Antarctic Ice Cycles Influence Distant Ocean Productivity

Cycles in Antarctic ice sheet growth and decay shaped marine life thousands of miles away, study finds

Mar. 24, 2026 at 11:12am

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A new study led by researchers at the University of Wisconsin–Madison has found that cycles in the growth and decay of Antarctica's ice sheets once shaped marine biological productivity thousands of miles away in the subtropical ocean, about 34 million years ago. The researchers analyzed chemical signals preserved in ocean sediment to determine that the 40,000-year obliquity cycle, which is tied to changes in Earth's axial tilt, influenced ocean productivity in subtropical latitudes during the first expansion of the Antarctic ice sheet.

Why it matters

This finding is surprising because the 40,000-year obliquity cycle typically has a more limited influence on climate and ocean conditions near the equator, with other astronomical cycles expected to have a greater impact. The study shows how tightly connected Earth's climate system is, with changes in one part of the planet, like the polar ice sheets, able to ripple out and impact marine food webs far from the ice sheet.

The details

The researchers analyzed sediment cores collected during ocean drilling expeditions from 2020-2022 aboard the now-retired scientific drilling vessel JOIDES Resolution. The sediments contained chemical signals that recorded past biological productivity in the subtropical ocean. The team found a strong, singular influence of the 40,000-year obliquity cycle on ancient subtropical ocean bioproductivity, across a 1-million-year interval associated with the first expansion of the Antarctic ice sheets around 34 million years ago. This indicates that bioproductivity was being influenced by a distant high-latitude process, through nutrient delivery to the lower latitudes from the nutrient-filled Southern Ocean.

  • The study analyzed sediment cores collected during ocean drilling expeditions from 2020-2022.
  • The findings are associated with the first expansion of the Antarctic ice sheet around 34 million years ago.

The players

Stephen Meyers

A professor of geoscience at the University of Wisconsin–Madison and one of the study's lead authors.

Alexandra Villa

The co-lead researcher on the study, who was a PhD student at UW-Madison and a shipboard scientist on the drilling expedition. She is now a postdoctoral researcher at MARUM in Bremen, Germany.

JOIDES Resolution

The now-retired scientific drilling vessel that recovered the ocean sediment cores used in the study, funded by the US National Science Foundation and 23 collaborating countries.

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What they’re saying

“We generally expect other astronomical cycles to have a greater influence.”

— Stephen Meyers, Professor of geoscience at the University of Wisconsin–Madison

“This tells us that bioproductivity is being influenced by a distant high-latitude process, through nutrient delivery to the lower latitudes.”

— Stephen Meyers, Professor of geoscience at the University of Wisconsin–Madison

“Today, about three-quarters of all marine bioproductivity north of 30 degrees south of the equator is supported by nutrients derived from Southern Ocean circulation — this is the ocean that surrounds Antarctica.”

— Alexandra Villa, Postdoctoral researcher at MARUM in Bremen, Germany

“And when the ice sheet became large enough to extend to the Southern Ocean, the 40,000-year obliquity rhythm of the marine-based ice sheets impacted the delivery of nutrients to our subtropical site.”

— Alexandra Villa, Postdoctoral researcher at MARUM in Bremen, Germany

What’s next

The researchers plan to continue studying how changes in the Antarctic ice sheet over time have impacted ocean productivity and global climate patterns.

The takeaway

This study highlights the interconnectedness of Earth's climate system, showing how changes in one part of the planet, like the polar ice sheets, can have far-reaching effects on marine ecosystems thousands of miles away through global circulation patterns and nutrient delivery.