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N°32 I quarterly I January 2014 Focus | 19 w “Our primary task is to provide information on climate change and objectively review the most recent data concerning various aspects of the phenomenon, some of which are still not fully understood,” explains Rajendra Pachauri, chairman of the Intergovernmental Panel on Climate Change (IPCC). “The Fifth Assessment Report relies on the expertise of 830 scientists from numerous countries and disciplines, working on a volunteer basis.” UNE QUIVOCAL CONCLUSION S The conclusions of the first volume of the AR5 are not surprising. Summarized in a “final draft Summary for Policymakers,” they confirm the trends previously observed by asserting that the “warming of the climate system is unequivocal,” and that “human influence on the climate system is clear.” This claim is supported by atmosphere and ocean warming, declining snow and ice deposits, rising sea levels, and increasing greenhouse gases. Based on several projections using climate and Earth system models, the report looks at the future of climate change. The document states that a substantial and sustained reduction of greenhouse gas emissions is necessary to reverse the trend. Nonetheless, because of the high inertia of the climate system, the 21st century is “likely” or even “very likely” to keep witnessing the changes initiated in the previous century. The summary concludes that “most aspects of climate change will persist for centuries even if CO2 emissions are curbed,” which is unlikely to be the case in the near future. MAKING -OF In preparing their contributions to the report, “the authors have studied the entire body of scientific literature available to determine what is known at a given point in time,” explains French climatologist and IPCC Bureau member Jean Jouzel.1 In this sense, the IPCC does not produce knowledge. Its reports, issued every six or seven years (the fourth was completed in 2007), are themselves organized in three volumes. The first focuses on the science of climate change, the second on its consequences and adaptive solutions, while the third addresses suggestions for reversing the trend. The first volume of the fifth report was published in October 2013. Volumes two and three will follow in March and April 2014, respectively, and a summary document will be issued in October 2014. As emphasized by Jouzel and many other researchers, the IPCC report is only a “snapshot” of current knowledge on climate change. It is not set in stone, nor is it the official viewpoint of the scientific community. “Our position, which reasserts the reality of climate change, could be interpreted as a refusal to discuss the issue,” explains Hervé Le Treut, director 01 Rajendra Pachauri (center) opening an IPC work session in Bangkok (Thailand), April 2007. © S. KHAN/AFP © j. e. ross /corbis © ste ve e./flickr The three volumes of the 2007 IPC report. 01


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