NOAA/WDS Paleoclimatology - St. Matthew Island, Alaska 5,500 Year Macrofossil and Oxygen Isotope Data

Anomalously low winter sea ice extent and early retreat in CE 2018 and 2019 challenge previous notions that winter sea ice in the Bering Sea has been stable over the instrumental record, although long-term records remain limited. Here, we use a record of peat cellulose oxygen isotopes from St. Matthew Island along with isotope-enabled general circulation model (IsoGSM) simulations to generate a 5500-year record of Bering Sea winter sea ice extent. Results show that over the last 5500 years, sea ice in the Bering Sea decreased in response to increasing winter insolation and atmospheric CO2, suggesting that the North Pacific is highly sensitive to small changes in radiative forcing. We find that CE 2018 sea ice conditions were the lowest of the last 5500 years, and results suggest that sea ice loss may lag changes in CO2 concentrations by several decades.

公元2018年与2019年出现的异常偏低冬季海冰范围与提早退冰现象，挑战了此前认为白令海冬季海冰在器测记录中保持稳定的认知，尽管长期器测记录仍较为有限。本研究利用取自圣马修岛（St. Matthew Island）的泥炭纤维素氧同位素记录，结合同位素耦合通用环流模式（isotope-enabled general circulation model, IsoGSM）模拟结果，重建了长达5500年的白令海冬季海冰范围序列。研究结果显示，在过去5500年间，白令海海冰范围随冬季太阳辐射与大气二氧化碳浓度升高而缩减，这表明北太平洋对辐射强迫的微小变化具有极高敏感性。本研究发现，公元2018年的海冰状况为过去5500年来的最低值，且结果表明海冰消融可能滞后于二氧化碳浓度变化数十年之久。