A greater warming trend of sea surface temperature in the tropical Indian Ocean than in the tropical Pacific is a robust feature found in various observational data sets. Yet this interbasin warming contrast is not present in climate models. Here we investigate the impact of tropical Indian Ocean warming on the tropical Pacific response to anthropogenic greenhouse gas warming by analyzing results from coupled model pacemaker experiments. We find that warming in the Indian Ocean induces local negative sea level pressure anomalies, which extend to the western tropical Pacific, strengthening the zonal sea level pressure gradient and easterly trades in the tropical Pacific. The enhanced trade winds reduce sea surface temperature in the eastern tropical Pacific by increasing equatorial upwelling and evaporative cooling, which offset the greenhouse gas warming. This result suggests an interbasin thermostat mechanism, through which the Indian Ocean exerts its influence on the Pacific response to anthropogenic greenhouse gas warming.

The rapid Indian Ocean warming during the early‐21th century was a major heat sink for the recent global surface warming slowdown. Analysis of observational data and ocean model experiments reveals that during 2003–2012 more than half of the increased upper Indian Ocean heat content was concentrated in the southeast Indian Ocean (SEIO), causing a warming “hot spot” of 0.8–1.2 K decade⁻¹ near the west coast of Australia. This SEIO warming was primarily induced by the enhancements of the Pacific trade winds and Indonesian throughflow associated with the Interdecadal Pacific Oscillation's (IPO) transition to its negative phase, and to a lesser degree by local atmospheric forcing within the Indian Ocean. Large‐ensemble climate model simulations suggest that this warming event was likely also exacerbated by anthropogenic forcing and thus unprecedentedly strong as compared to previous IPO transition periods. Climate model projections suggest an increasing possibility of such strong decadal warming in future.

Atlantic Niño is the Atlantic equivalent of El Niño-Southern Oscillation (ENSO), and it has prominent impacts on regional and global climate. Existing studies suggest that the Atlantic Niño may arise from local atmosphere-ocean interaction and is sometimes triggered by the Atlantic Meridional Mode (AMM), with overall weak ENSO contribution. By analyzing observational datasets and performing numerical model experiments, here we show that the Atlantic Niño can be induced by the Indian Ocean Dipole (IOD). We find that the enhanced rainfall in the western tropical Indian Ocean during positive IOD weakens the easterly trade winds over the tropical Atlantic, causing warm anomalies in the central and eastern equatorial Atlantic basin and therefore triggering the Atlantic Niño. Our finding suggests that the cross-basin impact from the tropical Indian Ocean plays a more important role in affecting interannual climate variability than previously thought.

The Atlantic Niño is characterized by sea surface warming in the equatorial Atlantic, which can trigger La Niña, the cold phase of El Niño–Southern Oscillation (ENSO). Although observations show that the Atlantic Niño has weakened by approximately 30% since the 1970s, its remote influence on ENSO remains strong. Here, we show that this apparent discrepancy is due to the existence of two types of Atlantic Niño with distinct patterns and climatic impacts, which we refer to as the central and eastern Atlantic Niño. Our results show that with equal strength, the central Atlantic Niño has a stronger influence on tropical climate than its eastern counterpart. Meanwhile, the eastern Atlantic Niño has weakened by approximately 50% in recent decades, allowing the central Atlantic Niño to emerge and dominate the remote impact on ENSO. Given the distinct climatic impacts of the two types, it is necessary to distinguish between them and investigate their behaviors and influences on climate in future studies.

A downscaling approach is applied to future projection simulations from four CMIP5 global climate models to investigate the response of the tropical cyclone (TC) climatology over the North Pacific basin to global warming. Under the influence of the anthropogenic rise in greenhouse gases, TC-track density, power dissipation, and TC genesis exhibit robust increasing trends over the North Pacific, especially over the central subtropical Pacific region. The increase in North Pacific TCs is primarily manifested as increases in the intense and relatively weak TCs. Examination of storm duration also reveals that TCs over the North Pacific have longer lifetimes under global warming. Through a genesis potential index, the mechanistic contributions of various physical climate factors to the simulated change in TC genesis are explored. More frequent TC genesis under global warming is mostly attributable to the smaller vertical wind shear and greater potential intensity (primarily due to higher sea surface temperature). In contrast, the effect of the saturation deficit of the free troposphere tends to suppress TC genesis, and the change in large-scale vorticity plays a negligible role.