A team of researchers at LSCE (ESTIMR) and LMD simulated what could be an extreme 15 heatwave before 2050.This research is led by Pascal YIOU (LSCE-IPSL, CEA) and involves Camille Cadiou, Davide Faranda, Aglaé Jézéquel, Nemo Malhomme, George Miloshevich, Robin Noyelle, Flavio Pons, Yoann Robin & Mathieu Vrac
Reference: Pascal Yiou et al. (2023) “Ensembles of climate simulations to anticipate worst case heatwaves during the Paris 2024 Olympics“, npj Clim Atmos Sci 6, 181. https://doi.org/10.1038/s41612-023-00500-5
The Paris Olympics in 2024 will take place between July 26th to August 11th 2024, at the apex of the temperature seasonal cycle. Can the deadly 15-day temperature record of 2003 be broken in the present decades? How hot can it be in the Paris area?
A team of researchers at LSCE (ESTIMR) and LMD simulated what could be an extreme 15 heatwave before 2050. They applied a rare event algorithm to climate simulations from the CMIP6 project, to obtain an ensemble of the most intense 15-day heatwaves in the Paris area that are reachable with various emission scenarios, with plausible physical conditions.
They showed that the 2003 record can be broken by several °C before 2050 (red boxplots), but such values can hardly be reached in the 20th century (blue boxplots). It appears that such extreme heatwaves require a stable anticyclonic condition. High temperature can be exacerbated by an atmospheric “cut-off low”, which conveys warm air from North Africa into Europe.
This study is not a forecast for 2024, but a warning on the possibility of intense heatwaves during the present decades.
Figure 1 – Extreme 15 day heatwave simulations (TG15d) using the IPSL model in SSP1-2.6, SSP2-4.5 and SSP3-7.0 simulations. Brown horizontal lines are the value observed in 2003. Orange horizontal lines are highest values in the IPSL model. Boxplots are the 1000 “extreme” simulations with conditions in the 20th century (blue) and 2001-2050 (red).