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Strengthening of ocean heat uptake efficiency associated with the recent climate hiatus

Authors

Watanabe M., Kamae Y., Yoshimori M., Oka A., Sato M., Ishii M., Mochizuki T., Kimoto M.

Journal

Geophys. Res. Lett., 40, 3175-3179

DOI

10.1002/grl.50541

Abstract

The rate of increase of global-mean surface air temperature (SATg) has apparently slowed during the last decade. We investigated the extent to which state-of-the-art general circulation models (GCMs) can capture this hiatus period by using multimodel ensembles of historical climate simulations. While the SATg linear trend for the last decade is not captured by their ensemble means regardless of differences in model generation and external forcing, it is barely represented by an 11-member ensemble of a GCM, suggesting an internal origin of the hiatus associated with active heat uptake by the oceans. Besides, we found opposite changes in ocean heat uptake efficiency (k), weakening in models and strengthening in nature, which explain why the models tend to overestimate the SATg trend. The weakening of k commonly found in GCMs seems to be an inevitable response of the climate system to global warming, suggesting the recovery from hiatus in coming decades.