Earth's Rotation Slows 1.33 Milliseconds per Century, Fastest in 3.6 Million Years
Updated
Updated · BBC Science Focus · May 24
Earth's Rotation Slows 1.33 Milliseconds per Century, Fastest in 3.6 Million Years
2 articles · Updated · BBC Science Focus · May 24
A new study says climate-driven day lengthening has reached 1.33 milliseconds per century, making the current slowdown of Earth's rotation unmatched in the past 3.6 million years.
Melting polar ice sheets and glaciers are shifting roughly 1,000 gigatonnes of mass from high latitudes into oceans near the equator, slowing the planet like a skater extending their arms.
Researchers from the University of Vienna and ETH Zurich reconstructed ancient rotation changes from benthic foraminifera shells and used machine learning to test the geological record.
By 2100, under a high-emissions scenario, climate change could overtake the Moon as the biggest driver of day-length change, with implications for ultra-precise GPS and spacecraft navigation.
The team said the rotational shift reflects broader human-driven disruption—rising seas, extreme weather and other mass movements such as groundwater depletion that they are now studying.
Melting ice and changing atmosphere are slowing Earth. Which human-driven force will ultimately reshape our day?
How will a climate-forced 'negative leap second' impact our globally connected digital world?
Humans now rival the Moon's pull on Earth's spin. What other planetary systems are we fundamentally altering?
Human-Driven Climate Change Is Rapidly Slowing Earth's Spin: The Fastest Day-Lengthening in Geological History
Overview
Recent research confirms that Earth's rotation is slowing down at a notable rate as of May 2026. This slowdown is mainly caused by the redistribution of mass from the poles toward the planet's midsection, which changes Earth's angular momentum and results in longer days. While Earth's rotation has always varied, the current rate of deceleration stands out when compared to the past few million years. For example, about 2 million years ago, a similar increase in day length was linked to rising carbon dioxide levels and temperatures. Today, the ongoing changes highlight the significant impact of mass movement on Earth's rotation.