Climate change has locked the world into more frequent and severe heatwaves in the next few decades, researchers said.
There will be a “several-fold” increase in heatwaves up to 2040, regardless of how much carbon dioxide goes into the atmosphere, but future efforts to slash pollution could stem the rise in extreme heat events later on in the century.
The last decade has seen an exceptional number of extreme heatwaves around the world, hitting the US in 2012, Russia in 2010, Australia in 2009, and Europe in 2003 with damaging impacts on health, the economy, agriculture and wildlife.
The soaring monthly and seasonal temperatures associated with heat waves can now largely be attributed to global warming of around 0.5˚C over the past 50 years, according to a study published in the Institute of Physics’ journal Environmental Letters.
Extreme summer heatwaves in which monthly temperatures soar well above norms now cover around five per cent of the world’s land, mostly in the Tropics but also over western Europe and the Mediterranean, the researchers said.
But the percentage of land experiencing summer months of extreme heat is set to double by 2020, and quadruple by 2040 to cover a fifth of the global land surface, the projections using computer climate models found.
Even more severe summer heatwaves will increase from being virtually non-existent today to covering around three per cent of the world’s land. The increase in heatwaves takes place regardless of efforts to cut emissions in the next few decades.
After 2040, the frequency of extreme heat events is affected by whether or not the world takes action to slash greenhouse gases. If there are only low emissions, the frequency of periods of extremely hot weather will remain constant after 2040.
In Europe, around a fifth of summer months will record temperatures well above the seasonal norms, though the most extreme heatwaves will be essentially absent, the scientists said.
But with high emissions of carbon dioxide going into the atmosphere, heatwaves will continue to increase, and by 2100 monthly heat extremes will cover around 85 per cent of the world’s land area and very severe heat events will occur over 60 per cent of the land.
The study’s lead author Dim Coumou, from the Potsdam Institute for Climate Impact Research in Germany, said: “We find that up until 2040, the frequency of monthly heat extremes will increase several fold, independent of the emissions scenario we choose to take.
“Mitigation can, however, strongly reduce the number of extremes in the second half of the 21st century.”
He said that a good example of the extreme heatwaves the world is facing were the conditions in Russia in 2010 where the average temperature around Moscow in July was 7˚C above normal at around 25˚C. In some places temperatures soared to 40˚C.
“Heat extremes can be very damaging to society and ecosystems, often causing heat-related deaths, forest fires or losses to agricultural production.
“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 heatwaves already in the near-term,” he said.