Researcher at Centre National de Recherches Météorologiques (CNRM)
Key takeaways
In January 2025, wildfires hit the Los Angeles region; analyses show that aridity and heat are among the factors contributing to these fires.
Scientists show that of the 103 droughts studied to date, 71 have been made more severe or likely by global warming.
Global warming affects droughts by modifying precipitation, reducing snow stocks in certain regions and increasing evapotranspiration.
While meteorological droughts are only slightly affected by global warming, we are seeing an increase in agricultural droughts around the world.
Without a drastic reduction in greenhouse gas emissions, it is likely that around a third of the world's land will suffer at best moderate drought by 2100.
Climatologist at Météo-France specialising in Water Resources
Bertrand Decharme
CNRS Research Director at Centre National de Recherches Météorologiques (CNRM)
Eric Sauquet
Research Director in Hydrology at INRAE
Key takeaways
In France, the spring of 2024 was the 4th wettest on record since 1959, raising questions about the link between rainfall and climate change caused by human activities.
However, there is no clear trend in overall annual rainfall at national level.
On a more limited geographical scale, however, there is an increase in winter rainfall in the northern half of the country and a decrease in summer rainfall in the southern half.
While rainfall is expected to increase in northern Europe because of climate change, the Mediterranean basin will become drier.
Between now and 2100, the projections do not foresee any clear trend in annual precipitation but indicate greater seasonal and regional disparities.
Research Director at the Dynamic Meteorology Laboratory (CNRS) and lecturer at Ecole Polytechnique (IP Paris)
Key takeaways
With global warming, periods of extreme rainfall are intensifying, but it remains difficult to predict future flood risks with any accuracy.
The Clausius-Clapeyron relationship shows that because of global warming, arid regions are becoming drier, while wet regions are becoming even wetter.
However, it remains difficult to precisely understand the impact of global warming on extreme precipitation, which is intermittent and varies from one geographical area to another.
All we know to anticipate flooding is that during periods of heavy precipitation, the intensity is increased by the presence of more water vapour in the atmosphere.
The risk of flooding depends not only on the climate, but also on the direct impact of human activities, such as soil sealing, which amplifies this risk, while certain hydraulic structures can reduce it.
Professor in Management of Innovation at Ecole Polytechnique (IP Paris)
Juan Diego Avila Hurtado
Master's Student at Ecole Polytechnique (IP Paris)
Hector Bonnel
Master's Student at Ecole Polytechnique (IP Paris)
Alexander Bracklo
Master's Student at Ecole Polytechnique (IP Paris)
Key takeaways
While water policies focus on visible water sources (blue water), it is vital to take into account the water stored in the soil and vegetation (green water).
Green water is the world's largest contributor of freshwater, and is necessary for terrestrial ecosystems, which can absorb 25-30% of the carbon dioxide emitted by fossil fuels.
Water evaporated from one region of a country can have a significant impact on rainfall in distant regions, as countries are interconnected via the hydrological cycle.
Water must be recognised as a global shared resource where the visible water resources, green water and atmospheric moisture fluxes of one country impact other countries around the world.
COP29 paved the way for a global water pact, highlighting the need to take into account the water-related issues of indigenous peoples, young people and migrants.
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