Climate response of the equatorial pacific to global warming

Pedro N. DiNezio, Amy C Clement, Gabriel A. Vecchi, Brian J Soden, Benjamin Kirtman, Sang Ki Lee

Research output: Contribution to journalArticle

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Abstract

The climate response of the equatorial Pacific to increased greenhouse gases is investigated using numerical experiments from 11 climate models participating in the Intergovernmental Panel on Climate Change's Fourth Assessment Report.Multimodelmean climate responses to CO2 doubling are identified and related to changes in the heat budget of the surface layer.Weaker ocean surface currents driven by a slowing down of the Walker circulation reduce ocean dynamical cooling throughout the equatorial Pacific. The combined anomalous ocean dynamical plus radiative heating from CO2 is balanced by different processes in the western and eastern basins: Cloud cover feedbacks and evaporation balance the heating over the warm pool, while increased cooling by ocean vertical heat transport balances the warming over the cold tongue. This increased cooling by vertical ocean heat transport arises from increased near-surface thermal stratification, despite a reduction in vertical velocity. The stratification response is found to be a permanent feature of the equilibrium climate potentially linked to both thermodynamical and dynamical changes within the equatorial Pacific. Briefly stated, ocean dynamical changes act to reduce (enhance) the net heating in the east (west). This explains why the models simulate enhanced equatorial warming, rather than El Niño-like warming, in response to a weaker Walker circulation. To conclude, the implications for detecting these signals in the modern observational record are discussed.

Original languageEnglish (US)
Pages (from-to)4873-4892
Number of pages20
JournalJournal of Climate
Volume22
Issue number18
DOIs
StatePublished - 2009

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global warming
climate
ocean
Walker circulation
warming
heating
cooling
stratification
warm pool
heat budget
Intergovernmental Panel on Climate Change
cloud cover
surface layer
sea surface
climate modeling
greenhouse gas
evaporation
basin
experiment

ASJC Scopus subject areas

  • Atmospheric Science

Cite this

Climate response of the equatorial pacific to global warming. / DiNezio, Pedro N.; Clement, Amy C; Vecchi, Gabriel A.; Soden, Brian J; Kirtman, Benjamin; Lee, Sang Ki.

In: Journal of Climate, Vol. 22, No. 18, 2009, p. 4873-4892.

Research output: Contribution to journalArticle

DiNezio, Pedro N. ; Clement, Amy C ; Vecchi, Gabriel A. ; Soden, Brian J ; Kirtman, Benjamin ; Lee, Sang Ki. / Climate response of the equatorial pacific to global warming. In: Journal of Climate. 2009 ; Vol. 22, No. 18. pp. 4873-4892.
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