Heat waves to become more frequent and severe

Institute of Physics via Environmental Research Letters: Climate change is set to trigger more frequent and severe heat waves in the next 30 years regardless of the amount of carbon dioxide (CO2) we emit into the atmosphere, a new study has shown.

Extreme heat waves such as those that hit the US in 2012 and Australia in 2009 – dubbed three-sigma events by the researchers – are projected to cover double the amount of global land by 2020 and quadruple by 2040.

Meanwhile, more-severe summer heat waves – classified as five-sigma events – will go from being essentially absent in the present day to covering around three per cent of the global land surface by 2040.

The new study, which has been published today, Thursday 15 August, in IOP Publishing’s journal Environmental Research Letters, finds that in the first half of the 21st century, these projections will occur regardless of the amount of CO2 emitted into the atmosphere.

After then, the rise in frequency of extreme heat waves becomes dependent on the emission scenario adopted. Under a low emission scenario, the number of extremes will stabilise by 2040, whereas under a high emission scenario, the land area affected by extremes will increase by one per cent a year after 2040.

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

Europe's 2006 heat wave, data imaged by Giorgiogp2, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license