Cyclone Chido leaves Mayotte reeling. Warmer oceans fueled it

The Indian Ocean archipelago of Mayotte is reeling from Cyclone Chido, the most intense storm to hit the French territory in 90 years.

At least 22 people have been killed since Chido made landfall on Saturday, as high winds swept away entire neighborhoods, damaged major infrastructure and uprooted trees.

And while Africa’s southeast coast is no stranger to devastating cyclones, climate scientists have warned in recent years that storms in the area are getting more intense and more frequent as a result of human-caused climate change.

When is cyclone season in southeast Africa?

Cyclone season in southeast Africa runs from December to March, when waters in the region are at their warmest. That’s because warm water fuels tropical storms so they tend to happen when oceans hit their peak temperatures for the year.

In recent years, devastating storms such as Cyclone Freddy in 2023, Batsirai in 2022 and Idai in 2019 all battered the southeastern coast of Africa — including swathes of Malawi, Mozambique, Zimbabwe and Madagascar — during southern hemisphere summer.

Cyclones are the same as hurricanes, but carry that name in the Indian Ocean and Australia.

How does climate change make cyclones worse?

Human-caused climate change, caused largely by the burning of coal, oil and gas, has heated up the planet: the atmosphere is now 1.3 degrees Celsius (2.3 Fahrenheit) warmer than pre-industrial times.

That matters because one ingredient for a cyclone, or hurricane, is warm water — at least 27 degrees Celsius (80 Fahrenheit), according to the United States’ National Oceanic and Atmospheric Association. With rising global temperatures, sea surface temperatures have reached all-time recorded highs. Chido was fed by ocean temperatures near 29 Celsius.

This warmer water can make the resulting storms more powerful, with stronger winds, heavier rainfall and more destructive storm surges.

In 2022, a group of climate scientists found that cyclones that pummeled southeast Africa that year were made worse by climate change. Because of a lack of weather data gathered in the region, they weren’t able to say by how much.

Shortage of early warning systems

Much of the African continent lacks the weather data and forecasting that other countries take for granted. Figures from the World Meteorological Organization estimate that the continent has just 37 radar facilities for tracking weather, compared to Europe’s 347 and North America’s 291.

It means that countries vulnerable to weather extremes are less prepared when deadly storms hit, so they can’t evacuate on time. Death tolls of the more devastating cyclones in recent years have gone into the hundreds — and 2019’s Idai saw over 1,000 people killed.

In 2022, the U.N. launched a project that aims to put every person in the world in range of early weather-warning systems within five years. The WMO’s secretary-general, Celeste Saulo, has made better access to weather forecasts a priority for the agency, calling adapting to climate change an “essential necessity.”

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