The misery of flooding is a reminder of the role of climate in overloading rainfall May 9, 2024

Aerial view of a flooded area of Porto Alegre, in the state of Rio Grande do Sul, Brazil, taken on May 8, 2024. (AFP)

By AFP - Agence France Presse

The misery of flooding is a reminder of the role of climate in overloading rainfall

Although not all of them are directly attributable to global warming, they are occurring in a year of record temperatures and emphasize what scientists have long warned about - that climate change creates more extreme weather conditions

PARIS: Floods have blazed a trail of destruction around the world, hitting Kenya, submerging Dubai, and forcing hundreds of thousands of people from Russia to China, Brazil, and Somalia from their homes.

Although not all of them are directly attributable to global warming, they are occurring in a year of record temperatures and emphasize what scientists have long warned about - that climate change generates more extreme weather conditions.

Climate change doesn't just refer to rising temperatures but to the indirect effect of all that extra heat being trapped in the atmosphere and seas.

April was the 11th month in a row to break its heat record, EU climate monitor Copernicus reported on Wednesday, while ocean temperatures have been off the charts for even longer.

“The recent extreme precipitation events are consistent with what is to be expected in an increasingly warmer climate,” Sonia Seneviratne, an expert on the UN's IPCC scientific panel, told AFP.

Warmer oceans mean more evaporation and warmer air can retain more water vapor.

Scientists even have a calculation for this: for every one degree Celsius increase in temperature, the atmosphere can retain seven percent more moisture.

“This results in more intense rainfall events,” Davide Faranda, an extreme weather expert at France's National Center for Scientific Research (CNRS), told AFP.

In April, Pakistan recorded twice the normal amount of monthly rainfall - one province recorded 437% more than average - while the United Arab Emirates received around two years' worth of rain in a single day.

This, however, doesn't mean that every place on Earth is getting wetter.

Richard Allan, from Reading University, said that “a warmer, thirstier atmosphere is more effective at sucking moisture out of one region and feeding that excess water into storms elsewhere”.

This translates into extreme rainfall and flooding in some areas, but worse heatwaves and droughts in others, the climate scientist told AFP.

Natural climate variability also influences the weather and global rainfall patterns.

This includes cyclical phenomena such as El Nino, which tends to bring extremes of heat and rain and helped fuel the high temperatures observed on land and at sea last year.

Although natural variability plays an important role, “the observed long-term global increase in heavy precipitation has been driven by human-induced climate change,” said Seneviratne.

Carlo Buontempo, director of Copernicus, said that cycles like El Nino have an ebb and flow, but the extra heat trapped by increased greenhouse gas emissions “will continue to push global temperatures to new records”.

Considering the overlapping forces at play, attributing any flood to climate change alone can be tricky, and each event must be analyzed on a case-by-case basis.

However, scientists have developed peer-reviewed methods that allow a quick comparison of a current event with simulations that consider a world in which global warming had not occurred.

For example, World Weather Attribution, the scientists who pioneered this approach, said that the flooding in the United Arab Emirates and Oman last month was “very likely” exacerbated by global warming caused by burning fossil fuels.

Cars drive past a flooded highway in Dubai on April 20, 2024. Four people died after the heaviest rain ever recorded in the oil-rich United Arab Emirates on April 16. (AFP)

ClimaMeter, another rapid assessment network that uses a different methodology, said that the major floods in China in April were “probably influenced” by global warming and El Niño.

“It can be difficult to separate global warming from natural variability” and some climate events are clearer than others, said Flavio Pons, a climatologist who worked on the China assessment.

In the case of the devastating floods in Brazil, however, ClimaMeter managed to exclude El Nino as a significant factor and point to man-made climate change as the main culprit.

Many of the countries inundated by major floods at the moment - such as Burundi, Afghanistan, and Somalia - are among the poorest and least able to mobilize a response to such disasters.

But the experience in Dubai showed that even rich countries were unprepared, said Seneviratne.

“We know that a warmer climate is conducive to more severe weather extremes, but we can't predict exactly when and where these extremes will occur,” Joel Hirschi, from the UK's National Oceanography Center, told AFP.

“Current levels of preparedness for climate extremes are inadequate... Preparing and investing now is cheaper than delaying action.”

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