The first deaths from infectious disease attributed to global warming have occurred in Britain, official figures suggest.
Cases of legionnaires' disease, the bacterial lung infection which kills more than one in ten of those it infects, reached record levels in August and September and experts say the extreme summer weather is the most likely cause of the rise.
Doctors have warned that as the world heats up Britain could be threatened by diseases such as malaria spreading north from the tropics.
In 2003, an estimated 2,000 UK deaths, mostly among elderly people, were attributed to the summer heat wave which was blamed on global warming.
But the record levels of legionnaires' disease reported by the Health Protection Agency this summer are believed to be the first example of an increase in infectious disease in Britain driven by climate change.
Legionnaires' disease is a bacterial infection spread through water.
It is not transmitted from person to person and can only be caught when infected water is inhaled as a vapour.
Hotel showers are a particular risk.
There were 128 cases of legionnaires' disease in August, the highest since records began in 1980 and more than double the total in August 2005 of 63 cases.
So far this year (to the end of September) there have been 340 cases, almost 100 more than in the whole of last year, and the highest figure for the first nine months of any year.
More than half these cases - 177 - occurred in August and September.
Public health experts investigating the leap in cases in August and September say changes in the climate are the chief suspect.
The hottest July on record, followed by a wetter than normal August are thought to have provided ideal breeding conditions for the legionella bacterium which causes the disease.
Carol Joseph, a specialist in the disease at the HPA, said previous peaks in the disease had been linked to single outbreaks, such as that in Barrow-in-Furness in 2002 when 179 people were infected by a leaking cooling tower.
But the latest cases cannot be traced to one or two outbreaks.
Dr Joseph said: "This latest peak [in August] is quite exceptional.
"We think this is some kind of weather effect.
"We had a very hot spell in July followed by a cooler, wetter August which possibly had an impact on the ecology of the bacteria."
The annual total of cases in Britain is on course to exceed 400 for the first time this year.
The total has exceeded 300 for the past five years, having remained below 200 for the previous 20.
Dr Joseph said improved reporting had contributed to the rise.
A spokesman for the Meteorological Office said July of this year had been the hottest since records began in 1659.
In August, temperatures fell, rainfall was 10 per cent above average and sunshine 15 per cent below average.
September was also the hottest since records began.
Asked if this was an effect of global warming, the MetOffice spokesman said:
"It is the sort of thing we would expect to see in accordance with the climate models."