Synthesizing reams of data from its three previous reports, the United Nations Intergovernmental Panel on Climate Change for the first time specifically points out important risks if governments fail to respond: melting ice sheets that could lead to a rapid rise in sea levels and the extinction of large numbers of species brought about by even moderate amounts of warming, on the order of 1 to 3 degrees.
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Even though the synthesis report is more alarming than its predecessors, some researchers believe that it still understates the trajectory of global warming and its impact. The I.P.C.C.’s scientific process, which takes five years of study and writing from start to finish, cannot take into account the very latest data on climate change or economic trends, which show larger than predicted development and energy use in China.
Of course, this time the problem isn't interstellar aliens. Rather, we are confronting the Pogo Theorem: "We have met the enemy, and he is us."