Evidence for ephemeral middle Eocene to early Oligocene Greenland glacial ice and pan-Arctic sea ice

• Published in: Nature Communications
• Main Authors: Tripati, Aradhna, Darby, Dennis
• Other Authors: Old Dominion University Norfolk (ODU), NSFNational Science Foundation (NSF) NSF-ARC 1107942, Department of Energy through BES grant DE-FG02-13ER16402, NSF through CAREER awardNational Science Foundation (NSF) EAR-1325054, "Laboratoire d'Excellence" LabexMER ANR-10-LABX-19, French government under the program "Investissements d'Avenir"French National Research Agency (ANR), ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: [SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology; Arctic; Greenland; Sea ice
• Online Access: https://hal.science/hal-02929073; https://doi.org/10.1038/s41467-018-03180-5

International audience Earth's modern climate is defined by the presence of ice at both poles, but that ice is now disappearing. Therefore understanding the origin and causes of polar ice stability is more critical than ever. Here we provide novel geochemical data that constrain past dynamics of glacial ice on Greenland and Arctic sea ice. Based on accurate source determinations of individual ice-rafted Fe-oxide grains, we find evidence for episodic glaciation of distinct source regions on Greenland as far-ranging as similar to 68 degrees N and similar to 80 degrees N synchronous with ice-rafting from circum-Arctic sources, beginning in the middle Eocene. Glacial intervals broadly coincide with reduced CO2, with a potential threshold for glacial ice stability near similar to 500 p.p.m.v. The middle Eocene represents the Cenozoic onset of a dynamic cryosphere, with ice in both hemispheres during transient glacials and substantial regional climate heterogeneity. A more stable cryosphere developed at the Eocene-Oligocene transition, and is now threatened by anthropogenic emissions.