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Earth’s rotation is slowing at an unprecedented rate of 1.33 milliseconds per century due to climate change, a finding that stands out starkly against 3.6 million years of planetary history. Researchers from the University of Vienna and ETH Zurich have confirmed that rising sea levels from melting polar ice sheets are redistributing mass across the planet, lengthening days and fundamentally altering Earth’s spin in ways not seen since the late Pliocene epoch.
Quick Facts
- Days lengthening by 1.33 milliseconds per century — the fastest rate in 3.6 million years
- Research published March 2026 in the Journal of Geophysical Research: Solid Earth
- Melting polar ice and glaciers are redistributing mass toward the equator
- By century’s end, climate change will outpace the moon’s influence on day length
How Climate Change Slows Earth’s Spin
When polar ice sheets and mountain glaciers melt, the resulting meltwater flows toward the equator and raises sea levels. This mass redistribution fundamentally changes how Earth rotates. The effect mirrors a figure skater: when a skater extends their arms, they spin more slowly; when they pull their arms in, they spin faster. Similarly, as water migrates from the poles toward the equator, Earth’s rotation decelerates.
Researchers at the University of Vienna and ETH Zurich reconstructed day-length changes over the past 3.6 million years by analyzing the chemical composition of fossilized benthic foraminifera—single-celled marine organisms whose shells preserve records of ancient sea levels. Using a physics-informed deep-learning algorithm, they calculated how sea-level fluctuations correspond to changes in day length. The results revealed that today’s rate of change is an extreme outlier in planetary history.
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Lead researcher Mostafa Kiani Shahvandi noted that only once before—around 2 million years ago—did day length increase at a nearly comparable rate. “Never before or after that has the planetary ‘figure skater’ raised her arms and sea levels so quickly as in 2000 to 2020,” he explained. This rapid acceleration underscores how dramatically human-driven climate change has altered fundamental planetary processes.
Implications for Timekeeping and Navigation
The slowdown has real consequences for technology and infrastructure. Precise timekeeping systems, satellite navigation, and space operations depend on accurate knowledge of Earth’s rotation. Even millisecond-scale changes can accumulate into measurable errors in systems relying on atomic clocks synchronized with Earth’s spin.
Benedikt Soja, a geophysicist at ETH Zurich, warned that by the end of the 21st century, climate change will exert more influence over day length than the moon does. “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,” he said. The finding suggests that climate adaptation must extend beyond traditional environmental concerns to encompass the technical infrastructure supporting modern civilization.
What This Reveals About Climate Change’s Scale
The unprecedented rate of day-length increase serves as a marker of climate change’s magnitude. The research demonstrates that human activity has altered Earth’s rotation in ways not seen for millions of years. The fact that this change is driven entirely by the melting of ice sheets and glaciers—processes directly linked to greenhouse gas emissions—connects planetary-scale physics to human industrial activity.
The findings suggest that climate change is not merely a weather or environmental problem; it is fundamentally reshaping how the planet itself operates. As ice continues to melt and sea levels rise, the slowdown will accelerate further. The study implies that unless emissions are reduced, Earth’s days will continue lengthening at rates that exceed natural variability by orders of magnitude, with cascading effects on systems that depend on precise temporal measurements.
Sources
- Phys.org — Study from University of Vienna and ETH Zurich on climate-induced day-length changes; detailed explanation of methodology using benthic foraminifera fossils
- Scientific American — Analysis of rising sea levels’ effect on Earth’s rotation and implications for timekeeping systems
- Newsweek — Report on research showing unprecedented rate of rotation change over 3.6 million years
- Live Science — Coverage of human-driven climate change slowing Earth’s rotation at rates not seen in millions of years
