The world’s pre-eminent climate scientists produced a blunt assessment of the impact of global warming on the US yesterday, warning of droughts that could reduce the American south-west to a wasteland and heatwaves that could make life impossible even in northern cities. In an update on the latest science on climate change, the US Congress was told that melting snow pack could lead to severe drought from California to Oklahoma. In the midwest, diminishing rains and shrinking rivers were lowering water levels in the Great Lakes, even to the extent where it could affect shipping. ‘With severe drought from California to Oklahoma, a broad swath of the south-west is basically robbed of having a sustainable lifestyle,’ said Christopher Field, of the Carnegie Institution for Science. He went on to warn of scorching temperatures in an array of cities. Sacramento in California, for example, could face heatwaves for up to 100 days a year. ‘We are close to a threshold in a very large number of American cities where uncomfortable heatwaves make cities uninhabitable,’ Field told the Senate’s environment and public works committee. The warnings were the first time Congress had been directly confronted with the growing […]