Study: Tropical Cyclone Frequency Decreasing As Earth Mildly Warms

by S. Chand et al., Jun 28, 2022 in ClimateChangeDispatch

Assessing the role of anthropogenic warming from temporally inhomogeneous historical data in the presence of large natural variability is difficult and has caused conflicting conclusions on the detection and attribution of tropical cyclone (TC) trends. [bold, links added]

Here, using a reconstructed long-term proxy of annual TC numbers together with high-resolution climate model experiments, we show robust declining trends in the annual number of TCs at global and regional scales during the twentieth century.

The Twentieth Century Reanalysis (20CR) dataset is used for reconstruction because, compared with other reanalyses, it assimilates only sea-level pressure fields rather than utilizing all available observations in the troposphere, making it less sensitive to temporal inhomogeneities in the observations.

It can also capture TC signatures from the pre-satellite era reasonably well.

The declining trends found are consistent with the twentieth-century weakening of the Hadley and Walker circulations, which make conditions for TC formation less favorable.

Human activities are estimated to have caused ~1.0 °C of global warming above pre-industrial levels, with most of the warming occurring since the mid-twentieth century1.