How Earth's orbital wobble triggered rapid climate chaos 90 million years ago

Space · Published 22 October 2026 Swipe more like this →

In short: During the Late Cretaceous, the world was a greenhouse with no polar ice sheets and high CO2. Yet, scientists discovered that the climate still swung wildly between humid and arid states every few thousand years. The culprit wasn't melting ice, but a subtle cosmic dance known as axial precession.

For decades, a major mystery haunted paleoclimatology: how could rapid climate shifts occur in 'greenhouse' periods? During the last Ice Age, we know that temperatures in Greenland surged by up to 16°C within decades due to ice sheet dynamics. However, during the Late Cretaceous—roughly 90 million years ago—polar regions were free of ice sheets, leaving no massive glaciers to drive such abrupt changes.

A new study analyzing sediment cores from China's Songliao Basin reveals that Earth's axial precession—a slow wobble of its axis like a spinning top—is the likely driver. One full wobble takes approximately 26,000 years. Researchers found that these orbital cycles triggered repeating climate fluctuations every few thousand years, even when atmospheric CO2 levels were very high and the planet lacked significant ice cover.

This research, published in Nature Communications, highlights that Earth's climate system can reorganize much faster than slow orbital changes alone would suggest. Research into fossils from this epoch, including specimens dated between 86.3 and 83.6 million years ago during the Santonian Stage, helps researchers grasp how swift changes shaped land creature development and habitats throughout a highly varied biological era.

Current research led by Celina Suarez at the University of Arkansas is further exploring this era, specifically looking at how tectonic changes and climate interacted 90 million years ago. This period was marked by significant geological events, including the breakup of Pangea and rising sea levels that split North America into two distinct landmasses.

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