Enhanced hydrological cycle increases ocean heat uptake and moderates transient climate sensitivity

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Authors

Maofeng Liu , Gabriel Vecchi, Brian Soden, Wenchang Yang , Bosong Zhang

Abstract

The large-scale moistening of the atmosphere in response to increasing greenhouse gases amplifies the existing patterns of precipitation minus evaporation (P-E) which, in turn, amplifies the spatial contrast in sea surface salinity (SSS). Through a series of CO2 doubling experiments, we demonstrate that surface salinification driven by the amplified dry conditions (P-E < 0), primarily in the subtropical ocean, accelerates ocean heat uptake. The salinification also drives the sequestration of upper-level heat into the deeper ocean, reducing the thermal stratification and increasing the heat uptake through a positive feedback. The change in Atlantic Meridional Overturning Circulation due to salinification plays a secondary role in heat uptake. Consistent with the heat uptake changes, the transient climate response would increase by approximately 0.4K without this process. Observed multi-decadal changes in subsurface temperature and salinity resembles those simulated, indicating that anthropogenically-forced changes in salinity are likely enhancing the ocean heat uptake.

DOI

https://doi.org/10.31223/X5H303

Subjects

Climate, Oceanography, Oceanography and Atmospheric Sciences and Meteorology

Keywords

Ocean heat uptake, Global hydrological cycle, Salinity, Transient climate sensitivity

Dates

Published: 2020-11-25 09:31

Last Updated: 2021-03-22 10:16

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License

CC BY Attribution 4.0 International

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