Nonlinearity of ocean heat uptake during warming and cooling in the FAMOUS climate model

Bouttes, N., Good, P., Gregory, J. M. ORCID: https://orcid.org/0000-0003-1296-8644 and Lowe, J. A. (2015) Nonlinearity of ocean heat uptake during warming and cooling in the FAMOUS climate model. Geophysical Research Letters, 42 (7). pp. 2409-2416. ISSN 0094-8276 doi: 10.1002/2014GL062807

Abstract/Summary

Atmospheric CO2 concentration is expected to continue rising in the coming decades, but natural or artificial processes may eventually reduce it. We show that, in the FAMOUS atmosphere-ocean general circulation model, the reduction of ocean heat content as radiative forcing decreases is greater than would be expected from a linear model simulation of the response to the applied forcings. We relate this effect to the behavior of the Atlantic meridional overturning circulation (AMOC): the ocean cools more efficiently with a strong AMOC. The AMOC weakens as CO2 rises, then strengthens as CO2 declines, but temporarily overshoots its original strength. This nonlinearity comes mainly from the accumulated advection of salt into the North Atlantic, which gives the system a longer memory. This implies that changes observed in response to different CO2 scenarios or from different initial states, such as from past changes, may not be a reliable basis for making projections.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/41301
Identification Number/DOI	10.1002/2014GL062807
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > NCAS
Publisher	American Geophysical Union
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