Stormy weather for the IPCC: over the last few months, the International Panel on Climate Change has been the target for virulent attacks on the Internet, which claim that "global warming is nothing more than left-wing fantasy," or a process of "mystification to launch green capitalism" etc. And the cause of this onslaught? A handful of researchers (from Britain's renowned Hadley Centre for Climate Prediction and the University of East Anglia, and Germany's Kiel University) who have recently questioned the message on global warming that the IPCC has been hammering home over the last 20 years.

The IPCC asserts that the phenomenon of global warming results from an accumulation of greenhouse gases (GHG), which has largely been caused by human activity. But according to the recent findings of some British and German laboratories, global temperatures were virtually unchanged between 1998 and 2008, and they may well diminish over the next one or two decades. The resulting controversy has sounded a bum note that could disrupt the carefully orchestrated run-up to next month's UN conference in Copenhagen, which will attempt to establish a political agreement on global measures to counter climate change.

Obsessed with reducing CO2 emissions

Founded in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Program (UNEP) following a request from the G7, the IPCC has produced four reports that have had a major impact on public opinion. "Our job has been to sound the alarm," explains Jean Jouzel, joint chairman of one of the working groups that make up the vast network of experts, which includes climatologists, ecologists, biologists, geographers, sociologists and economists. In the space of a decade, the IPCC has won over the world's major political leaders, who are now ready to fund major programs to change lifestyles and consumer habits in the hope of reducing CO2 emissions. It has also convinced most of the world's press, which enthusiastically publicizes each of its long awaited assessment reports.

Its first report, in 1990, confirmed the scientific data that had initially prompted concerns over climate change and led to the creation of the UN Framework Convention on Climate Change at the Rio summit of 1992. Five years later, its second report provided the basis for the 1997 adoption of the Kyoto Protocol, which was the first ever international treaty to combat global warming. In 2001, its third report presented the first ever summary for policymakers. Finally, its most recent report in 2007, led to heated debates at the Bali climate conference, and engendered a growing consensus on the need for an even greater reduction in C02 emission levels in the industrialized world—a cut of not just 25% but 40%—by 2020, if humanity is to prevent a global temperature increase of more than 2°C over the next 90 years. This fourth report was also instrumental in raising the spectre of the effects of extreme climate change: hurricanes, torrential rains, catastrophic drought etc.

Scientists sidelined

The IPCC owes much of its remarkable efficiency to its unique organizational structure. "Every IPCC report presents an inventory of the latest high-level research on climate," explains Jean Jouzel. Each of the multi-volume reports is a kind of a huge synthesis where every word in the text has been negotiated. "The result is a massive document of about 3,000 pages, which is reviewed and annotated by the scientific community before being submitted to the representatives of governments" adds Stéphane Hallegatte, a researcher at Météo France and a member of the IPCC. An initial series of summaries is extracted from this document, and then a second more condensed series is prepared for policymakers. "At that point, the report enters the phase of approval by government representatives, and any modifications have to comply with all of its findings—a procedural safeguard that ensures that the summary will be a faithful reflection of the data in report," says Jean Jouzel. The pages of the fourth report "were drafted and signed by 800 scientists, before being reviewed by 2,000 expert readers," explains Stéphane Hallegatte.

In view the scale of this mobilization, it is not surprising that the cause of climate change is now associated with a number of martyrs, who are present on both sides of the debate. A leading figure in the sceptics camp, MIT professor Richard Lindzen publically withdrew from the IPCC, claiming that his objections based on climate feedback mechanisms had not been taken into account. In an article published in the Wall Street Journal three years ago, he complained that other scientists who had cast doubts on the theory of global warming—Henk Tennekes (Netherlands), Aksel Winn-Nielsen (WMO), Alfonso Sutera and Antonio Speranza (Italy)— had similarly been sidelined. Among the proponents of climate change, James Hansen, a researcher at the Goddard Institute for Space Studies (NASA), was placed under censorship by the Bush administration, which was none too pleased by his calls for urgent emissions reductions to reduce global warming. One ongoing source of doubt is the role of former British Prime Minister Margaret Thatcher, who from the outset was accused of exploiting concerns over climate change in a bid to promote her campaign to reduce Western dependency on Middle Eastern oil. There is always the risk that the cause may become tainted by some other agenda, but as Stéphane Hallegatte insists, this is no reason "to pretend that the world is being manipulated by a cabal of scientists."