Heatwaves that erase temperature records like in western Canada last month and Siberia last year are caused by the rapid pace, rather than the magnitude, of global warming, researchers said Monday .
The findings, reported in Nature Climate Change, suggest that humanity is likely to see many more deadly burns in the decades to come.
“Because we are in a period of very rapid warming, we have to prepare for further episodes of heat which largely shatter previous records”, lead author Erich Fischer, senior scientist at ETH Zurich and lead author of the UN Climate Science Assessment. currently under review, AFP told AFP.
The heat wave that swept through British Columbia saw temperatures soar to 49.6 degrees Celsius (121 degrees Fahrenheit), more than five degrees above the hottest day on record in Canada so far.
Current rates of warming – about 0.2 degrees Celsius per decades – are expected to continue for at least 10 to 20 years, regardless of how quickly humanity is reducing the carbon pollution that causes global warming, warns l ‘study.
But efforts to reduce greenhouse gases over the next decade will pay off later.
“The future likelihood of extreme highs depends on the path of emissions that takes us to a given level of warming,” Fischer said.
So far, research on the impact of global warming on heat waves has mainly focused on increasing temperatures relative to a baseline period rather than speed.
This is, of course, of crucial importance, and science has no doubt shown that a warmer world will produce more and warmer heat waves.
But ignoring how quickly temperatures rise fails to capture a key part of the image.
– Climate on steroids –
“Without climate change, one would expect record temperatures to become scarce as we measure for a long time,” Fischer explained.
Likewise, if average global temperatures stabilize at, say, 1.5 degrees Celsius above mid-19th century levels, the ambitious goal of the Paris Agreement, spectacular new records would gradually become less frequent.
Fischer compares it to athletics, where the longer a discipline has existed, the harder it is to break a world record. Long jump and high jump records, for example, have been around for decades, or are never broken more than an inch or two.
# photo1 But if athletes start taking performance enhancing drugs, as happened in American baseball in the late 1990s, records are suddenly broken, often and in a big way.
“The climate is behaving like an athlete on steroids right now,” Fischer said.
At current rates of greenhouse gas emissions, the world is on track to continue to warm to current rates above 3 ° C by 2100.
“This is a very important study,” commented Tim Palmer, a research professor at the University of Oxford who was not involved in the results.
But climate models with much higher resolution – like a camera with 64 megapixels instead of 16 – are needed to simulate the monstrous heat waves seen around the world over the past 20 years.
“This new study highlights the high potential of extreme records,” including the type of extreme precipitation that plagued Germany and China earlier this month, noted Rowan Sutton, professor at the National Center for Atmospheric Science of the University of Reading. , in Great Britain.
“Although it does not seem fast to us, the Earth is warming at a rate unprecedented in the history of human civilization. “
© 2021 AFP