Hotter, more often, earlier and later. Multiplying heat waves like the one currently engulfing much of Western Europe or the one that hit India in March-April 2022, are clear signs of climate change, scientists explain.

Globally, the years since 2015 have been the hottest on record. And well-timed heatwaves are multiplying everywhere in the world, with a procession of catastrophic consequences, droughts, fires, and of course, loss of human life.

Human responsibility

“Every heat wave we experience gets hotter and more frequent due to human-caused climate change” summarizes Friederike Otto, of the Grantham Institute at Imperial College London.

“This is pure physics: we know how greenhouse gas molecules behave, we know there are more molecules in the atmosphere, that the atmosphere is getting warmer, which means we expect to see more frequent and warmer and less frequent and colder heat waves. ” explained during an online briefing this specialist in the “attribution” of extreme events to climate change.

This growing branch of climate science has calculated that heat waves of unprecedented intensity and speed that hit India and Pakistan in March-April 2022 were made 30 times more likely by climate change.

Or a massive heatwave in Canada in June 2021, which will kill more than 500 people at temperatures close to 50°C. ” almost impossible “ without climate change. Or that warming has added up to 3ºC to Europe’s very strong summer heatwave in 2019.

“The increase in the frequency, duration and intensity of these (heatwave) events in recent decades is clearly related to observed global warming and can be attributed to human activities” The World Meteorological Organization abounded on Monday in commentary on the extreme heat in Western Europe.

The worst is yet to come

And it’s not over yet. According to UN climate experts, an extreme heat wave will have 4.1 times more the “opportunity” of intervention at +1.5ºC average global warming compared to the pre-industrial era, the most ambitious goal of the 2015 Paris agreement.

They will be 5.6 times more likely at +2°C and 9.4 times more likely at +4°C. For more intense and rare heat peaks, the figure increases to 8.6 times more at +1.5ºC, 13.9 times at +2ºC and… 39.2 times at +4ºC!

But the planet has won close to 1.2ºC roughly since the industrial revolution and, according to the United Nations, the current commitments of countries, if respected, will lead to global warming “disaster” +2.7ºC.

The climate cycle is thus highly modified, as Matthieu Sorel, a climatologist at Météo France, notes that the country’s escalating heatwave – for the past two years – will decrease in intensity by 1.5ºC to 3ºC without the effects of climate change. . “We are heading into a hotter summer, where 35ºC will be the norm and 40ºC will be achieved regularly” he warned.

Disaster Consequences

Humans will be increasingly affected by this heat, which can be fatal: 14% human would be affected by the consequences of global warming at least once every five years at +1.5°C but 37% at +2°C, according to the IPCC.

Gold, “Everywhere in the world where we have data, there is an increased risk of death when we are exposed to high temperatures. (…) And the more extreme these temperatures, the higher the risk” warns Eunice Lo of the Cabot Institute for the Environment at the University of Bristol.

And “It is not only vulnerable people who are at risk of health impacts, even healthy and fit people are at risk” emphasize specialists.

Until you die, especially from the “wet bulb” effect, when the moisture contained in the hot air prevents the body from sweating and thus releasing its own heat.

The effects are also damaging to the environment, with heatwaves amplifying droughts, favorable grounds for fires, such as those currently engulfing France, Portugal, Spain, Greece and Morocco.

They can also threaten human food. Hit by a heatwave, India, the world’s second-largest wheat producer, imposed a temporary embargo on exports of this cereal, amplifying the crisis sparked by Russia’s invasion of Ukraine.

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