The NHS in the South East should be ready for a heatwave that could claim more than 6,000 lives, a Department of Health report has warned.
Health Effects of Climate Change in the UK 2008 calculates there is a one in 40 chance of a devastating heatwave in the region by 2012.
"In terms of conventional thinking about risks to health a risk of one in 40 is high," says the report by independent scientific experts.
It predicts summer temperatures could prompt a nine-day heatwave in South East England.
"Without preventive action, this could cause more than 3,000 immediate deaths with more than 6,350 heat-related deaths throughout that summer," the report says.
The report flags up other health risks, including high concentrations of ozone air pollution, which could lead to about 1,500 extra deaths and hospital admissions per year.