MARCH 17, 2026
Stock image of the Earth rotating
Days are getting longer as a result of climate change, as warmer temperatures lead to a slowong pf Earth’s rotation at a rate scientists say has not been seen for at least 3.6 million years.
New research shows that rising sea levels caused by melting ice sheets are redistributing mass across the planet, reducing how fast Earth spins and gradually lengthening the day. Researchers found that days are currently increasing by about 1.33 milliseconds per century due to climate-related factors, a pace that stands out sharply in the planet’s recent geological history.
Earlier studies by the same team established that climate change affects sea levels and, as a result, Earth’s rotation—but the new work places the trend in a geological context.
“This rapid increase in day length implies that the rate of modern climate change has been unprecedented at least since the late Pliocene, 3.6 million years ago,” paper author and geodesist professor Benedikt Soja of ETH Zurich, Switzerland, said in a statement. “The current rapid rise in day length can thus be attributed primarily to human influences.
“By the end of the 21st century, climate change is expected to affect day length even more strongly than the Moon. Even though the changes are only milliseconds, they can cause problems in many areas, for example in precise space navigation, which requires accurate information on Earth’s rotation.”
Fellow paper author Mostafa Kiani Shahvandi of the University of Vienna explained added that the effect is similar to a figure skater spinning more slowly after extending their arms.
What remained uncertain, he said, was whether climate had ever lengthened the day this quickly before.
To answer that question, the team reconstructed changes in Earth’s day length going back millions of years.
To do this, the team relied on fossilized remains of benthic foraminifera, single-celled marine organisms that preserve chemical signals of past ocean conditions. By analyzing these fossils, scientists were able to infer historical sea-level fluctuations and calculate how those shifts would have affected Earth’s rotation.
The researchers then applied a type of deep learning algorithm to the findings, designed to reflect sea-level change while accounting for the uncertainty that comes with ancient climate data.
“From the chemical composition of the foraminifera fossils, we can infer sea-level fluctuations and then mathematically derive the corresponding changes in day length,” Kiani Shahvandi said. “This model captures the physics of sea-level change, while remaining robust to the large uncertainties inherent in paleoclimate data.”
The results show that Earth’s day length has varied significantly over the past 2.6 million years, particularly during the Quaternary period, when large continental ice sheets repeatedly grew and melted. Those ice-driven sea-level changes caused Earth’s rotation to speed up or slow down at different times.
But when compared with modern measurements, the researchers found that today’s increase in day length is exceptional. Only one period, around two million years ago, showed a rate of change that came close to present-day levels, and even that episode was slightly slower than what has been observed between 2000 and 2020.
“Never before or after that has the planetary ‘figure skater’ raised her arms and sea levels so quickly as in 2000 to 2020,” Shahvandi said.
The findings suggest that the current trend reflects a broader pattern of unusually rapid climate change.
Looking ahead, the researchers say climate change could have an even greater influence on Earth’s rotation. By the end of the 21st century, they estimate that climate-driven effects on day length may surpass the slowing impact caused by the Moon’s gravitational pull.
References
Kiani Shahvandi, M., Adhikari, S., Dumberry, M., Mishra, S., & Soja, B. (2024). The increasingly dominant role of climate change on length of day variations. Proceedings of the National Academy of Sciences, 121(30). https://doi.org/10.1073/pnas.2406930121
Kiani Shahvandi, M., & Soja, B. (2026). Climate-Induced Length of Day Variations Since the Late Pliocene. Journal of Geophysical Research: Solid Earth, 131(3). https://doi.org/10.1029/2025JB032161
Courtesy/Source: Newsweek
