A new study reported by the BBC reveals that Earth's days are gradually becoming longer as climate change causes polar ice and glaciers to melt, redistributing mass toward the equator and slowing the planet’s rotation. The change is extremely small—measured in fractions of milliseconds—but scientists describe the underlying force as immense and unmatched in millions of years. Researchers from the University of Vienna and ETH Zurich analyzed geological records to determine whether such rapid changes had occurred before.

The team examined fossilized shells of benthic foraminifera from the ocean floor, which preserve ancient sea-level data, and used a custom machine learning algorithm to refine records dating back 3.6 million years. They found that the current rate of lengthening, about 1.33 milliseconds per century, is unique in the geological record. The study attributes this to roughly 1,000 gigatons of mass shifting from polar regions to the oceans.

Scientists warn that if greenhouse gas emissions remain high, climate change could become the dominant factor affecting Earth's day length by the end of this century.