Study Reveals Earth's Rotation Slowing Due to Climate Change
A recent study by scientists from the University of Vienna and ETH Zurich reveals climate change is beginning to affect Earth’s rotation due to melting polar ice caps. The redistribution of the planet’s mass is slowing its spin at a rate unseen in 3.6 million years.
The researchers found that the length of a day is now increasing by approximately 1.33 milliseconds per century. Although imperceptible in daily life, scientists say this change demonstrates the profound impact of human activity on the planet’s systems.
‘Human influence on Earth’s systems is now so profound that we are altering the planet’s rotation,’ said study co-author Professor Benedikt Soja, quoted by BBC Science Focus on Monday, 25 May 2026.
This phenomenon occurs as ice melts in Greenland, Antarctica, and other polar regions due to global warming. Meltwater flows into the oceans and spreads towards the equator, redistributing Earth’s mass.
This slowdown in rotation is akin to a figure skater extending their arms to slow their spin.
Previously, Earth’s rotation was known to be influenced by the Moon’s gravity, core dynamics, and atmospheric changes. However, recent research shows climate change is now one of the primary factors affecting the planet’s spin.
Researchers estimate that climate change’s impact on Earth’s rotation could surpass the Moon’s gravitational effects by the end of this century if greenhouse gas emissions continue to rise.
To reconstruct Earth’s rotational changes over millions of years, scientists used fossils of microscopic marine organisms called benthic foraminifera. The chemical composition of their shells preserves traces of ancient sea level changes.
This data was then analysed using machine learning algorithms to calculate changes in day length since the late Pliocene epoch, around 3.6 million years ago.
Of all periods studied, current conditions represent one of the most striking anomalies. According to Soja, such a change in day length requires a massive redistribution of mass.
‘This shift in day length requires redistributing approximately 1,000 gigatons of mass from the poles to the oceans. To visualise, it’s like placing an ice cube 10 kilometres high over New York City — taller than Mount Everest,’ he said.
Another researcher involved in the study, Mostafa Kiani Shahvandi, stated that the energy involved in the rotational change is equivalent to a magnitude 9 earthquake.
Researchers also identified a period around two million years ago when the rate of rotational change nearly matched today’s conditions. Back then, massive ice melt was triggered by natural carbon dioxide spikes and polar ice sheet instability.
However, they noted such natural occurrences are extremely rare. Today, human activity has produced similar effects in just over a century.
Beyond affecting Earth’s rotation, polar ice melt is linked to rising sea levels and more extreme weather. Researchers say even minor changes in day length remain critical for high-precision navigation systems like GPS and spacecraft navigation.