IT鈥橲 enough to make you think there is an election looming. After four years of reticence, the Bush administration has finally accepted what thousands of scientists and politicians claim to have known all along 鈥� that human activity has caused the increase in global temperatures seen over the past 30 years.
A report issued on 25 August that summarises climate-change research by 13 US government agencies, and is endorsed by the secretary of commerce, secretary of energy and the president鈥檚 science adviser, says 鈥済lobal warming in the first half of the 20th century 鈥� estimated at 0.4 掳F [0.22 掳C] above pre-industrial temperatures 鈥� was likely due to natural climate variation鈥�, including increased solar activity. But the roughly 0.5 掳C rise over the second half of the century, and most dramatically in the last 30 years, could be explained only by taking 鈥渁nthropogenic forcings鈥� of carbon dioxide and other greenhouse gases into account.
鈥淲ell over 98 per cent of scientists that are competent in this area would agree with that,鈥� says Thomas Graedel, an industrial ecologist at Yale University who has reviewed the government鈥檚 climate-change research strategy.
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鈥淭he big question is what effect this will have on climate policy,鈥� says Anthony Janetos, director of the global-change programme at the Heinz Center, a non-profit environmental policy think tank that has ties to Teresa Heinz Kerry, wife of presidential candidate John Kerry. 鈥淭he administration has been pretty consistent saying they believe in voluntary actions [to cut greenhouse gas emissions]. I haven鈥檛 seen any indication they have changed their mind, but if they had, that would be big news indeed.鈥�