Climate snapshots trapped in ancient ice tell a surprising story

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18 March 2026 Climate snapshots trapped in ancient ice tell a surprising story Antarctic ice cores hint that changes in the ocean might have played a larger part than have greenhouse gases in key climate shifts of the past three million years. By Eric W. Wolff ORCID: http://orcid.org/0000-0002-5914-8531 0 Eric W. Wolff Eric W. Wolff is in the Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK. View author publications PubMed Google Scholar

Over the past three million years, global climate patterns have undergone two key temporal shifts. About 2.6 million years ago, ice sheets formed over the Northern Hemisphere at high latitudes, waxing and waning in 40,000-year cycles. Then, around one million years ago, during a time interval called the Mid-Pleistocene Transition (MPT) that cycle period increased to around 100,000 years, allowing ice sheets to grow larger. Now, two papers in Nature (Marks-Peterson et al.1 and Shackleton et al.2) explore the MPT using ice cores that have a highly disrupted structure, including non-chronological layering of ice that formed at different times.

Nature 651, 592-593 (2026)

doi: https://doi.org/10.1038/d41586-026-00636-3

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Competing Interests The author declares no competing interests.

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