Researchers from the University of Vienna and ETH Zurich have confirmed that climate-driven sea-level rise is lengthening Earth’s days by approximately 1.33 milliseconds per century. This acceleration, documented in a March 2026 study, represents a rate of rotational slowing not seen in the planet’s history for at least 3.6 million years.
The 1.33 Millisecond Shift
While the lengthening of a day may seem negligible, it represents a significant departure from historical norms. According to eciks.org, this rate of 1.33 milliseconds per century is an extreme outlier in planetary history. The research, published in the Journal of Geophysical Research: Solid Earth, suggests that human-induced climate change is now a primary driver of how our planet spins.
The study utilized a physics-informed deep-learning algorithm to analyze the chemical composition of fossilized benthic foraminifera—tiny marine organisms whose shells serve as biological archives for ancient sea levels. By reconstructing these sea-level fluctuations, researchers were able to calculate the corresponding changes in day length over the last several million years.
The data reveals a stark trend. Mostafa Kiani Shahvandi, the lead researcher, noted that the current pace of change is remarkably high compared to the geological record.
How Melting Ice Redistributes Planetary Mass
The mechanism behind this slowdown is a matter of classical physics: the redistribution of mass. As polar ice sheets and mountain glaciers melt, the resulting water migrates away from the poles and toward the equator, raising global sea levels. This shift moves a massive amount of weight farther from the Earth’s axis of rotation.
To visualize this, scientists often use the analogy of a figure skater. As news.google.com explains, when a skater extends their arms outward, their rotation slows; conversely, pulling the arms in causes them to spin faster. By moving water from the high latitudes to the equatorial oceans, climate change is effectively forcing the Earth to "extend its arms," decelerating its spin.
The scale of this movement is massive, yet the impact on time is microscopic. At the current climate-driven rate, it would take approximately 75,000 years for the day to lengthen by one full second. For any human observer, the change remains imperceptible, but for the machines and satellites that define modern life, the shift is measurable and consequential.
Reconciling Lunar Braking and Modern Climate Drivers
It is a common misconception that climate change is the sole cause of the Earth’s slowing rotation. For billions of years, the Moon has been acting as a natural brake through a process known as tidal braking. As Space Daily clarifies, this is not a "theft" of time but a transfer of angular momentum. The Moon’s gravitational pull on Earth’s tidal bulges creates a drag that slows our spin while simultaneously pushing the Moon into a wider orbit.
To understand the timeline, one must look past the popular narrative that days have steadily lengthened from 19 hours to 24. In reality, Earth once spun much faster—potentially in 10-hour increments—following the Moon’s formation 4.5 billion years ago. A 2023 study in Nature Geoscience found that the day actually held steady at roughly 19 hours for about a billion years during the mid-Proterozoic period. During that era, the slowing effect of lunar tides was nearly offset by atmospheric tides driven by solar heating.
Today, the balance is shifting. While lunar tidal braking remains a dominant long-term force, adding about 2.3 milliseconds of day length per century, the modern climate influence is rapidly catching up.
| Driver of Slowdown | Approx. Rate of Change | Primary Mechanism |
|---|---|---|
| Lunar Tidal Braking | 2.3 ms per century | Gravitational drag on ocean tides |
| Modern Climate Change | 1.33 ms per century | Mass redistribution via melting ice |
The High-Stakes Impact on Navigation and Timekeeping
While an extra millisecond won’t change a human’s schedule, it poses a significant challenge to the infrastructure of a high-tech civilization. Modern global systems rely on extreme temporal precision.
As The Weather Channel notes, the melting of glaciers is a direct contributor to this rotational deceleration. This has immediate implications for satellite-based services. Precise space navigation, GPS synchronization, and the operation of atomic clocks all depend on an incredibly accurate understanding of Earth’s rotation.
Even tiny errors in timing can accumulate, leading to measurable discrepancies in positioning data or synchronized communications. Benedikt Soja, a geophysicist at ETH Zurich, highlighted the technical stakes of these millisecond-scale shifts.
As we move toward the end of the 21st century, the influence of climate change on the length of our days is expected to grow. If sea-level rise continues to accelerate, the anthropogenic component of Earth’s rotational slowdown may eventually eclipse the long-standing influence of the Moon.
