Work

The Impact of Underestimated Southern Ocean Freshening on Simulated Historical Sea Surface Temperature Trends

Year: 2025

Type: article

Abstract: Climate models generally overestimate observed Southern Ocean surface warming trends over the past three decades. This discrepancy could be due to biased surface freshwater fluxes in climate models, which underestimate observed precipitation increases and do not account for Antarctic Ice Sheet and shelf mass loss. Though past modeling experiments show surface cooling in response to freshwater perturbations, sea surface temperature (SST) responses vary widely across models. To address these ambiguities, we compute linear SST response functions for standardized freshwater flux increases across a subset of CMIP6 models. For 1990–2021, underestimated freshwater fluxes can explain up to 60% of the model‐observation SST trend difference. The response functions reveal that Southern Ocean SST trends are more sensitive to freshwater fluxes concentrated along the Antarctic margin versus more spatially distributed fluxes. Our results quantify, for the first time, the impact of missing freshwater forcing on Southern Ocean SST trends across a multi‐model ensemble.

Source: Geophysical Research Letters

DOI: 10.1029/2024gl112639

Authors: Zachary Kaufman, Earle Wilson, Ariaan Purich, Rebecca Beadling, Yuchen Li

Institutions: Stanford University, Monash University, Temple University

Language: English

Topic: Climate variability and models

Subfield: Global and Planetary Change

Field: Environmental Science

Domain: Physical Sciences

SDGs: Climate action, Life below water

Open Access status: gold

Estimated APC paid: $3,190