Areas affected by extreme heatwaves will double in size by 2020.

20 August 2013 — A new study has found that heatwaves will become more frequent and severe, regardless of how much CO2 is emitted into the atmosphere.

Reporting in Environmental Research Letters, the study authors found that extreme heatwaves, like the one Australia experienced in 2009, would cover double the amount of land globally by 2020 and quadruple by 2040.

More severe heatwaves – five-sigma events – would go from being non-existent to affecting three per cent of global land by 2040.

After 2040, the frequency and severity of heatwaves would be dependent on global greenhouse gas emissions.

Under a low emission scenario, extreme heatwaves would stabilise by 2040. Under a high emission scenario, the land area affected by extremes would increase by one per cent a year.

“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,” said study lead author Dim Coumou from the Potsdam Institute for Climate Impact Research. “Mitigation can, however, strongly reduce the number of extremes in the second half of the 21st century.”

The research found that tropical regions would see the greatest increase in heat extremes.

“Heat extremes can be very damaging to society and ecosystems, often causing heat-related deaths, forest fires or losses to agricultural production,” said Coumou. “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.”