Observations-constrained projections reveal early and strong deoxygenation in the interior North Atlantic
Abstract
Interior ocean deoxygenation is projected in response to climate change, yet the mechanisms remain poorly constrained, particularly at regional scale. Using an extensive oxygen data compilation complimented with a hindcast biogeochemical general circulation model simulation, we show a considerable temporal variability in the interior subpolar North Atlantic oxygen. Over multidecadal timescale, this variation is shown to significantly covary with the strength of the subpolar gyre, which coincides with the winter ventilation intensity in the Labrador Sea. During an anomalously strong gyre strength, the interior water mass properties are characterized by colder and younger seawater, leading to an anomalously high oxygen content, and vice versa during weak gyre strength periods. Most CMIP5 models do not reproduce this observed mechanism, and those that properly do, agree in projecting deoxygenation of -8% by 2100, more than double the global estimates. Steady weakening of the subpolar gyre strength and Labrador Sea stratification were identified as the main long-term drivers. The time of emergence of the deoxygenation signal in this region is projected to be earlier than temperature and salinity signals, suggesting that oxygen in this region in more sensitive to anthropogenic-induced circulation changes.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMOS32D..03T
- Keywords:
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- 4805 Biogeochemical cycles;
- processes;
- and modeling;
- OCEANOGRAPHY: BIOLOGICAL AND CHEMICALDE: 4806 Carbon cycling;
- OCEANOGRAPHY: BIOLOGICAL AND CHEMICALDE: 4813 Ecological prediction;
- OCEANOGRAPHY: BIOLOGICAL AND CHEMICALDE: 4815 Ecosystems;
- structure;
- dynamics;
- and modeling;
- OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL