IT IS a case of the dog that didn鈥檛 bark. The dog in this instance was the Intergovernmental Panel on Climate Change.
For several years, climate scientists have grown increasingly anxious about 鈥減ositive feedbacks鈥� that could accelerate climate change, such as methane bubbling up as permafrost melts. That concern found focus at an international conference organised by the British government two years ago, and many people expected it to emerge strongly in the latest IPCC report, whose summary for policy-makers was published in Paris last month.
It didn鈥檛 happen. The IPCC summary was notably guarded. We put that down to scientific caution and the desire to convey as much certainty as possible (New 杏吧原创, 9 February, p 3), but this week we hear that an earlier version of the summary contained a number of explicit references to positive feedbacks and the dangers of accelerating climate change. A critique of the report now argues that the references were removed in a systematic fashion (see 鈥淐limate report 鈥榳as watered down'鈥�).
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This is worrying. The version containing the warnings was the last for which scientists alone were responsible. After that it went out to review by governments. The IPCC is a governmental body as well as a scientific one. Both sides have to sign off on the report.
The scientists involved adamantly deny that there was undue pressure, or that the scientific integrity of their report was compromised. We do know there were political agendas, and that the scientists had to fight them. As one of the report鈥檚 33 authors put it: 鈥淎 lot of us devoted a lot of time to ensuring that the changes requested by national delegates did not affect the scientific content.鈥� Yet small changes in language which individually may not amount to much can, cumulatively, change the tone and message of a report. Deliberately or not, this is what seems to have happened.
Senior IPCC scientists are not willing to discuss the changes, beyond denying that there was political interference. They regard the drafting process as private. This is an understandable reservation, but the case raises serious doubts about the IPCC process. A little more transparency would go a long way to removing those qualms.
