Equatorial Pacific Warming Pattern Mitigated by Slow Ocean Adjustment

Editors’ Highlights are summaries of recent papers by AGU’s journal editors.

Source: AGU Advances

The Pacific sea-surface temperature (SST) gradient is the difference in SST across the tropical Pacific – typically warmer in the western Pacific and cooler in the eastern Pacific. It is a key control on tropical circulation, rainfall, and global climate sensitivity, making its accurate representation critical for reliable climate projections. Climate models project a decreased tropical Pacific SST gradient under global warming. In contrast, observations show the opposite with enhanced zonal SST gradients associated with cooling in the eastern tropical Pacific.

By running model simulations under an abrupt 4x CO₂ scenario, Olonscheck and Kang [2026] identify a two-phase transition in equatorial Pacific warming: an initial SST gradient strengthening followed by a long-term weakening. They find that the initial strengthening is caused by both equatorial forcing involving ocean circulation changes and remote Northern Hemisphere off-equatorial forcing involving atmospheric feedbacks. These fast responses transition to weakened gradients through slow ocean adjustments. These findings shed new light on oceanic feedback after global warming and support the improvement of future projections under climate change.

Citation: Olonscheck, D., & Kang, S. M. (2026). Phase transition of CO2-driven equatorial Pacific warming pattern governed by ocean dynamics and remote forcing. AGU Advances, 7, e2026AV002437. https://doi.org/10.1029/2026AV002437

—Alberto Montanari, Editor-in-Chief, AGU Advances

Text © 2026. The authors. CC BY-NC-ND 3.0
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