Earth’s day is not always exactly 24 hours. It changes naturally because of the moon’s pull and processes inside the planet. But recent climate change adds a new factor. As ice melts, water moves from land to oceans, shifting Earth’s mass. This slows rotation, like a figure skater spinning more slowly when stretching their arms.
To study how unusual this is, researchers looked at tiny marine fossils called benthic foraminifera. The chemical makeup of these fossils shows old sea levels. Using this data and a special computer model, scientists could estimate how day length changed over millions of years.
During past ice ages, growing and melting ice sheets changed day length, but none as fast as today. Only around 2 million years ago was the change somewhat similar, but still slower.
This shows that today’s climate change is faster than anything in the last 3.6 million years, according to said Benedikt Soja of ETH Zurich. By the end of this century, human-driven climate change could affect day length even more than the moon does.
Even though the change is only a few milliseconds, it can affect precise tasks like space travel.
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