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Abstract

We examine the factors influencing the future of dissolved oxygen concentrations and future calcium carbonate (CaCO3) dissolution (CCD) rates. On the first topic, the importance of ocean oxygen to marine and terrestrial life is well-known, but ocean oxygen can be used for purposes other than breathing. Dissolved oxygen concentrations in the global ocean reflect changes in both physical and biogeochemical ocean processes. We present experiments that highlight the importance of remineralization in the oxygen budget and of ocean mixing in deoxygenation under a climate change scenario. We supplement these simulations with ones that make use of an adjoint-based general circulation ocean model. We show evidence that ocean oxygen provides information about ocean mixing. On the second topic, CaCO3 is known to dissolve throughout various portions of the water column, but little is known about how this will change in the future. Changes in ocean salinity, alkalinity, and mean age are most important in setting future CCD rates when a diagnostic approach is used. The most extreme future CCD rates are not uniformly determined by which future climate scenario is followed. However, on a global scale, results suggest that the ocean may buffer less against acidification if any of the geoengineering scenarios considered here are implemented than if our future emissions follow the most fossil fuel-intensive scenario.

Speaker information

Dr. David Trossman, by training, is a physical oceanographer but, by example, encourages earth system scientists to cross traditional disciplinary boundaries more often. David received his PhD at the University of Washington in Seattle in 2011 and eventually moved to Liverpool where he is now a Senior Research Scientist with the National Oceanography Centre. David uses numerical and statistical models as well as theory to improve existing or explore alternative observational methods to monitor basic ocean state variables, better understand ocean processes, and enhance ocean forecasting systems.

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