Unexpected decline in the ocean carbon sink under record-high sea surface temperatures in 2023
Year: 2025
Type: article
Abstract: In 2023, sea surface temperatures (SSTs) reached record highs, partly due to a strong El Niño. Based on historical responses to elevated global mean SSTs, oceanic CO 2 uptake in 2023 should have increased (−0.11 ± 0.04 PgC yr −1 ), driven by reduced outgassing in the tropical Pacific Ocean. However, using observation-based estimates of ocean CO 2 fugacity, we show here that the global non-polar ocean absorbed about 10% less CO 2 than expected (+0.17 ± 0.12 PgC yr −1 ). This weakening was caused by the anomalous outgassing of CO 2 in the subtropical and subpolar regions, especially in the Northern Hemisphere, driven primarily by elevated SSTs reducing the solubility of CO 2 . In most regions, this SST-induced outgassing was mitigated by the depletion of dissolved inorganic carbon in the surface mixed layer. Such negative feedbacks caused an overall muted response of the ocean carbon sink to the record-high SSTs, but this resilience may not persist under long-term warming or more severe SST extremes.
Source: Nature Climate Change
Institutions: ETH Zurich, Institute of Biogeochemistry and Pollutant Dynamics, University of East Anglia, Centre National de la Recherche Scientifique, Université de Versailles Saint-Quentin-en-Yvelines, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Université Paris-Saclay, CEA Paris-Saclay - Etablissement de Saclay, Laboratoire des Sciences du Climat et de l'Environnement, Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, University of Bremen, Flanders Marine Institute, Lamont-Doherty Earth Observatory, Columbia University
Language: English
Subfield: Oceanography
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $12,690
OpenAlex ID: W4413908421