The intensity of extreme events linked to the water cycle – such as droughts and floods – is strongly correlated with average temperatures around the world, so they will become even more severe with global warming, underlines a study published on Monday and which is based on unpublished data.
The scientists, based in the United States, used an innovative method, using data collected by satellites to study extreme hydroclimatic events. Until now, studies have relied mainly on rainfall figures.
In a study published in the journal Nature Water, the researchers used data for the years 2002-2021 to better quantify the impact, already known in theory but poorly measured, of global warming on these extreme events.
“The total intensity of extreme events has been strongly correlated with global average temperatures”, more than with any other climatic factor (such as the phenomenon El Niño / La Niña), conclude the authors.
This intensity refers to the extent, duration and severity of events.
Since 2015, the frequency of the most extreme events has also increased to 4 per year, compared to 3 per year over the previous 13 years.
“This suggests that for the future, as the world continues to warm, we can expect to see more frequent and severe episodes of drought and precipitation,” NASA’s Matthew Rodell told AFP. co-author of the study.
The world has already warmed by almost 1.2°C since the pre-industrial era as a result of human activity and in particular the use of fossil fuels such as oil and coal. Without a strengthening of current policies, the world is heading, according to UN climate experts (IPCC), towards a warming of +3.2°C by 2100.
“Droughts and floods were predicted to become more frequent and severe with climate change, but this was difficult to measure,” said Matthew Rodell.
Until now, the link was based on climate models and an observation: hot air results in more evaporation during periods of drought but also allows larger masses of water to move during episodes of precipitation.
The study now provides “strong evidence” of the link with global warming, based on satellite observations collected on terrestrial water supplies, on the ground and on the surface of it, estimates the researcher.