Precession and atmospheric CO 2 modulated variability of sea ice in the central Okhotsk Sea since 130,000 years ago

Lo, Li and Belt, Simon T. and Lattaud, Julie and Friedrich, Tobias and Zeeden, Christian and Schouten, Stefan and Smik, Lukas and Timmermann, Axel and Cabedo-Sanz, Patricia and Huang, Jyh-Jaan and Zhou, Liping and Ou, Tsong-Hua and Chang, Yuan-Pin and Wang, Liang-Chi and Chou, Yu-Min and Shen, Chuan-Chou and Chen, Min-Te and Wei, Kuo-Yen and Song, Sheng-Rong and Fang, Tien-Hsi and Gorbarenko, Sergey A. and Wang, Wei-Lung and Lee, Teh-Quei and Elderfield, Henry and Hodell, David A. (2018) Precession and atmospheric CO 2 modulated variability of sea ice in the central Okhotsk Sea since 130,000 years ago. Earth and Planetary Science Letters, 488. pp. 36-45. ISSN 0012821X DOI

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Recent reduction in high-latitude sea ice extent demonstrates that sea ice is highly sensitive to external and internal radiative forcings. In order to better understand sea ice system responses to external orbital forcing and internal oscillations on orbital timescales, here we reconstruct changes in sea ice extent and summer sea surface temperature (SSST) over the past 130,000 yrs in the central Okhotsk Sea. We applied novel organic geochemical proxies of sea ice (IP25), SSST () and open water marine productivity (a tri-unsaturated highly branched isoprenoid and biogenic opal) to marine sediment core MD01-2414 (53°11.77′N, 149°34.80′E, water depth 1123 m). To complement the proxy data, we also carried out transient Earth system model simulations and sensitivity tests to identify contributions of different climatic forcing factors. Our results show that the central Okhotsk Sea was ice-free during Marine Isotope Stage (MIS) 5e and the early-mid Holocene, but experienced variable sea ice cover during MIS 2–4, consistent with intervals of relatively high and low SSST, respectively. Our data also show that the sea ice extent was governed by precession-dominated insolation changes during intervals of atmospheric CO2 concentrations ranging from 190 to 260 ppm. However, the proxy record and the model simulation data show that the central Okhotsk Sea was near ice-free regardless of insolation forcing throughout the penultimate interglacial, and during the Holocene, when atmospheric CO2 was above ∼260 ppm. Past sea ice conditions in the central Okhotsk Sea were therefore strongly modulated by both orbital-driven insolation and CO2-induced radiative forcing during the past glacial/interglacial cycle.

Item Type: Article
Uncontrolled Keywords: 2018AREP; IA74
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Journal or Publication Title: Earth and Planetary Science Letters
Volume: 488
Page Range: pp. 36-45
Identification Number:
Depositing User: Sarah Humbert
Date Deposited: 02 May 2018 10:42
Last Modified: 02 May 2018 10:42

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