Research: Global warming contributed to decline in tropical cyclones in the 20th century

Hurricane Humberto spins over the Atlantic Ocean on September 15, 2019. Credit: NOAA

The annual number of tropical cyclones forming globally has decreased by approximately 13% during the 20th century, and scientists say the main cause is a rise in global warming, according to a new study in Nature Climate Change by a group of international scientists including NOAA scientists.
Scientists used reconstructed observatation data, including the Twentieth Century Reanalysis dataset developed by NOAA’s Physical Sciences Laboratory and partners, as well as high-resolution climate model experiments to reveal the declining trend in the annual number of tropical cyclones since 1850 at both global and regional scales. 

The global annual number decreased by 13% in the 20th century when compared to the period between 1850 and 1900. For most ocean basins, the decline accelerated since the 1950s, when climate warming has been unprecedented.

“Human emissions have warmed tropical oceans above pre-industrial levels, with most warming occurring since the mid-twentieth century,” said lead author Savin Chand, Ph.D., of the Federation University of Australia. “While such changes in sea surface temperature are expected to intensify storms, some associated changes in atmospheric circulations in the tropics are thought to prevent storm formation.”

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