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. 2018 Mar 12;9:1038. doi: 10.1038/s41467-018-03180-5

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© The Author(s) 2018

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

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Fig. 5 — Records of cryosphere and carbon cycle evolution over the past 70 Ma indicate near-sychronous initiation of Arctic sea ice, glaciation on Greenland, and Antarctic glaciation beginning in the middle Eocene (light blue horizontal bars; ~47–44 Ma). Prior to this time, proxy data support high and variable pCO₂, and there is no evidence for IRD. After this time, intermittent IRD appears indicating episodic glacials, synchronous with times of increasing δ¹⁸O. After ~34 Ma, corresponding to the Oi-1 benthic δ¹⁸O excursion, every sample at Site 913 examined in this study contains IRD sourced from Greenland, indicating more stable glacial conditions (dark blue horizontal bars). pCO₂ estimates indicate this event is followed by a reduction to the stable, low mean values that characterize the past ~30 million years. There is generally a correspondence of Fe oxide grain peaks, high δ¹⁸O, and low pCO₂. a IRD provenance data from this study for Site 913 indicates grains sourced from Greenland (green) and Arctic sources (blue line). Data for the ACEX core indicates Arctic sources³⁷. b Blue dotted line indicates times of sea ice in the Arctic Ocean, based on IRD provenance data from this study for Site 913 and record of Arctic sea ice diatoms and IRD in the ACEX core^{13,15–17,37} (ages calculated using one published age model⁶⁹). Underlying dotted blue line based on evidence for glacial ice on Greenland from this study and other IRD studies^{6–8,12,14,27,29}. Underlying dotted blue line indicates evidence for glacial ice on Antarctica from two or more proxies (e.g., studies of IRD, sequence stratigraphic record, and/or isotopic data)^{1,18,19,21,30,53–55,59}. Color of dashed blue horizontal line reflects inferred glacial frequency and intensity as inferred from proxies. c, d Compilation of benthic δ¹⁸O and δ¹³C data (5-point running mean) with notable isotopic excursions labeled. Intensity of blue horizontal line indicates glacial frequency and intensity as inferred from proxies. e Compilation of proxy atmospheric pCO₂ reconstructions (showing minimum and maximum estimates). Color of blue horizontal line reflects inferred glacial frequency and intensity as inferred from proxies. Complete list of data sources in Supplementary Methods