Scientists are sounding the alarm about the impact of climate change on hurricanes like Idalia, which quickly strengthened in the Gulf of Mexico before making landfall Wednesday in Florida.
Here is what we know about the effects of climate change on these phenomena.
In May, the US Oceanic and Atmospheric Observation Agency (NOAA) predicted a “near-normal” Atlantic hurricane season.
This prediction was largely based on the existence of the El Nino climatic phenomenon. It defuses the formation of hurricanes by increasing the vertical circulation of the wind, which causes cold air to descend.
Importing this “dry, less energy-laden air” into the heart of a tropical cyclone “prevents it from strengthening,” Allison Wing, a scientist at Florida State University, told AFP.
But in August, the US agency adjusted its forecast upwards, announcing that the season would be “above normal”, based on ocean and atmospheric conditions. The “record surface temperatures in the Atlantic” will probably offset the effects of El Nino, unfavorable to hurricanes, she explained.
“In terms of forecasting the season, it’s a complicated year because we have these two contradictory factors,” said Allison Wing.
On July 24, a buoy off the southern tip of Florida recorded a temperature of 38.4 degrees, more easily associated with a hot tub than the ocean, and which could be a world record.
“Warm waters, both on the surface of the ocean and in the depths, act as a fuel that intensifies tropical storms and hurricanes,” says Michael Mann, a climatologist at the University of Pennsylvania. “This allows them to build strength faster and reach higher peak power.”
The formation of a hurricane requires a set of precise conditions – but when they come together, the heat of the oceans allows them to generate stronger winds and higher tides.
“You could say that climate change sucks the dice,” adds Allison Wing. “Very different scenarios remain possible for each storm, but the probability of a very intense storm is higher.”
Climate change can also increase the amount of rain carried by hurricanes, according to Andrew Kruczkiewicz, a researcher at Columbia University’s Research Institute for Climate and Society.
“The warmer the atmosphere, the greater the capacity to absorb water,” which can mean more precipitation, he says. Residents who fled inland to escape a hurricane could still face extreme conditions, adds the expert.
Rainfall during Hurricane Ian in September 2022 was enhanced by at least 10% due to climate change, according to recent research.
Beyond the intensity of the storms, it is the season in which they occur that seems to be getting longer.
The period when ocean surface temperatures favor the formation of tropical storms begins earlier and ends later, according to Michael Mann. This seems to be true in the Atlantic as well as in the Bay of Bengal.
A wealth of work shows that climate change is making hurricanes more dangerous, but its effect on their frequency is less clear, and more research is needed to understand this.
31/08/2023 07:16:20 – Washington (AFP) – © 2023 AFP
