Indian Ocean Warming Trend Reduces Pacific Warming Response to Anthropogenic Greenhouse Gases: An Interbasin Thermostat Mechanism

TitleIndian Ocean Warming Trend Reduces Pacific Warming Response to Anthropogenic Greenhouse Gases: An Interbasin Thermostat Mechanism
Publication TypeJournal Article
Year of Publication2019
JournalGeophysical Research Letters
Date Published09/2019
Abstract / Summary

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.

URLhttp://dx.doi.org/10.1029/2019gl084088
DOI10.1029/2019gl084088
Journal: Geophysical Research Letters
Year of Publication: 2019
Date Published: 09/2019

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.

DOI: 10.1029/2019gl084088
Citation:
Zhang, L, W Han, K Karnauskas, G Meehl, A Hu, N Rosenbloom, and T Shinoda.  2019.  "Indian Ocean Warming Trend Reduces Pacific Warming Response to Anthropogenic Greenhouse Gases: An Interbasin Thermostat Mechanism."  Geophysical Research Letters.  https://doi.org/10.1029/2019gl084088.