Paleoceanographic Synthesis of Abrupt Sea Ice and Temperature Changes in the Subarctic Pacific and Marginal Seas through the Past 20,000 Years
Abstract
Substantial efforts have been concentrated over the last half-century on the paleoceaongraphy of the North Pacific. Here we synthesize existing paleoceanographic records of temperature and sea ice extent across the Subarctic Pacific and marginal seas, including the Bering Sea, Alaskan Gyre, and Sea of Okhotsk. We focus on 26 cores collected between 1988-2009 and from 36-60°N with well-developed chronologies to reconstruct the abrupt climate transitions of the last 20,000 years, including the abrupt warming events of the Northern Hemisphere glacial terminations (Termination IA, IB). Specifically, we utilize foraminiferal (δ18O & Mg/Ca) and coccolithophore (Uk'37) derived proxies for near-surface temperature reconstructions, and diatom assemblages and indicator species to reconstruct sea ice extent and marginal sea ice environments. Sea-ice associated diatom species peaked in compositional dominance mid-way through the deglaciation from the mid-Bølling ( 14.5 ka) to the early Allerød ( 13.8 ka). Even at the lowest latitude site (36°01.4'N, core MD01-2421), sea-ice affiliated diatoms peak in the Last Glacial Maximum ( 18 ka) and the early Bølling ( 13.8 ka). Biogeochemical proxies for late-spring to late-summer temperatures across the Subarctic Pacific indicate surface ocean warming between the Last Glacial Maximum ( 6°) and the Holocene (12-18°C) at all sites. However, region-specific, latitudinal differences in the timing and magnitude of warming and millennial scale deglacial oscillations are evident. For example, in the Western Subarctic Pacific the higher-latitude sites show lower amplitude warming through the deglaciation, but greater expression of ephemeral mid-Bølling cooling than lower latitude sites. Sea ice and temperature are important primary metrics for understanding the rate and magnitude of surface ocean response to abrupt warming events, including the response of subpolar environments to warming in the modern ocean.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.C31B0747D
- Keywords:
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- 0738 Ice;
- CRYOSPHEREDE: 1630 Impacts of global change;
- GLOBAL CHANGEDE: 4813 Ecological prediction;
- OCEANOGRAPHY: BIOLOGICAL AND CHEMICALDE: 4901 Abrupt/rapid climate change;
- PALEOCEANOGRAPHY