- 08 March 2007
- Exclusive from New Scientist Print Edition. Subscribe and get 4 free issues
- Fred Pearce
British researchers who have seen drafts of last month's report by the Intergovernmental Panel on Climate Change claim it was significantly watered down when governments became involved in writing it.
David Wasdell, an independent analyst of climate change who acted as an accredited reviewer of the report, says the preliminary version produced by scientists in April 2006 contained many references to the potential for climate to change faster than expected because of "positive feedbacks" in the climate system. Most of these references were absent from the final version.
His assertion is based on a line-by-line analysis of the scientists' report and the final version, which was agreed last month at a week-long meeting of representatives of more than 100 governments. Wasdell told New Scientist: "I was astounded at the alterations that were imposed by government agents during the final stage of review. The evidence of collusional suppression of well-established and world-leading scientific material is overwhelming."
He has prepared a critique, "Political Corruption of the IPCC Report?", which claims: "Political and economic interests have influenced the presented scientific material." He publish the document online this week at www.meridian.org.uk/whats.htm.
Wasdell is not a climatologist, but his analysis was supported this week by two leading UK climate scientists and policy analysts. Ocean physicist Peter Wadhams of the University of Cambridge, who made the discovery that Arctic ice has thinned by 40 per cent over the past 25 years and also acted as a referee on the IPCC report, told New Scientist: "The public needs to know that the policy-makers' summary, presented as the united words of the IPCC, has actually been watered down in subtle but vital ways by governmental agents before the public was allowed to see it."
"The public needs to know that the summary has been watered down in subtle but vital ways by governmental agents
Crispin Tickell, a long-standing UK government adviser on climate and a former ambassador to the UN, says: "I think David Wasdell's analysis is very useful, and unique of its kind. Others have made comparable points but not in such analytic detail."
Wasdell's central charge is that "reference to possible acceleration of climate change [was] consistently removed" from the final report. This happened both in its treatment of potential positive feedbacks from global warming in the future and in its discussion of recent observations of collapsing ice sheets and an accelerating rise in sea levels.
For instance, the scientists' draft report warned that natural systems such as rainforests, soils and the oceans would in future be less able to absorb greenhouse gas emissions. It said: "This positive feedback could lead to as much as 1.2 °C of added warming by 2100." The final version does not include this figure. It acknowledges that the feedback could exist but says: "The magnitude of this feedback is uncertain."
Similarly, the draft warned that warming will increase atmospheric levels of water vapour, which acts as a greenhouse gas. "Water vapour increases lead to a strong positive feedback," it said. "New evidence estimates a 40 to 50 per cent amplification of global mean warming." This was absent from the published version, replaced elsewhere with the much milder observation "Water vapour changes represent the largest feedback."
The final edit also removed references to growing fears that global warming is accelerating the discharge of ice from major ice sheets such as the Greenland sheet. This would dramatically speed up rises in sea levels and may already be doing so. The 2006 draft said: "Recent observations show rapid changes in ice sheet flows," and referred to an "accelerating trend" in sea-level rise. Neither detail made the final version, which observed that "ice flow from Greenland and Antarctica... could increase or decrease in future". Wasdell points out recent findings which show that the rate of loss from ice sheets is doubling every six years, making the suggestion of a future decrease "highly unlikely".
Some of the changes were made at the meeting of government invigilators that finalised the report last month in Paris. But others were made earlier, after the draft report was first distributed to governments in mid-2006.
Senior IPCC scientists contacted by New Scientist have not been willing to discuss how any changes took place but they deny any political interference. However, "if it is true, it's disappointing", says Mike Mann, director of the Earth System Science Center at Pennsylvania State University in University Park and a past lead author for the IPCC. "Allowing governmental delegations to ride into town at the last minute and water down conclusions after they were painstakingly arrived at in an objective scientific assessment does not serve society well."
reposted from: New Scientist
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