Background pycnocline depth constrains future Ocean Heat Uptake Efficiency

Newsom, E., Zanna, L. and Gregory, J. ORCID: https://orcid.org/0000-0003-1296-8644 (2023) Background pycnocline depth constrains future Ocean Heat Uptake Efficiency. Geophysical Research Letters, 50 (22). e2023GL105673. ISSN 1944-8007 doi: 10.1029/2023GL105673

Abstract/Summary

The Ocean Heat Uptake Efficiency (OHUE) quantifies the ocean's ability to mitigate surface warming through deep heat sequestration. Despite its importance, the main controls on OHUE, and on its two-fold spread across contemporary climate models, remain unclear. We argue that OHUE is primarily controlled by mid-latitude ventilation strength in the background climate, itself related to pycnocline depth and stratification. This hypothesis is supported by a strong correlation between mid-latitude (30–60°) OHUE and the near-global average (60°S–60°N) pycnocline depth in CMIP5 and CMIP6 AOGCMs under RCP85/SSP585, and in a parameter perturbation ensemble of ocean GCM (MITgcm) experiments. This correlation explains about 70% of the CMIP5-6 spread in global OHUE. The relationship provides a pathway toward observationally constraining OHUE, and thus reducing uncertainty in projections of future global climate change and sea level rise.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/113868
Identification Number/DOI	10.1029/2023GL105673
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > NCAS
Publisher	American Geophysical Union
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