In April 2006, National Journal polled members on both sides of the aisle whether they believed global warming is man made and 98 per cent of Democrats said yes versus 23 per cent of Republicans. When the magazine asked the same question last week , only 13 per cent of congressional Republicans answered yes compared with 95 per cent of Democrats.

Meanwhile, the leading international network of climate scientists has concluded for the first time that global warming is “unequivocal” and that human activity is the main driver, “very likely” causing most of the rise in temperatures since 1950.

They said the world was in for centuries of climbing temperatures, rising seas and shifting weather patterns — unavoidable results of the buildup of heat-trapping gases in the atmosphere. But the report of the Intergovernmental Panel on Climate Change also said warming and its harmful consequences could be substantially mitigated by prompt action.

What more does it take?