When a viewer watches the day after tomorrowthey saw a hypothetical version of a sudden and dramatic climate collapse. Although the speed of these events was exaggerated in the movies, scientists know that Earth’s climate can indeed change suddenly. During the last ice age, temperatures in Greenland rose by 16 degrees Celsius in just a few decades. Huge waves of icebergs repeatedly disrupted circulation in the North Atlantic during events known as the Dansgaard-Eschger and Heinrich phenomena.
These kinds of rapid changes, called millennium-scale climate events, reveal that Earth’s climate system can reorganize much faster than would be expected from slow changes in Earth’s orbit alone.
Researchers have long believed that such rapid climate change is primarily related to the growth and collapse of large ice sheets. It left a big mystery unsolved. How could similar rapid climate change occur during greenhouse periods in Earth’s history when there were few ice sheets?
A new international study may provide the answer.
Scientists link orbital wobble to rapid climate change
A research team led by Professor Chengshan Wang of the China University of Geosciences in Beijing, in collaboration with scientists from Belgium, Austria and China, has found evidence that slow changes in the Earth’s orbit could have caused rapid climate change even in ice-free greenhouse climates. Their discovery is nature communications.
The researchers analyzed a sediment core from China’s Songliao Basin, which was deposited during the Late Cretaceous period, about 83 million years ago. At the time, the Earth was in a greenhouse state with extremely high levels of carbon dioxide in the atmosphere and virtually no polar ice sheets.
The sediment cores were obtained from the Cretaceous Continental Scientific Drilling Project, an international drilling effort started by Professor Wang in 2006.
Effects of Earth’s precession on climate
The Earth does not rotate in a perfectly stable manner. Its axis slowly wobbles over time, like a spinning top. This is known as axial precession. One complete wobble takes about 26,000 years.
This wobble interacts with gradual changes in Earth’s elliptical orbit to produce two major climate precession cycles lasting approximately 19,000 and 23,000 years. These cycles influence how sunlight is distributed between the Northern and Southern Hemispheres during each season and are important drivers of long-term climate patterns.
This effect is particularly important in tropical regions. Because the Earth’s axis is tilted relative to its orbit, solar radiation peaks once a year near the summer solstice in regions other than the tropics. It behaves differently in tropical regions. There are two annual peaks in solar radiation around the spring equinoxes and two annual minimums around the summer solstice.
This unique tropical sunlight pattern creates four peaks in solar contrast each season. Over time, this pattern produces a quarter precession cycle that lasts about 5,000 years.
Evidence of the age of dinosaurs
The research team found strong evidence for these cycles in the ancient sedimentary record.
Using geochemical data, mineral analysis, and bioturbation simulations, the researchers found that the Late Cretaceous experienced repeated wet and dry climate cycles. These changes occurred in a regular rhythm over approximately 4,000 to 5,000 years. The strength of these oscillations also varied with the longer 100,000-year orbital period, which is related to changes in Earth’s orbital eccentricity.
The results were broadly consistent with theoretical predictions about how tropical solar radiation responds to the shape of Earth’s orbit.
The researchers say this shows that changes in equatorial sunlight alone can cause large climate changes. Their spectral analysis also suggested that these 5,000-year cycles could trigger even faster climate oscillations lasting 1,800 to 4,000 years through nonlinear climate interactions.
Taken together, this evidence suggests that Earth’s climate was far from stable during the Late Cretaceous greenhouse world. Instead, it moved repeatedly between wet and dry conditions under the influence of orbital forces associated with precession.
What this means for the future of the planet
“During the Late Cretaceous, atmospheric carbon dioxide concentrations reached around 1,000 parts per million, which is comparable to expectations for the end of this century,” says Professor Michael Wagleich, a paleoclimatologist at the University of Vienna. “This makes the Cretaceous greenhouse climate a meaningful analog for understanding Earth’s future.”
“As the Earth’s orbital configuration remains stable for billions of years, the close link between astronomical precession and millennium-scale climate cycles that we uncover suggests that high-frequency climate fluctuations like those seen during the Cretaceous may occur in a warmer future, potentially in a more predictable manner than previously thought,” concluded Zhifeng Zhang, lead author of the study.
This research was funded by the Deep Earth Exploration and Mineral Resources Exploration-China National Science and Technology Key Project (No. 2024ZD1001105), the National Natural Science Foundation of China (No. 42272134 to YH, 42488201 to CW, 42502020 to CW, 42172137 to CM), and the National Key Research and Development Program of China. (No. 2023YFF0804000 to CM), China University of Geosciences (Beijing) Deep Time Digital Earth Frontier Science Center “Deep Time Digital Earth” Science and Technology Leading Talent Team Fund for Central Universities (Basic Research Funds for Central Universities) (No. 2652023001 to CW), and Postdoctoral Fellowship Program CPSF (No. GZC20241605 to ZZ). QY is a senior investigator at the FNRS Foundation for Scientific Research (FRS-FNRS) and acknowledges support from FRS-FNRS grant number T.0246.23. ZZ gratefully acknowledges the fellowship from China Postdoctoral Science Foundation (No. 2025M770431). ACDS thanks FNRS for support WarmAnoxia (grant T.0037.22).
