Scientists who a decade ago found that global warming had doubled the risk of an extremely hot summer in Europe have reported that such an event is now 10 times likelier.
In 2004, experts at Britain's Met Office calculated that man-made carbon emissions had doubled the risk of an extreme summer heatwave when compared to the historical average.
Statistically speaking, such an event - defined as temperatures 1.6 degrees above the 1961-1990 average for June-August - would occur every 52 years.
In the new study, the same team revisited the scenario in light of a surge of warming since then, using better computer models to crunch the data.
Under today's conditions of warmth, the heatwave would occur roughly twice every decade, not twice a century, they found.
The research, published in the journal Nature Climate Change, focused as before on France, Germany and Italy.
These were the countries that in 2003 bore the brunt of Europe's hottest summer since reliable records began.
Some estimates put the death toll at about 30,000, but a study in 2008 suggested more than 70,000 people in 16 countries died as a result of the heatwave.
Reservoirs and rivers ran low or dried up, food prices rose because of livestock deaths and crop losses, forest fires broke out in southern Portugal and Spain, and melting snow and glaciers in the Alps caused rock falls.
In their 2004 appraisal, the British scientists found that a 2003 event - whose temperature was a whopping 2.3 degrees above the long-term average - was statistically likely to occur on scales of a thousand years or more.
Their latest assessment put the likelihood at nearly once a century - every 127 years.
Temperatures in Western Europe were 0.81 C warmer in the decade of 2003 to 2012 compared to 1990-1999, a rise overwhelmingly ascribed to man-made carbon gases.
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