Observed Global Increases in Tropical Cyclone Induced Ocean Cooling and Primary Production

Tropical cyclones provide an important source of ocean mixing, bringing cold, nutrient rich water to the surface and triggering phytoplankton blooms. Here, we show significant increases in global tropical cyclone induced sea surface temperature cooling and surface chlorophyll a concentration of 0.05°C and 3.7 × 10⁻³ mg m⁻³ per decade over the past 20-35 years. The trends have been driven primarily by an increase in the intensity of strong tropical cyclones. The increase in chlorophyll a concentration has been, on average, 1.6% per decade in oligotrophic areas during the tropical cyclone season, in contrast to a decrease of 0.1% per decade during the other months. This tropical cyclone induced increase has partially mitigated the overall decline in primary production under climate change.