Ocean (De)oxygenation Across the Last Deglaciation: Insights for the Future

Jaccard, Samuel; Galbraith, Eric D.; Frölicher, Thomas L.; Gruber, Nicolas (2014). Ocean (De)oxygenation Across the Last Deglaciation: Insights for the Future. Oceanography, 27(1), pp. 26-35. Oceanography Society 10.5670/oceanog.2014.05

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Anthropogenic warming is expected to drive oxygen out of the ocean as the water temperature rises and the rate of exchange between subsurface waters and the atmosphere slows due to enhanced upper ocean density stratification. Observations from recent decades are tantalizingly consistent with this prediction, though these changes remain subtle in the face of natural variability. Earth system model projections unanimously predict a long-term decrease in the global ocean oxygen inventory, but show regional discrepancies, particularly in the most oxygen-depleted waters, owing to the complex interplay between oxygen supply pathways and oxygen consumption. The geological record provides an orthogonal perspective, showing how the oceanic oxygen content varied in response to prior episodes of climate change. These past changes were much slower than the current, anthropogenic change, but can help to appraise sensitivities, and point toward potentially dominant mechanisms of change. Consistent with the model projections, marine sediments recorded an overall expansion of low-oxygen waters in the upper ocean as it warmed at the end of the last ice age. This expansion was not linearly related with temperature, though, but reached a deoxygenation extreme midway through the warming. Meanwhile, the deep ocean became better oxygenated, opposite the general expectation. These observations require that significant changes in apparent oxygen utilization occurred, suggesting that they will also be important in the future.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)

UniBE Contributor:

Jaccard, Samuel

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

1042-8275

Publisher:

Oceanography Society

Language:

English

Submitter:

Monika Wälti-Stampfli

Date Deposited:

02 Oct 2014 10:17

Last Modified:

09 Dec 2014 17:45

Publisher DOI:

10.5670/oceanog.2014.05

BORIS DOI:

10.7892/boris.57910

URI:

https://boris.unibe.ch/id/eprint/57910

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