Global Warming.
September 17, 2019
According to new simulations, global warming looks much bigger than expected.
Global warming is expected to be more pronounced than expected, regardless of the efforts made to counter it, warned Tuesday French scientists who present new climate simulations that will serve as a basis for the IPCC. About a hundred researchers and engineers, including the National Center for Scientific Research (CNRS), the Atomic Energy Commission (CEA) and Météo-France, participated in this work. They will feed the sixth assessment report of the UN panel of experts on climate, scheduled for 2021-2022.
French scientists produced two different climate models, then subjected to several socio-economic scenarios. "In the worst case scenario, the overall average temperature rise reached 6.5 to 7° C in 2100," according to one presentation. This scenario is based on rapid economic growth fueled by fossil fuels. In the last IPCC 2014 report, the worst case scenario was + 4.8° C compared to the pre-industrial period.
Global warming issues
The most optimistic scenario, "marked by strong international cooperation and giving priority to sustainable development" allows to stay under the goal of 2° C warming, but "just", with "a mitigation effort (.. .) "and" at the cost of temporarily exceeding the 2° C target during the century ". The Paris Climate Agreement of 2015 plans to limit global warming well below 2 ° C, or even 1.5° C. Commitments so far taken by the states would lead to + 3° C.
The most optimistic scenario "implies an immediate reduction in CO2 emissions until reaching global carbon neutrality around 2060, as well as an atmospheric CO2 uptake of around 10 to 15 billion tonnes. per year in 2100", which technology does not currently allow. "The average temperature of the planet at the end of the century therefore strongly depends on climate policies that will be implemented now and throughout the 21st century," insist the CNRS, Météo-France and the CEA.
Image above: The evolution of the global average T ° C hides regional disparities shared by the two models @ meteofrance / Cerfacs and @ ipsl_outreach # climat @cea_officiel @CNRS.
This greater warming goes in the same direction as other foreign models. "This could be explained by a stronger climate response to the increase in anthropogenic greenhouse gases than in the 2012 simulations, but the reasons for this increased sensitivity and the degree of confidence in it still need to be assessed." according to a statement.
... but we can isolate a rhythmic elevation and in phase with the observations on the historical period, which gives some confidence in the models to represent the last 150 years.
Global atmospheric temperatures change. Image Credits: CNRS/CEA
French scientists had last bent on this exercise in 2012. Meanwhile, their tools have improved. "We have better models," said Olivier Boucher, director of research at CNRS, AFP. "As computing capacity increases, we have refined the resolution and we also have models that better represent the current climate."
Thanks to this finer scale, researchers have better modeled the consequences of global warming in Western Europe, by focusing on heat waves. "The intensity and frequency of heat waves have increased in recent decades" and "this trend will continue for at least the next two decades, regardless of the scenario considered".
Image above: Evolution of the #arctic icepack: probable summer disappearance at the end of the century # climat @cea_officiel @CNRS.
Related links:
CNRS: http://www.cnrs.fr/
CEA: http://www.cea.fr/english/Pages/Welcome.aspx
Images (mentioned), Text, Credits: AFP/CNRS/CEA/Orbiter.ch Aerospace/Roland Berga.
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