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Antarctic Ice Cores Show Ocean Heat, Not CO2, Drove Ancient Climate Shifts
Ice core data reveal stable carbon dioxide and methane levels over 3 million years while ocean cooling likely drove major climate shifts during the Pliocene-Pleistocene transition.
- On Wednesday, March 18, 2026, Nature published two studies by Julia Marks-Peterson and Sarah Shackleton examining atmospheric CO2, methane levels, and ocean heat content over the past 3 million years.
- Researchers utilized an innovative ice analysis technique at the Allan Hills Blue Ice Area in Antarctica, extracting "Good data from bad ice" to analyze samples up to 4 million years old.
- The findings indicate broadly stable CO2 and CH4 levels across 3 million years, yet modern concentrations have risen far faster and to higher values than anything observed in these ancient records.
- Prof. Carrie Lear of Cardiff University said, "These papers don't rewrite the role of CO2," emphasizing the results show how sensitive the climate system is to small nudges.
- Rapid anthropogenic CO2 increases are pushing the planet toward unknown territory, warned Prof. Raymond Pierrehumbert FRS of the University of Oxford, as these changes risk crossing irreversible climate thresholds.
16 Articles
16 Articles
Coos Bay World
New ice core studies expand histories of greenhouse gases, ocean temperature
New analyses by Oregon State University and Princeton University researchers of ancient ice from Antarctica and the air contained inside it are extending the history of Earth’s climate records and expanding researchers’ understanding of how the planet has changed over…
Two studies published in "Nature", based on Antarctic ice analyses, reconstruct for the first time the evolution of greenhouse gas concentrations and ocean temperature over three million years, suggesting that mechanisms other than CO2 have played a role.
Global ocean heat content over the past 3 million years
The Pleistocene epoch was characterized by global cooling and an increase in the intensity and duration of glacial cycles. Regional surface and subsurface ocean temperature records follow distinct trends over this interval, suggesting dynamic changes in zonal and meridional heat transport and ocean circulation. These differing trends also complicate efforts to determine the evolution of total ocean heat content. Here we provide a record of mean …
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