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Climate change isn’t just reshaping weather patterns, melting glaciers, and raising sea levels — it’s even altering the rotation of our planet. As global temperatures rise, polar ice melts and the resulting water redistributes itself across the oceans. This shift in mass causes Earth to spin slightly more slowly, making our days a little longer.
A new study reveals a striking detail: the current slowdown in Earth’s rotation is happening faster than at any time in the past 3.6 million years.
Researchers calculated in 2024 that a day is currently lengthening by about 1.33 milliseconds per century. The main drivers are melting ice sheets, shrinking glaciers, and rising sea levels. For comparison, during the 20th century this climate‑related effect was significantly smaller, ranging between 0.31 and 1.0 milliseconds per century.
To understand how unusual today’s changes are, an international research team — including scientists from the University of Vienna — looked millions of years into the past. They analyzed fossil shells of tiny marine organisms that are highly sensitive to environmental changes. Subtle chemical variations in these fossils reveal how sea levels shifted long ago.
From these sea‑level reconstructions, the scientists were able to infer how Earth’s rotation changed over time. The principle is similar to a figure skater performing a spin: when the skater extends their arms, they slow down. Likewise, when more water is distributed farther from Earth’s axis, the planet’s rotation decelerates.
Key finding
The study concludes that today’s rate of change is unprecedented in the last 3.6 million years. Only once — around two million years ago — was the effect similarly strong, and that was due to natural climate fluctuations. Today, human activity is the dominant cause.
If global warming continues, the long‑term impact of climate change could even surpass the influence of the Moon, which has been the primary factor slowing Earth’s rotation for billions of years.
- Hector Pascua/picture: pixabay.com
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