During the past century, the tropical Pacific Ocean has warmed significantly less than the other tropical oceans in response to increasing greenhouse gases (GHGs). This La Nina-like warming trend in the observations is in stark contrast to the El Nino-like warming trend projected by the Coupled Model Intercomparison Project (CMIP) models for both the 20th and 21st century. A recent study by Zhang et al. (2019) proposes a new mechanism to help explain how enhanced Indian Ocean warming during the past century has reduced the Pacific warming response. A commentary paper (Lee et al., 2020) published in Geophysical Research Letters reviews the proposed mechanism in a broader perspective and discusses large-scale atmospheric responses in the Indian, Pacific and Atlantic basins and their interactions to increasing GHGs. This commentary paper also discusses how the future weakening of the Atlantic Ocean circulation may influence the Pacific warming response, emphasizing the interactive response of the pantropical atmosphere-ocean to increasing GHGs.
Figure: This figure summarizes the La Nina-like warming trend in the Pacific and associated atmospheric circulation anomalies observed during the 20th century, and the El Nino-like warming trend and associated atmospheric circulation anomalies projected for the 21st century by CMIP models.
2019). Indian Ocean warming trend reduces Pacific warming response to anthropogenic greenhouse gases: An interbasin thermostat mechanism. Geophysical Research Letters, 46, 10882– 10890. https://doi.org/10.1029/2019GL084088. https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL084088., , , , , , & (
2020). Pantropical response to global warming and the emergence of a La Niña‐like mean state trend. Geophysical Research Letters, 47, e2019GL086497. https://doi.org/10.1029/2019GL086497. https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL086497., , , & (