Projected ENSO teleconnection on the Southeast Asian climate under global warming

Abstract

Given the importance of El Niño–Southern oscillation (ENSO) teleconnection on the Southeast Asia (SEA) climate, the ENSO-induced precipitation and near-surface air temperature anomalies over SEA and its twenty sub-regions are compared between historical (1985–2014) and future (2070–2099) simulations using 30 models from Phase 6 of the Coupled Model Intercomparison Project (CMIP6). Future projections suggest that the Philippines, Malay Peninsula, most of the Maritime Continent, and southern Indochina experience reduced (increased) precipitation in the future El Niño (La Niña) summer. Then, during autumn, amplification of ENSO-precipitation teleconnection is projected in the Borneo, Malay Peninsula, and northern Vietnam, raising flood concerns in these sub-regions in future La Niña autumn. During winter, projected ENSO-driven negative anomalies continue intensifying and shifting northeastward, resulting in drier (wetter) conditions for the Philippines and surrounding areas in future El Niño (La Niña). Conversely, a southeastward shift of ENSO-driven precipitation anomalies is projected in the following spring, leading to dampening (an amplification) of teleconnection over the western (eastern) part of SEA. Regarding near-surface air temperature, a ‘land-sea contrast’ pattern is seen, in which intensified ENSO-driven positive (negative) anomalies are projected over land (ocean). At the sub-region scale, robust amplifications in the ENSO teleconnection are mainly observed when only considering the land temperature. The most noticeable future changes are robust amplification of the ENSO-driven positive temperature anomalies in northern Indochina and Myanmar during winter. These sub-regions typically experience a cooler winter, suggesting that wintertime mean temperature there may be much higher under future El Niño conditions. The projected changes in ENSO-driven precipitation and near-surface air temperature anomalies both appear to scale with the radiative forcing, i.e. a higher radiative forcing corresponds to higher teleconnection changes and more sub-regions of SEA experience robust changes. These results suggest that significant ENSO teleconnection changes can be mitigated by minimizing future warming.