Observed Regional Impacts of Marine Heatwaves on Sea-Air CO2 Exchange

Abstract

Marine heatwaves (MHWs) have devastating effects on ecosystems. Yet a global assessment of the regional impacts of MHWs on the sea-air (Formula presented.) exchange is missing. Here, we analyze 30 global observation-based sea-air (Formula presented.) flux data sets from 1990 to 2019. Globally, the oceanic (Formula presented.) uptake is reduced by 8% (3%–19% across data sets) during MHWs. Regionally, the equatorial Pacific experiences a 31% (3%–49%) reduction in (Formula presented.) release and MHWs often coincide with extreme sea-air (Formula presented.) flux anomalies in this region. The oceanic (Formula presented.) uptake decreases during MHWs by 29% (19%–37%) and 14% (5%–21%) in the low-to-mid latitude Northern and Southern Hemisphere, respectively. Reduced dissolved inorganic carbon in the tropics weakens outgassing, while high ocean temperatures diminish uptake in the low-to-mid latitudes. In the subpolar North Pacific and Southern Ocean, enhanced carbon uptake occurs during MHWs, but uncertainties in p (Formula presented.) data sets limit a comprehensive assessment in these regions.