It is a term that appears more and more in scientific reports but also in political debates. the one ofexceedwhich in the climate context takes the meaning of “overcome and return” in French, that is, the idea that after having crossed the limit of 1.5°C of warming, countries would achieve, with the help of big technologies, return to this threshold. , considered to avoid the maximum deadly impacts of climate change. Thus, the world would respect, in the long term, the 2015 Paris agreement, which targets this temperature. In reality, this excess carries many risks and would not prevent certain irreversible consequences of climate change, according to an extensive study published in Nature Wednesday, October 9. In summary, a complete return to the past is impossible.
“The notion ofexceed gains ground as the world moves towards [une augmentation moyenne de la température de] 1.5ºC »says Carl-Friedrich Schleussner, lead author of the study and climate scientist at the International Institute for Applied Systems Analysis (Austria). The planet has already warmed 1.3°C since the pre-industrial era, causing a procession of floods, heat waves and fires. “But even if we managed to lower the global temperature after crossing this threshold, the climate and the world would not be the same as before”warns. There “Only way to limit the damage”According to him, it now remains to reduce greenhouse gas emissions to prevent warming from becoming too serious.
The 1.5°C limit should be exceeded in the early 2030s, according to the latest report from the Intergovernmental Panel on Climate Change (IPCC), which had only touched on the notion ofexceed. New work published in NatureConducted over three and a half years by 30 EU-funded scientists, it explores for the first time a multitude of overshoot scenarios – including the current warming trajectory of almost 3°C by 2100 – and their short- and very long-term impacts. long-term (until 23:00).
“Overconfidence”
Thus, even if the temperature dropped, certain impacts of global warming would be irreversible, on a global scale or in certain regions. This is the case of increased mortality due to heat waves, species extinctions, economic losses, disappearance of glaciers, melting of permafrost (soils that are always frozen) or even the destruction of peatlands. TO exceed It would also increase the likelihood of tipping points, such as the disappearance of the Greenland and West Antarctic ice sheets or the extinction of the Amazon.
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