Evidence for extreme export of Arctic sea ice leading the abrupt onset of the Little Ice Age

Martin W Miles; Camilla S Andresen; Christian V Dylmer

doi:10.1126/sciadv.aba4320

Evidence for extreme export of Arctic sea ice leading the abrupt onset of the Little Ice Age

Sci Adv. 2020 Sep 16;6(38):eaba4320. doi: 10.1126/sciadv.aba4320. Print 2020 Sep.

Authors

Martin W Miles^{1

2}, Camilla S Andresen³, Christian V Dylmer⁴

Affiliations

¹ NORCE Norwegian Research Centre, Bjerknes Centre for Climate Research, Bergen, Norway. martin.miles@norceresearch.no.
² Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80309, USA.
³ Geological Survey of Denmark and Greenland, Copenhagen, Denmark.
⁴ MMT Sweden AB, Västra Frölunda, Sweden.

Abstract

Arctic sea ice affects climate on seasonal to decadal time scales, and models suggest that sea ice is essential for longer anomalies such as the Little Ice Age. However, empirical evidence is fragmentary. Here, we reconstruct sea ice exported from the Arctic Ocean over the past 1400 years, using a spatial network of proxy records. We find robust evidence for extreme export of sea ice commencing abruptly around 1300 CE and terminating in the late 1300s. The exceptional magnitude and duration of this "Great Sea-Ice Anomaly" was previously unknown. The pulse of ice along East Greenland resulted in downstream increases in polar waters and ocean stratification, culminating ~1400 CE and sustained during subsequent centuries. While consistent with external forcing theories, the onset and development are notably similar to modeled spontaneous abrupt cooling enhanced by sea-ice feedbacks. These results provide evidence that marked climate changes may not require an external trigger.

Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).