelerating at a much faster pace than was previously thought by scientists”. He warned: “Unless we act, we will see catastrophic consequences including rising sea levels, droughts and famine, and the loss of up to a third of the world’s plant and animal species.”

The Copenhagen Diagnosis is explicitly aimed at “policy-makers, stakeholders, the media and the broader public” on the eve of the international climate talks that begin on December 7. It takes up several questions of the sort not typically addressed in scientific forums, but frequently raised on the Internet and in the press. One of these is whether the Earth’s atmosphere is already saturated with carbon dioxide. The answer to this question, the report says, is “Not even remotely. It isn’t even saturated on the runaway greenhouse planet Venus, with its atmosphere made up of 96 per cent CO2 and a surface temperature of 467C.” Similarly, the report states, “global cooling” has not occurred over the past decade, “contrary to claims promoted by lobby groups and picked up in some media”. In fact, “even the highly ‘cherry-picked’ 11-year period starting with the warm 1998 and ending with the cold 2008 still shows a warming trend of 0.11C per decade,” the report concludes.

The report notes that in recent years, solar output has been at a low ebb. Meanwhile, warming has continued: “It is perhaps noteworthy that despite the extremely low brightness of the sun over the past three years temperature records have been broken during this time … The years 2007, 2008 and 2009 had the lowest summer Arctic sea ice cover ever recorded, and in 2008 for the first time in living memory the Northwest Passage and the Northeast Passage were simultaneously ice-free. This feat was repeated in 2009. Every single year of this century (2001-2008) has been among the top ten warmest years since instrumental records began.”

Konrad Steffen, a glaciologist at the University of Colorado who recently returned from taking measurements in Antarctica, said, “We as scientists wanted to make sure we provided all possible information. We tried to stay away from judgment calls - you wouldn’t believe the lengthy emails that we had - but on the other hand we wanted to make sure the urgency is there. We want to tell people it is urgent. We see changes that we did not anticipate two or three years ago.”

Gavin Schmidt, a NASA climate scientist who was not involved in The Copenhagen Diagnosis, said he thought the report was scientifically sound, but questioned whether it would have much impact on its target audience. “Knowing exactly how fast emissions are rising, or sea ice is melting, is useful and interesting, but my guess is that it will not have much effect on the delegates, since it doesn't address the actual equity and political issues that are at the heart of the slow movement towards an agreement,” said Schmidt.

Richard Somerville, of Scripps, acknowledged that scientific information - up-to-the minute or otherwise - was often ignored at climate negotiations.

“I’ve been to several of these meetings,” he said. “The delegates and the leaders say very kind things about the IPCC and thank it for its excellent work. But then, from a scientist’s point of view, once the negotiations start they might as well be negotiating, say, steel tariffs. I’ve actually heard politicians say - I won’t name any names - ‘We don’t want to be constrained by the science’.” But, he added, that only makes it more essential to get the information out.

“Not politicians and not money and not public opinion, but the climate system itself imposes a time scale,” Somerville said. “And if the world chooses not to stick within that, well, Mother Nature bats last.”