All heat waves already bear the measurable and characteristic imprint of global warming, scientists specializing in the link between extreme weather events and climate change assured on Wednesday May 11.
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Warming caused by human activities is also increasing the frequency and intensity of floods in some parts of the world and of some droughts, but the link is less systematic, according to the document published on Wednesday and presented as a guide for journalists. .
“
There is no doubt that climate change is changing the rules of the game when it comes to heat waves
,” one of the authors, Friederike Otto, from Imperial College London, told AFP.
“
Every heat wave in the world today is stronger and more likely to occur due to human-induced climate change
,” insist the researcher and her co-author Ben Clarke, from the University of Oxford, in the document.
So "
don't be too careful
", heat waves are "
linked to global warming
", they tell the media covering these heat waves.
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1.2°C warmer compared to the pre-industrial era
Until recently scientists were reluctant to formally link a particular event to climate change, but so-called attribution science has made tremendous progress in recent years, making it possible to identify and quantify the responsibility for warming in an event. weather, sometimes within days.
For example, Friederike Otto and her colleagues at World Weather Attribution estimated that the extraordinary heat wave episode that hit North America in June 2021, with a record 49.6°C in Canada, would have been "
almost impossible
without the warming.
The heat wave this spring in India and Pakistan is still being analyzed but "
what we see now will be normal, even cold, in a world between +2° and +3°C
", comments Friederike Otto .
For the moment, the world has gained nearly 1.2°C on average compared to the pre-industrial era.
But warming is not necessarily equally culpable in all extreme events, other than heat waves.
Experts insist on the need to take into account the role played by other factors in certain disasters (territorial planning, water management, etc.).
And sometimes climate change has nothing to do with it.
Thus, experts from the World Weather Attribution estimated that warming played only a minimal role in the exceptional drought and famine that hit Madagascar from 2019 to 2021: the projected increase in droughts on this island is predicted by climate models from +2°C.