Oceanic oxygen in a warming climate: mechanisms, patterns, and timescales

Monday, 15 December 2014: 8:00 AM
Curtis A Deutsch1, Alexander van Geen2, William Berelson3, Takamitsu Ito4 and Thomas Weber1, (1)University of Washington Seattle Campus, School of Oceanography, Seattle, WA, United States, (2)Columbia University, Lamont-Doherty Earth Observatory, Palisades, NY, United States, (3)University of Southern California, Los Angeles, CA, United States, (4)Georgia Institute of Technolog, Atlanta, GA, United States
The oxygenation of the ocean reflects a balance of physical O2 supply and biological O2 demand, both of which are strongly influenced by climate. The processes governing changes in O2 supply and demand are spatially heterogeneous and involve multiple time scales, leading to complex pattern of O2 variability. We present an analysis of model simulations, historical observations, and the recent sedimentary record that reveal fundamental differences between the O2 response of the tropics and high latitudes to rising greenhouse gases. Whereas the reduction in O2 solubility and a slowing of ocean circulation act in concert to deoxygenate the mid- and high-latitudes, these processes tend to counteract one another in the tropics. Emerging evidence from the sedimentary record and model reconstructions in the Pacific Ocean indicates that oxygen demand is the dominant control on oxygenation in the eastern tropical anoxic zones on decadal to centennial time scales. This reduction is closely linked to the strength of the tropical trade winds and upwelling, providing a mechanism for transient contraction of anoxia during climate warming.