Equatorward shift of marine heatwaves centroids in the Atlantic Ocean

Abstract

Ocean warming intensifies marine heatwaves (MHW) globally, increasing their frequency, intensity, duration, and extent, threatening marine ecosystems and economies. However, the latitudinal redistribution of MHW remains unquantified. Analyzing multisource data (1982–2023), we reveal a striking equatorward shift of MHW centroids (MHWC) at an average rate of ~1° latitude per decade across the northern and southern Atlantic basins, implying more frequent MHW in lower latitudes. This equatorial shift lacks seasonal phase-locking and is linearly independent of interannual climate variabilities known to influence the Atlantic variations. Mechanism analysis reveals that the Atlantic MHWC shift originates from the interplay between amplified tropical atmosphere-ocean positive feedbacks, which involve sea surface temperature, sea level pressure, and cloud-radiative interactions, and the concurrent weakening of equatorial and coastal upwelling. The attribution analysis shows anthropogenic warming is the dominant driver of this equatorward trend. The observed shift and rising MHW exposure in lower latitudes underscore the necessity for enhanced modeling fidelity at the regional scale, as this shift would worsen biodiversity loss and extreme events.