Extreme heat waves such as those that hit the United States in 2012 and Australia in 2009 are projected to cover double the amount of global land by 2020 and quadruple by 2040, scientists report in the journal Environmental Research Letters of the Institute of Physics in London.
In the first half of the 21st century these projections will occur regardless of the amount of CO2 emitted, they said.
"We find that up until 2040, the frequency of monthly heat extremes will increase several-fold, independent of the emission scenario we choose to take," lead study author Dim Coumou from the Potsdam Institute for Climate Impact Research in Germany said. "Mitigation can, however, strongly reduce the number of extremes in the second half of the 21st century."
The researchers used state-of-the-art climate models to project changes in the trend of heat extremes throughout the 21st century.
"Heat extremes can be very damaging to society and ecosystems, often causing heat-related deaths, forest fires or losses to agricultural production," Coumou said. "So an increase in frequency is likely to pose serious challenges to society and some regions will have to adapt to more frequent and more severe heat waves already in the near-term."