The cycle, known as obliquity, reflects changes in the angle of Earth\u2019s axis and affects how solar radiation is distributed across latitudes over time.<\/p>\n
Researchers said the signal was notable because other astronomical cycles are generally expected to exert a stronger influence at lower latitudes.<\/p>\n
\u201cWe generally expect other astronomical cycles to have a greater influence,\u201d said Stephen Meyers, a professor of geoscience at the University of Wisconsin\u2013Madison and one of the study\u2019s lead authors.<\/p>\n
The signal appears during the Eocene\u2013Oligocene transition, a major climate shift about 34 million years ago, when Antarctica began developing a large continental ice sheet and Earth moved from greenhouse toward icehouse conditions.<\/p>\n
The authors link this orbital rhythm to Antarctic ice-sheet variability that influenced ocean circulation and nutrient delivery to subtropical waters, leaving a cyclic productivity signal in marine sediment records.<\/p>\n
They interpret this pattern as evidence that Antarctic ice-sheet variability altered Southern Ocean circulation, changing how nutrient-rich waters were delivered to lower latitudes. In this way, high-latitude climate changes were transmitted into subtropical marine environments.<\/p>\n
Marine sediment records show cyclic changes in subtropical bioproductivity that align with orbital forcing. The authors interpret this pattern as evidence that nutrient delivery to lower latitudes varied in phase with Antarctic ice-sheet fluctuations.<\/p>\n
The findings point to a teleconnection in which Antarctic ice-sheet dynamics influenced marine productivity thousands of kilometers away, showing that subtropical biological activity was linked to high-latitude climate change rather than local conditions alone.<\/p>\n
\u201cThe Earth System is so interconnected, and changes in one part of the planet can ripple out in surprising ways,\u201d Meyers said. \u201cThe polar ice sheets and global ocean circulation are important ways this manifests, impacting marine food webs far from the ice sheet. Our study shows how dynamic, variable and sometimes surprising, these \u2018global teleconnections\u2019 can be.\u201d<\/p>\n
The proposed mechanism involves changes in Southern Ocean circulation that affected how nutrients were delivered to lower-latitude surface waters. This provided a pathway through which Antarctic ice-sheet variability could influence subtropical marine bioproductivity.<\/p>\n
The results also suggest that early Antarctic ice-sheet development was tied to broader changes in ocean circulation during the Eocene\u2013Oligocene transition. The study provides evidence that orbital-scale variability at high latitudes influenced biological processes in distant marine regions under the climate conditions of that time.<\/p>\n
References:<\/p>\n
1 A. Villa, & S.R. Meyers, High-latitude teleconnections drive subtropical marine bioproductivity at the dawn of the Antarctic ice sheet, Proc. Natl. Acad. Sci. U.S.A. 123 (11) e2424082123, https:\/\/doi.org\/10.1073\/pnas.2424082123<\/a> (2026)<\/p>\n