United Kingdom — A STARTLING report by the United Nations climate watchdog that global warming might wipe out 40% of the Amazon rainforest was based on an unsubstantiated claim by green campaigners who had little scientific expertise.
The Intergovernmental Panel on Climate Change (IPCC) said in its 2007 benchmark report that even a slight change in rainfall could see swathes of the rainforest rapidly replaced by savanna grassland.
The source for its claim was a report from WWF, an environmental pressure group, which was authored by two green activists. They had based their research on a study published in Nature, the science journal, which did not assess rainfall but in fact looked at the impact on the forest of human activity such as logging and burning. This weekend WWF said it was launching an internal inquiry into the study.
This is the third time in as many weeks that serious doubts have been raised over the IPCCs conclusions on climate change. Two weeks ago, after reports in The Sunday Times, it was forced to retract a warning that climate change was likely to melt the Himalayan glaciers by 2035. That warning was also based on claims in a WWF report.
The IPCC has been put on the defensive as well over its claims that climate change may be increasing the severity and frequency of natural disasters such as hurricanes and floods.
This weekend Rajendra Pachauri, chairman of the IPCC, was fighting to keep his job after a barrage of criticism.
Scientists fear the controversies will be used by climate change sceptics to sway public opinion to ignore global warming even though the fundamental science, that greenhouse gases can heat the world, remains strong.
The latest controversy originates in a report called A Global Review of Forest Fires, which WWF published in 2000. It was commissioned from Andrew Rowell, a freelance journalist and green campaigner who has worked for Greenpeace, Friends of the Earth and anti-smoking organisations. The second author was Peter Moore, a campaigner and policy analyst with WWF.
In their report they suggested that up to 40% of Brazilian rainforest was extremely sensitive to small reductions in the amount of rainfall but made clear that this was because drier forests were more likely to catch fire.
The IPCC report picked up this reference but expanded it to cover the whole Amazon. It also suggested that a slight reduction in rainfall would kill many trees directly, not just by contributing to more fires.
It said: Up to 40% of the Amazonian forests could react drastically to even a slight reduction in precipitation; this means that the tropical vegetation, hydrology and climate system in South America could change very rapidly to another steady state. It is more probable that forests will be replaced by ecosystems that have more resistance to multiple stresses caused by temperature increase, droughts and fires, such as tropical savannas.
Simon Lewis, a Royal Society research fellow at Leeds University who specialises in tropical forest ecology, described the section of Rowell and Moores report predicting the potential destruction of large swathes of rainforest as a mess.
The Nature paper is about the interactions of logging damage, fire and periodic droughts, all extremely important in understanding the vulnerability of Amazon forest to drought, but is not related to the vulnerability of these forests to reductions in rainfall, he said.
In my opinion the Rowell and Moore report should not have been cited; it contains no primary research data.
WWF said it prided itself on the accuracy of its reports and was investigating the latest concerns. We have a team of people looking at this internationally, said Keith Allott, its climate change campaigner.
Scientists such as Lewis are demanding that the IPCC ban the use of reports from pressure groups. They fear that environmental campaign groups are bound to cherry-pick the scientific literature that confirms their beliefs and ignore the rest.
It was exactly this process that lay behind the bogus claim that the Himalayan glaciers were likely to melt by 2035 a suggestion that got into another WWF report and was then used by the IPCC.
Georg Kaser, a glaciologist who was a lead author on the last IPCC report, said: Groups like WWF are not scientists and they are not professionally trained to manage data. They may have good intentions but it opens the way to mistakes.