Climate: France’s future is worse than expected, according to a new study

In a medium-level emissions scenario, temperatures around 2100 will be 3.8°C above early 20th century temperatures.e century, i.e. 50% higher than expected.

By Guerric Poncet

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UA new study published in early October by a CNRS team on the future of climate in France is extremely worrying. Thanks to more precise calculations, researchers from the National Center for Meteorological Research (CNRM), the University of Toulouse and Meteo-France concluded that the temperature in 2100 would be 3.8 degrees in the scenario of average greenhouse gas emissions. above those of the early 20th centurye century It’s half as hot as expected so far.

It will be even worse in summer, as summers in 2100 will average 5 degrees above early 20th century temperatures.e century, still an average greenhouse gas emissions scenario. The latter is an optimistic assumption because it is intermediate between a sharp reduction in emissions and a continued increase in emissions on the current trajectory with very little probability and without strong containment measures.

READ ALSOWhy global warming will be more intense in France

A more subtle methodology

They do not represent the worst possible scenario, but these two numbers of + 3.8 and + 5 degrees are already synonymous with a major ecological shock that will destroy entire ecosystems and destroy millions of animal and plant species. Water will be acutely scarce in all regions. In addition to the threat to human health, the radical transformation of agriculture will make it impossible to preserve French terroir, from Burgundy wines to Alpine cheeses.

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These results were obtained by applying to a metropolitan area the methodology developed by the same French team and used on a planetary scale by the Intergovernmental Panel on Climate Change (IPCC) in its latest sixth report. This method of calculation has not been used before for any country-scale projections, and the projections for France are modeled on those made at the scale of continents or large regions.

It has already reached 1.66 degrees of warming

“The main innovation is the use of observed climate data to constrain the models,” the CNRS explains on its website. “Based on a series of climate simulations carried out using models used by the IPCC, the researchers determine what is consistent with temperature measurements collected over a period of more than a century. In this way, researchers can identify the most reliable predictions about the future of the climate and reduce uncertainties”, the CNRS continues.

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Metropolitan France is an excellent area to test this methodology on a national scale, as meteorological measurements have been reliably recorded there since 1899. Moreover, these data allowed us to accurately calculate the global warming that has already been achieved. it is 1.66 degrees, which is slightly higher than the world average for land areas (1.6 degrees).

The surprising effects of aerosols until the 1980s

Another discovery of the study is the large impact of aerosols, these particles suspended in the atmosphere and often caused by pollution, on the French climate. “We observe that until the 1980s, the effect of aerosols masked global warming, to the extent that it was almost invisible in the instruments,” explains Julien Boe from the Climate, Environment, Bounds and Uncertainties section. Research cited by CNRS.

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Obviously, pollution has had a positive effect by limiting global warming, until stricter regulations limit polluting emissions, at which point temperatures actually rise.

The French scientists hope that other researchers will model their country’s climate using the tools they have developed. “The code behind this work is available to anyone. This will allow other teams or other meteorological services to easily replicate these calculations for their own countries or regions,” explains Aurélien Ribes, lead author of the study from the CNRM.

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