[OANNES Foro] Recent global-warming hiatus tied to equatorial Pacific surface cooling

[Mario Cabrejos]

Nature Volume: 501, Pages: 403-407
Date published: 19 September 2013
doi:10.1038/nature12534

Recent global-warming hiatus tied to equatorial Pacific surface cooling
Yu Kosaka1 & Shang-Ping Xie1, 2, 3 
1 Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive MC?206, La Jolla, California 92093-0206, USA 2 Physical Oceanography Laboratory and Ocean-Atmosphere Interaction and Climate Laboratory, Ocean University of China, 238 Songling Road, Qingdao 266100, China 3 International Pacific Research Center, SOEST, University of Hawaii at Manoa, 1680 East West Road, Honolulu, Hawaii 96822, USA

Summary
Despite the continued increase in atmospheric greenhouse gas concentrations, the annual-mean global temperature has not risen in the twenty-first century1, 2, challenging the prevailing view that anthropogenic forcing causes climate warming. Various mechanisms have been proposed for this hiatus in global warming3, 4, 5, 6, but their relative importance has not been quantified, hampering observational estimates of climate sensitivity. Here we show that accounting for recent cooling in the eastern equatorial Pacific reconciles climate simulations and observations. We present a novel method of uncovering mechanisms for global temperature change by prescribing, in addition to radiative forcing, the observed history of sea surface temperature over the central to eastern tropical Pacific in a climate model. Although the surface temperature prescription is limited to only 8.2% of the global surface, our model reproduces the annual-mean global temperature remarkably well with correlation coefficient r = 0.97 for 1970-2012 (which includes the current hiatus and a period of accelerated global warming). Moreover, our simulation captures major seasonal and regional characteristics of the hiatus, including the intensified Walker circulation, the winter cooling in northwestern North America and the prolonged drought in the southern USA. Our results show that the current hiatus is part of natural climate variability, tied specifically to a La-Niña-like decadal cooling. Although similar decadal hiatus events may occur in the future, the multi-decadal warming trend is very likely to continue with greenhouse gas increase.
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