The ocean is a major sink of anthropogenic carbon, absorbing 20~30% of anthropogenic CO2 emissions across the air–sea interface. Intense weather systems, such as tropical cyclones, can strongly perturb the upper ocean and thus critically influence this carbon transfer. Here we develop an approach of synthesizing various observations to quantify the role of tropical cyclones in the global carbon cycle. Two primary, but competing effects are: (1) CO2 efflux (from the ocean to atmosphere) during tropical cyclone passage and (2) CO2 influx after tropical cyclones, associated with disturbed carbon disequilibrium by mixing upwards of colder water (cold wakes). The CO2 efflux more than offsets the influx, resulting in net ocean carbon outgassing to the atmosphere. Annual tropical cyclone-induced carbon outgassing has decreased over the past three decades, from 0.09 ± 0.02 PgC in the 1990s to 0.05 ± 0.01 PgC in the 2010s. A strengthening of the vertical temperature gradient in the upper ocean due to anthropogenic climate warming leads to cold wakes with more intense surface cooling and increased carbon uptake after tropical cyclones. This has implications as the vertical temperature gradient continues to grow under high-emissions scenarios, tropical cyclones will cause net increasing ocean carbon uptake and more severe ocean acidification.
Ye H., Ma Z., Fei J., Trenberth K. E., Tanhua T. & Cheng L., 2026. Reduction of tropical cyclone-induced ocean carbon outgassing since 1993. Nature Geoscience. Article.
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