Next 30 years to see more frequent heat waves

WASHINGTON: Climate change is set to trigger more frequent and severe heatwaves in the next 30 years regardless of the amount of carbon dioxide (CO2) emitted into the atmosphere, a new study has warned.


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, researchers said.

Meanwhile, more-severe summer heat waves — classified as five-sigma events — will go from being essentially absent in the present day to covering around 3% of the global land surface by 2040, they said.

The study, published in the journal Environmental Research Letters, found 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 stabilize by 2040, whereas under a high emission scenario, the land area affected by extremes will increase by 1% a year after 2040, researchers 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,” lead author of the study, Dim Coumou , from the Potsdam Institute for Climate Impact Research , said.

Under a high-emission scenario, the projections show that by 2100, 3-sigma heat waves will cover 85% of the global land area and fivesigma heat waves will cover around 60% of global land.

In the study, Coumou, and Alexander Robinson, from Universidad Complutense de Madrid, used state-of-the-art climate models to project changes in the trend of heat extremes under two future warming scenarios throughout the 21st century.