Enhanced Arctic amplification began at the Mid-Brunhes Event 430,000 years ago

Scientific Reports
By: , and 

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Abstract

Arctic Ocean temperatures influence ecosystems, sea ice, species diversity, biogeochemical cycling, seafloor methane stability, deep-sea circulation, and CO2 cycling. Today's Arctic Ocean and surrounding regions are undergoing climatic changes often attributed to "Arctic amplification" - that is, amplified warming in Arctic regions due to sea-ice loss and other processes, relative to global mean temperature. However, the long-term evolution of Arctic amplification is poorly constrained due to lack of continuous sediment proxy records of Arctic Ocean temperature, sea ice cover and circulation. Here we present reconstructions of Arctic Ocean intermediate depth water (AIW) temperatures and sea-ice cover spanning the last ~ 1.5 million years (Ma) of orbitally-paced glacial/interglacial cycles (GIC). Using Mg/Ca paleothermometry of the ostracode Krithe and sea-ice planktic and benthic indicator species, we suggest that the Mid-Brunhes Event (MBE), a major climate transition ~ 400-350 ka, involved fundamental changes in AIW temperature and sea-ice variability. Enhanced Arctic amplification at the MBE suggests a major climate threshold was reached at ~ 400 ka involving Atlantic Meridional Overturning Circulation (AMOC), inflowing warm Atlantic Layer water, ice sheet, sea-ice and ice-shelf feedbacks, and sensitivity to higher post-MBE interglacial CO2 concentrations.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Enhanced Arctic amplification began at the Mid-Brunhes Event 430,000 years ago
Series title Scientific Reports
DOI 10.1038/s41598-017-13821-2
Volume 7
Year Published 2017
Language English
Publisher Springer
Contributing office(s) Eastern Geology and Paleoclimate Science Center
Description 14475; 6 p.
Other Geospatial Arctic Ocean