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Nature Vol 447

And so, for another six years at least, it is over. Thousands of authors referring to vast numbers of papers have, in sometimes- contested consultation with the governments that lend their name to the process, provided the world with their best assessment to date of humanity’s prospects and options in the matter of climate change. The Intergovernmental Panel on Climate Change (IPCC) is far from a perfect institution, but it is a necessary and a heartening one. To see the governments of the world almost unanimously acknowledge that they share a problem, and set up a process for identifying its scope that is rooted in the impartial norms of science,. | nature Vol 447 Issue no. 7141 10 May 2007 www.nature.com nature A clear direction The process established by the Intergovernmental Panel on Climate Change has generated a sound foundation of knowledge on which policy-makers must now build. And so for another six years at least it is over. Thousands of authors referring to vast numbers of papers have in sometimes-contested consultation with the governments that lend their name to the process provided the world with their best assessment to date of humanity s prospects and options in the matter of climate change. The Intergovernmental Panel on Climate Change IPCC is far from a perfect institution but it is a necessary and a heartening one. To see the governments of the world almost unanimously acknowledge that they share a problem and set up a process for identifying its scope that is rooted in the impartial norms of science is in itself a reason for hope about the century ahead. The final contribution to the IPCC s fourth assessment report is as we report on page 120 a rather upbeat one. Shifts in the way the world generates and uses energy can the panel says reduce the risks of climate change in exchange for only a fairly small slowing in the rate of growth of GDP. Various ways of bringing about such shifts are discussed. But perhaps because the IPCC is devoted to consensus the relative merits of those schemes are not explored. This is because two economists or for that matter two nations can agree on their analysis of the subject but still differ on what needs to be done. That decision rests in the political sphere. The G8 summit in Heiligendamm Germany next month will offer powerful nations the chance to discuss the merits of opting en masse for the European Unions policy of halving carbon dioxide emissions by 2050. Six months later in Bali Indonesia the countries that have signed up to the United Nations Framework Convention on Climate Change and the Kyoto Protocol will be able to begin the process of thrashing