London – Three-quarters of the extremely hot days in the world are now being influenced by man-made global warming and nearly one in five days of heavy rainfall are due to human influences on the climate, scientists said.
For the first time, researchers have put figures to the effect on the world's weather extremes as a result of the extra greenhouse gases being put into the atmosphere from the burning of fossil fuels.
By combining data used by 25 computer models of the global climate for the period 1901 to 2005, two scientists from Zurich University in Switzerland calculate that 75 per cent of daily heat extremes and 18 per cent of heavy rainfall or snowfall is now being driven by the human activity that has contributed to an increase in global average temperatures of 0.85C over the past century.
Erich Fischer and Reto Knutt suggested that the rarest and most extreme hot or wet days around the world are likely to be influenced by warming caused by extra Co2 in the atmosphere.
“Climate change doesn’t cause any single weather event in a deterministic sense. But a warmer and moister atmosphere does clearly favour more frequent hot and wet extremes,” Dr Fischer told Nature Climate Change, where the study was published.
They also predict that if global average temperature increases by 2C, the proportion of extremes in heat attributed to climate change will increase from 75 to 96 per cent, while the extremes in rainfall will increase from 18 to 40 per cent.
Peter Stott, a climate researcher at the Met Office Hadley Centre, said that as each year passes the evidence for man-made influences on the global climate is mounting.
“The idea that in a 2C world almost half of heavy rainfall events would not have occurred were it not for climate change is a sobering thought for policymakers seeking to mitigate and adapt to climate change,” he said.
The Independent