doi.org/10.1073/pnas.2424082123
Credibility: 989
#Antarctic
Millions of years ago, variations in the size of the Antarctic ice sheet directly influenced marine life in subtropical regions thousands of kilometers away
A new study reveals that a subtle astronomical cycle, related to the Earth’s tilt, played a surprising role in regulating biological productivity in the planet’s warmest oceans.
Researchers at the University of Wisconsin-Madison discovered that, around 34 million years ago, when the Antarctic ice sheet began to expand significantly, the so-called obliquity cycle-which lasts about 40,000 years and affects the Earth’s tilt angle-dominated changes in ocean circulation.
This cycle, which is stronger in polar regions, ultimately controlled the flow of nutrients reaching subtropical waters, fueling the growth of marine organisms.
Scientists reached this conclusion by analyzing sediment samples from the seabed, collected during ocean drilling expeditions between 2020 and 2022 aboard the research vessel JOIDES Resolution.
These sediments hold chemical traces that record ancient biological activity in the oceans.
Alexandra Villa, who participated in the expedition and is now a researcher in Germany, explains that today about three-quarters of marine productivity in regions north of 30 degrees south latitude depends on nutrients from the Southern Ocean, which surrounds Antarctica.
These nutrient-rich waters sink and then rise again at lower latitudes, fertilizing the sea surface.
When the Antarctic ice sheet grew large enough to reach the Southern Ocean, the 40,000-year rate of ice variations began to directly influence the distribution of these nutrients, altering the amount of life in the subtropical oceans.
Stephen Meyers, a professor of geosciences and one of the lead authors of the study, emphasizes that Earth’s climate system is extremely interconnected: changes in one polar region can propagate in unexpected ways, affecting distant food chains.
The article, published in the journal “Proceedings of the National Academy of Sciences,” reinforces the idea of “””global teleconnections”-climatic links that connect distant parts of the planet.
The researchers observe that, while other astronomical cycles tend to have a greater influence on regions near the Equator, during this specific period the obliquity cycle stood out clearly.
This discovery helps to better understand how the global climate functioned in the past and shows how small variations in the Earth’s tilt could reverberate throughout the planet, regulating life in the oceans through nutrient circulation.
The study highlights the surprising dynamics of the Earth system and the importance of the connections between polar ice, oceans, and marine life.
Published in 04/01/2026 00h51
Text adapted by AI (Grok) and translated via Google API in the English version. Images from public image libraries or credits in the caption. Information about DOI, author and institution can be found in the body of the article.
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