Decadal Trends in the Oceanic Storage of Anthropogenic Carbon from 1994 to 2014 [Oral]

EGU23-3463, updated on 29 Jan 2024 https://doi.org/10.5194/egusphere-egu23-3463 EGU General Assembly 2023 © Author(s) 2024. This work is distributed under the Creative Commons Attribution 4.0 License. Decadal Trends in the Oceanic Storage of Anthropogenic Carbon from 1994 to 2014 Jens Daniel Müller1, Nicolas Gruber1, Brendan Carter2,3, Richard Feely3, Masao Ishii4, Nico Lange5, Siv K Lauvset6, Akihiko Murata7, Are Olsen8, Fiz F Pérez9,10, Christopher Sabine11, Toste Tanhua5, Rik Wanninkhof12, and Donghe Zhu1 1ETH Zurich, IBP, U-SYS, Zurich, Switzerland ([email protected]) 2Cooperative Institute for Climate, Ocean, and Ecosystem Studies, University of Washington, Seattle, WA, 98105 3Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Seattle, WA, 98115 4Meteorological Research Institute, Japan Meteorological Agency, Tsukuba, Japan 5GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany 6NORCE Norwegian Research Centre, Bjerknes Centre for Climate Research, Bergen, Norway 7Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa, 237-0061, Japan 8Geophysical Institute, University of Bergen and Bjerknes Centre for Climate Research, Bergen, Norway 9Instituto de Investigaciones Marinas (IIM), CSIC, Vigo, Spain 10Oceans Department, Stanford University, Stanford, CA 94305, USA 11University of Hawaii at Manoa, Honolulu, HI, 96822 12Atlantic Oceanographic and Meteorological Laboratory, National Oceanographic and Atmospheric Administration, Miami, USA The oceanic sink for anthropogenic CO2(Cant) that humans have emitted into the atmosphere has been pivotal for limiting global warming. The transport of Cant from the surface into the ocean interior, where most of it is accumulating, is the rate limiting step for this uptake. Yet multi-decadal trends in the ocean interior storage of Cant have not been assessed at global scale. We determined such trends by applying the eMLR(C*) regression method to ocean interior observations collected between 1989 and 2020, and found that the global ocean storage of Cant grew by 29 ± 3 Pg C dec-1 and 27 ± 3 Pg C dec-1 (±1σ) from 1994 to 2004 and 2004 to 2014, respectively. Although the two growth rates are not significantly different, they imply a reduction of the oceanic uptake fraction of the anthropogenic emissions from 36 ± 4 % to 27 ± 3 % during the respective decades. We attribute this reduction to a decrease of the ocean buffer capacity and changes in ocean circulation. In the Atlantic Ocean, the maximum storage rate shifted from the Northern to the Southern Hemisphere, plausibly caused by a weaker formation rate of North Atlantic Deep Waters and an intensified ventilation of mode and intermediate waters in the Southern Hemisphere. Between 1994 and 2004, the oceanic Cant accumulation exceeded the net air-sea flux by 8 ± 4 Pg C dec-1, suggesting a loss of natural carbon from the ocean during this decade. Our results reveal a substantial vulnerability of the ocean carbon sink. Powered by TCPDF (www.tcpdf.org)