Trends in marine dissolved oxygen: Implications for ocean circulation changes and the carbon budget

Fortunat Joos, and Thomas F. Stocker, Climate and Environmental Physics, Physics Insitute, University of Bern, Bern, Switzerland

Gian-Kasper Plattner, Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California, USA

Arne Körtzinger, and Douglas. W. R. Wallace, Institute for Marine Research, University of Kiel, Germany

Recent measurements and model studies have consistently identified a decreasing trend in the concentration of dissolved O₂ in the ocean over the last several decades. This trend has important implications for our understanding of anthropogenic climate change. First, the observed oceanic oxygen changes may be a signal of the beginning of a re-organization of large-scale ocean circulation in response to anthropogenic radiative forcing. Second, the repartitioning of oxygen between the ocean and the atmosphere requires a revision of the current atmospheric carbon budget and the estimates of the terrestrial and oceanic carbon sinks as calculated by the Intergovernmental Panel on Climate Change (IPCC) from measurements of atmospheric O₂/N₂.