Climate change could REDUCE the likelihood of tropical cyclones: study shows frequency decreased by about 13% in 20th century
- Experts: Climate change seems to reduce the likelihood of tropical cyclones
- The annual number of such storms declined by 13 percent in the 20th century
- Australian researchers compared this period to a period between 1850 and 1900
- For most tropical cyclone basins, this decline has accelerated since the 1950s
Climate change appears to be reducing the likelihood of tropical cyclones around the world, researchers suggest.
They found that the annual number of such storms decreased by about 13 percent in the 20th century compared to the period between 1850 and 1900.
For most tropical cyclone basins, this decline has accelerated since the 1950s, which the new study’s authors say is largely due to a weakening of tropical atmospheric circulation.
It supports the theory that climate change is leading to a decrease in the number of tropical cyclones, they said.
Climate change appears to be reducing the likelihood of tropical cyclones around the world, researchers suggest. Pictured: a satellite image of Sam, the strongest tropical cyclone to form in the 2021 Atlantic hurricane season
However, experts led by the University of Melbourne warned that frequency is only one factor in the dangers of tropical cyclones.
They did not examine changes in intensity or location.
The researchers said it’s also not clear how cyclones change under human emissions, as a warming ocean is expected to intensify storms, while some changes in atmospheric circulation are thought to prevent storm formation.
As their name suggests, tropical cyclones have long had a distinctive feature of forming almost exclusively over low-latitude seas.
Key to these storms are warm sea surface temperatures of at least 81°F (27°C) and converging low winds that force the air to rise and form storm clouds.
As long as the nascent system is far enough from the equator, the planet’s spin interacts with the stream of moist, rising air, causing it to rotate cyclonically.
And just as cyclones don’t form too close to the equator, their range at higher latitudes is limited by the jet streams that have long confined them to the tropics.
As their name suggests, tropical cyclones have long had a distinctive feature of forming almost exclusively over low-latitude seas. Pictured: Typhoon Goni smashes the coast of central Philippines’ Sorsogon province on November 1, 2020
Key to tropical cyclone formation is warm sea surface temperatures of at least 27 °C (81 °F) and converging deep winds that force air to rise and form storm clouds. As long as the nascent system is far enough from the equator, the planet’s spin interacts with the stream of moist, rising air, causing it to rotate cyclonically. Pictured: The structure of a hurricane as seen in the Northern Hemisphere
Providing historical context for hurricane frequency is challenging because the observational records are incomplete, particularly prior to 1950, so experts used a combination of previous records and models.
Savin Chand and colleagues at Federation University Australia discovered declining trends in the annual number of tropical cyclones at both global and regional levels since 1850.
The only exception to this trend is the North Atlantic Basin, where tropical cyclone numbers have increased in recent decades.
The authors suggest that this may be because the basin is recovering from a late 20th-century decline in tropical cyclone numbers due to human-caused aerosol emissions.
However, the number of annual storms is still lower than in pre-industrial times, they added.
The study was published in the journal Nature Climate Change.
WHAT’S IN A NAME? CYCLONES VS HURRICANES VS TAIFONES
Pictured: Flooding in Houston, Texas, after Hurricane Harvey in 2017. Tropical cyclone can be called a hurricane because of the place on Earth where it struck
“Tropical cyclone” is the common name meteorologists give to rotating storm systems, also known as hurricanes, typhoons, tropical storms, cyclonic storms, and tropical depressions.
In particular, hurricane is the name given to these phenomena when they occur over the Atlantic or Northeast Pacific.
The term typhoon, on the other hand, refers to those that occur over the Northwest Pacific, South Pacific, Indian Ocean and – very rarely – over the South Atlantic.
Regardless of the name used, all feature a rapidly rotating storm system characterized by strong winds, a spiraling array of thunderstorms that produce both heavy rain and sudden gusts, all circulating around a center of low pressure — sometimes called the “eye” of the storm.