GSA Annual Meeting in Seattle, Washington, USA - 2017

Paper No. 271-6
Presentation Time: 9:00 AM-6:30 PM


GRAHAM, Grace M., FONTAINE, Alice and MEYER, Katja M., Department of Earth & Environmental Sciences, Willamette University, 900 State Street, Salem, OR 97301,

The end-Permian mass extinction coincided with a period of rapid climate warming, high atmospheric CO2 concentrations, and widespread ocean anoxia and euxinia. Ocean deoxygenation has previously been linked to greenhouse gas-driven changes in the carbon and nutrient cycles, but the extent to which temperature alone impacted ocean anoxia remains uncertain. Past studies have found that a rise in sea surface temperature will accelerate the metabolic activity of heterotrophic bacteria, which will increase the demand for oxygen and alter the depth at which it is consumed. Here, we used the cGENIE Earth system model of intermediate complexity with an end-Permian configuration to quantify the impact of warming on oceanic oxygen budget and distribution. We performed a series of simulations that incorporated a range of proposed atmospheric CO2 concentrations and varying configurations of the biological pump. In an abiotic ocean, increasing atmospheric CO2 reduces oxygen but does not lead to anoxia. Implementing a biological pump with a fixed remineralization profile causes a shallowing and expansion of the oxygen minimum zone (OMZ) with increased climate warming. In simulations that implement temperature-dependent remineralization in the biological pump, we observe similar OMZ changes but greater deep ocean anoxia. Overall, we find that the biological pump’s sensitivity to climate warming shoals the remineralization depth and enhances the expression of both shallow- and deep-water anoxia.