Impact of Marine Heatwaves on Air‐Sea CO<sub>2</sub> Flux Along the US East Coast
Kelsea Edwing, Zelun Wu, Wenfang Lu, Xinyu Li, Wei‐Jun Cai, Xiao‐Hai Yan
Abstract
Abstract Marine heatwaves (MHWs) are extremely warm ocean temperature events that significantly affect marine environments, but their effects on the coastal carbonate system are still uncertain. In this study, we systematically quantify MHWs' impacts on air‐sea carbon dioxide (CO 2 ) flux anomalies (FCO 2 ′) in the Mid‐Atlantic Bight (MAB) and South Atlantic Bight (SAB) from 1992 to 2020. During the longest MHW in both regions, oceanic CO 2 uptake capabilities substantially decreased, primarily due to significant increases in the seawater partial pressure of CO 2 ( p CO 2sea ). For all cases, MHWs played a more significant role in driving p CO 2sea changes in the MAB than the SAB, where non‐thermal drivers dominated p CO 2sea variability. In the MAB, weakened wind speeds related to wintertime atmospheric perturbations increase ocean temperatures and p CO 2sea , further reducing CO 2 uptake during winter MHWs. This work is the first to connect extreme temperatures to coastal air‐sea CO 2 fluxes. The reduction in CO 2 absorption noted during MHWs in this study has important implications for coastal regions to act as continued sinks for excess CO 2 emissions in the atmosphere.