doi.org/10.1038/s41467-025-66219-4
Credibility: 589
#Climate Pulse
Scientists have discovered, in ancient sediments from China, a surprising climate cycle that repeated itself approximately every 5,000 years during the Cretaceous period, about 83 million years ago
At that time, Earth was in an extreme “greenhouse” state: the planet was much warmer than today, with high levels of carbon dioxide in the atmosphere (around 1,000 ppm) and virtually no polar ice caps.
Analyzing rock cores extracted from the Songliao Basin in northeastern China, researchers observed clear alternations between wet and dry periods that repeated regularly.
These changes followed a rhythm of 4,000 to 5,000 years, something unexpected in a world without large glaciers, since rapid climate oscillations are usually linked to the advance and retreat of ice.
The explanation lies in the slow oscillation of the Earth’s axis, called precession.
This movement, which completes a full cycle in about 26,000 years, alters how sunlight reaches tropical regions throughout the year.
In the Cretaceous period, this created a kind of quadruple “pulse” in tropical insolation: two intense peaks near the equinoxes and two minimums near the solstices.
This uneven distribution of solar energy directly influenced rainfall and drought patterns, generating cycles of humidity and aridity even without the presence of ice to amplify the changes.
The study shows that subtle variations in solar radiation, caused by astronomical factors, were capable of causing rapid and intense climatic oscillations on a hot planet.
Furthermore, the strength of these 5,000-year cycles varied over time, becoming more or less pronounced at rhythms linked to other orbital movements of the Earth, such as the eccentricity of the orbit (which changes approximately every 100,000 years).
This discovery is important because the Late Cretaceous can serve as a mirror for the future.
With current global warming bringing the planet to CO? levels similar to those of that time, understanding how the climate system behaved in a greenhouse world helps predict possible rapid variations.
Because Earth’s orbital configuration changes very slowly and will remain stable for billions of years, these high-frequency climate pulses could reappear on a warmer planet-and perhaps more predictably than we previously imagined.
Published in 03/16/2026 01h16
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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