Abstract Time of emergence (ToE) – the time when climate change signals become distinguishable from natural variations – offers key insight into when climate impacts will become noticeable. Under the SSP585 scenario, ToE of strengthened El Niño–Southern Oscillation (ENSO) teleconnections to surface air temperature anomalies (TAS) over tropical rainforests and the Sahel transition zone (including northern South America, central and western Africa and Southeast Asia) in CMIP6 models appears notably earlier than other regions – as early as in the 2040s. ENSO-related precipitation anomalies in the deep tropics also emerge early in around the same period. These changing patterns are associated with a strengthened anomalous Walker Circulation in future ENSO and more robust ENSO TAS responses to global warming over the tropical rainforests/transition zone. It is found that Earth System models incorporating more comprehensive vegetation representation exhibit stronger responses in these areas and earlier ENSO TAS ToEs than models with limited vegetation feedbacks. This suggests that the early emergence of ENSO TAS teleconnections there can be attributed to atmosphere-land-vegetation feedbacks which amplify ENSO TAS responses. Our findings indicate that a strengthened relationship between ENSO and tropical rainforests and the Sahel transition zone could emerge in the coming decades.
LAI et al. (Tue,) studied this question.