Emergence of the enhanced equatorial Atlantic warming as a fingerprint of global warming

The response of tropical sea surface temperature (SST) to global warming plays a crucial role in shaping both global and regional climates, so it receives immense attention and remains being debated. Here, we demonstrate that enhanced equatorial warming (EEW) is a more robust response to global warming than the commonly examined changes in the zonal SST gradient across the tropical Pacific, which is marked by discrepancies between observations and models. EEW is defined as the annual-mean SST warming averaged over 5°S-5°N, relative to the tropical SST warming averaged over 20°S-20°N. By combining observations and climate models, we identify the emergence of EEW in the Atlantic since the 1950s, primarily attributed to greenhouse gas forcing. The formation of EEW is driven by weakened equatorial upwelling, resulting from the slowdown of equatorial zonal winds. The identification of Atlantic EEW as a fingerprint of global warming has important implications for understanding changes in the tropical oceans in a warming climate and the associated impacts.