Deep Pacific Oxygenation and Atmospheric CO2 Over the Past 180 kyr
Abstract
The dominant signal in global climate over the late Pleistocene is the 100-kyr co-varying temperature and carbon dioxide variations observed in Antarctic ice cores. The temperature variations are likely modulated by the 100-kyr eccentricity signal and amplified by climate feedbacks which involve atmospheric CO2. The cause of atmospheric CO2 variability over late Pleistocene glacial-interglacial cycles is still debated. One prevalent hypothesis is that there is an increased storage of respired carbon in the deep ocean during glacial maxima. Ventilation of carbon stored in this reservoir is thought to play an important role in atmospheric CO2 increases associated with Pleistocene deglaciations. The presence of this respired carbon has been recorded by an array of paleoceanographic proxies from various locations across the global ocean.
Here we present a new, 180,000-year sediment core (MV1014-8JC, 6° 14.0' N, 86° 02.6' W; 1993 m water depth) from the Eastern Equatorial Pacific Ocean and reconstruct high-resolution 230Th derived fluxes of 232Th and barium, along with redox-sensitive uranium concentrations to examine past variations in dust delivery, export productivity, and bottom-water oxygenation, respectively, each of which may be directly- or indirectly-related to atmospheric CO2 levels. Our bottom-water oxygenation record is compared to similar high-resolution records from across the Pacific and in the Southern Ocean to infer global changes in bottom-water oxygenation over the past 180,000 years. We suggest that the North, Central Equatorial and Eastern Equatorial Pacific Ocean are important additional locations for deep-ocean respired carbon storage associated with periods of decreased global atmospheric CO2 concentrations.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMPP42A..03M
- Keywords:
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- 1626 Global climate models;
- GLOBAL CHANGE;
- 4902 Anthropogenic effects;
- PALEOCEANOGRAPHY;
- 4930 Greenhouse gases;
- PALEOCEANOGRAPHY;
- 4932 Ice cores;
- PALEOCEANOGRAPHY