Amazon deforestation weakens Atlantic Niño variability

Abstract

The Amazon Basin has undergone rapid deforestation since the 1970s, causing biodiversity loss, regional climate shifts, and increased greenhouse gas emissions. Yet its impact on tropical ocean–atmosphere coupled variability remains unknown. Using observational datasets and targeted coupled general circulation model experiments, here we find that Amazon deforestation has contributed substantially (~23%) to the observed weakening of Atlantic Niño variability since 1970. Observational analyses and model experiments reveal that local warming and drying associated with deforestation enhance the interhemispheric thermal contrast over the tropical Atlantic. The enhanced thermal contrast strengthens surface cross-equatorial southerly winds, which in turn reduce the sensitivity of zonal wind stress to the zonal sea surface temperature gradient, weakening the Bjerknes feedback and Atlantic Niño variability. The combined observational and modeling results highlight a critical influence of land surface changes on the dynamics of the tropical coupled ocean–atmosphere system.