The chances of extremely hot summers in parts of Europe have risen tenfold this century because of man-made global warming, a study by British scientists said.

Average summers in an area covering Central and Mediterranean Europe have warmed considerably, far faster than the global average and adding to risks of severe heatwaves, according to the study in the journal Nature Climate Change.

The report, released during United Nations talks in Lima on a deal to combat global warming, said the rising heat meant an extremely warm summer, which had been expected once every 50 years in the early 2000s, could now be anticipated every five years.

The study defined an extreme summer as one that is 1.6˚C above the average for 1961-1990. In the last decade, average summers in Europe have warmed by 0.81˚C, it said.

“Our vulnerability to heat extremes is rapidly changing, and we expect that to continue,” study co-author Peter Stott of the British Met Office said in a statement.

The UN’s weather agency said last week that world temperatures this year were on track to be the hottest, or among the very warmest, on record.

Stott led a study in 2004 that concluded man-made global warming had doubled the risks of an extreme heatwave like one that struck Europe in 2003.

That hot spell, believed to be the most severe in 500 years, killed about 70,000 people, hitting France hardest.

Since the early 2000s, chances of such a heatwave had risen to about one in 100 years from about one in 1,000, the study said.