首页|Emergence of positive IOD-like warming pattern driven by greenhouse gases and anthropogenic aerosols during the recent four decades
Emergence of positive IOD-like warming pattern driven by greenhouse gases and anthropogenic aerosols during the recent four decades
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NETL
NSTL
Springer Nature
Abstract Most climate models project a positive Indian Ocean Dipole-like (pIOD-like) warming pattern in the tropical Indian Ocean (TIO), featuring stronger warming in the west than the east under global warming. However, it is still unclear whether this warming pattern has emerged in observations. Here, based on observational products, Coupled Model Intercomparison Project Phase 6 (CMIP6) experiments, including all forcing and single-forcing simulations, as well as Pacific and Atlantic pacemaker experiments, we found that the TIO features a pIOD-like warming pattern in observations during 1979–2020, confirmed by changes in atmospheric circulation and convection. External forcing makes a major contribution to the observed pIOD-like warming pattern, with greenhouse gases (GHGs) contributing the most through the weakening of Walker circulation. Anthropogenic aerosols also contribute to the pIOD-like pattern, mainly through the local ocean-atmosphere interaction driven by the increased aerosol emissions from South Asia. The CMIP6 inter-model uncertainty in the simulated pIOD-like warming pattern is related to the anomalous zonal winds over the TIO, not with the remote forcing from the Pacific Ocean, highlighting the importance of processes internal to the Indian Ocean. Before the satellite era (1920–1978), although GHG forcing favors the pIOD-like warming pattern but with weaker trend, the increased aerosol emissions from Europe and North America offset the contribution of GHGs via influencing the inter-hemispheric temperature contrast, resulting in an insignificant pIOD-like warming pattern under external forcing and in observations. This study highlights the importance of the combined effects of GHGs and anthropogenic aerosols in the recent emergence of pIOD-like warming pattern.
NETL
NSTL
Springer Nature
