Most climate models project an enhanced mean sea surface temperature (SST) warming in the equatorial Pacific and Atlantic, and a zonal SST dipole in the Indian Ocean. The remote influences of these SST change patterns remain uncertain. To examine the extent to which the patterns of SST changes in the tropical Indian and Atlantic Oceans modulate the warming in the tropical Pacific Ocean, we compare nudging experiments with prescribed structured and uniform SST changes in the tropics outside the Pacific. We find that the warming patterns in the tropical Indian and Atlantic Oceans, respectively, drive a canonical La Niña‐like and elongated equatorial cooling through the Bjerknes feedback, acting to attenuate the warming in the equatorial Pacific substantially. The different SST cooling responses emanate from subtle differences between the initial wind forcing driven by the two basins' SST change patterns. These results have significant implications for future climate change projections.

The authors employ the Columbia Hazard model (CHAZ) to characterise future tropical cyclone (TC) activity under the shared socioeconomic pathways (SSP) SSP2-4.5, SSP3-7.0, and SSP5-8.5 by downscaling 12 models that participated in the Coupled Climate Model Intercomparison Project’s sixth generation (CMIP6), focusing on the Western North Pacific (WNP) and North Atlantic (ATL) basins. Results

Longitude-time evolution of sea surface temperature anomalies (SSTA) reveals a slow southeastward propagation from the western North Pacific (WNP) around 20°N to the Niño-3.4 region in the equatorial Central Pacific. The propagation is manifested as a narrow, southwest-northeast oriented SSTA band across the subtropical North Pacific, and its journey takes about 2–3 years. The propagating SSTA appears to engage the initiation of the El Niño–Southern Oscillation (ENSO). The anomalies of surface winds, sea level pressure, outgoing longwave radiation, and velocity potential all exhibit a concurrent and distinct eastward propagation, one that appears to be circumglobal and is coupled with the predominant 4–5 year frequency of the ENSO cycle. It is suggested that the previously found warming/cooling in the Indian Ocean induced by El Niño/La Niña, the progressive SSTA and wind anomalies across the Indian Ocean towards the WNP, and the predominant 4–5-year frequency of the North Pacific Oscillation collectively contribute to the reported SSTA propagation . The findings implicate that monitoring the SSTA propagation from the WNP towards the tropical central Pacific could be useful in tracking the ENSO development.

Dendrochronology in West Africa has not yet been developed despite encouraging reports suggesting the potential for long tree-ring reconstructions of hydroclimate in the tropics. This paper shows that even in the absence of local tree chronologies, it is possible to reconstruct the hydroclimate of a region using remote tree rings. We present the West Sub-Saharan Drought Atlas (WSDA), a new paleoclimatic reconstruction of West African hydroclimate based on tree-ring chronologies from the Mediterranean Region, made possible by the teleconnected climate relationship between the West African Monsoon and Mediterranean Sea surface temperatures. The WSDA is a one-half degree gridded reconstruction of summer Palmer Drought Severity indices from 1500 to 2018 CE, produced using ensemble point-by-point regression. Calibration and verification statistics of the WSDA indicate that it has significant skill over most of its domain. The three leading modes of hydroclimate variability in West Africa are accurately reproduced by the WSDA, demonstrating strong skill compared to regional instrumental precipitation and drought indices. The WSDA can be used to study the hydroclimate of West Africa outside the limit of the longest observed record and for integration and comparison with other proxy and archaeological data. It is also an essential first step toward developing and using local tree-ring chronologies to reconstruct West Africa’s hydroclimate.

The Walker circulation (WC) responds to CO₂ forcing at both short and long timescales. In climate models, the fast response accounts for a substantial portion of the total responses, but its mechanisms, particularly those pertaining to air‐sea interactions, remain unclear. We find contrasting fast WC responses in the first 2 years of abrupt CO₂ forcing, determined by the models' air‐sea coupling strength in the equatorial Pacific. In models with a strong coupling, wind anomalies induced by the instantaneous land‐sea thermal contrast trigger a Bjerknes feedback, leading to cooling in the equatorial Pacific and WC strengthening. The WC weakens gradually as the Bjerknes feedback wanes and the subsurface warm pool water migrates eastward as Kelvin waves. In models with a weaker coupling, the WC weakens monotonically. Our results suggest that the inter‐model discrepancy in WC changes is associated with the uncertainty in the fast component.