The Earth is slowing down: scientists have reported a record low in 3.6 million years
This is reported by Science Focus, citing research by a team from the University of Vienna and the Swiss Federal Institute of Technology Zurich.
Climate change affects not only temperature, glaciers and sea levels, but also the Earth’s rotation.
As the polar ice sheets and glaciers melt, water that was previously concentrated at high latitudes flows into the oceans and is redistributed closer to the equator.
This shifts mass away from the poles and gradually slows the planet’s rotation.
The length of a day has never been absolutely constant. The Earth’s rotation is influenced by the Moon’s gravitational pull, processes within the planet and changes in the atmosphere. But the current rate, according to the researchers, is exceptional even on a geological timescale.
What the study revealed
A team from the University of Vienna and the Swiss Federal Institute of Technology Zurich analysed how the Earth’s rotation has changed over millions of years.
To do this, the scientists used data on the fossilised remains of benthic foraminifera – single-celled marine organisms that lived on the seabed.
The chemical composition of their shells preserves information about past changes in sea level. Based on this data, researchers can assess how the Earth’s rotation has changed.
A special machine learning algorithm enabled conclusions to be drawn for the Late Pliocene period – approximately 3.6 million years ago.
According to the study’s findings, the current rate at which the length of the day is increasing is unprecedented over this entire time span.
How much is the day lengthening?
The current rate of the day’s lengthening, linked to climate change, is 1.33 milliseconds per century.
At first glance, this is a very small figure. But for planetary processes, it signifies a massive redistribution of mass.
Professor Benedikt Soda of the Swiss Federal Institute of Technology in Zurich explained that to achieve this effect, around 1,000 gigatonnes of mass would need to be shifted from the poles to the oceans.
To illustrate this, he described an ice cube 10 km high hovering over New York – taller than Everest.
Why this matters
Dr Mostafa Kiani Shahvandi of the University of Vienna noted that the change in the Earth’s rotational energy is equivalent to a magnitude 9.0 earthquake.
This is not about destruction, but about the scale of energy involved in the planetary process.
Although a millisecond seems insignificant, such changes are significant for high-precision synchronisation.
According to Soji, this is important for the operation of GPS navigation on Earth and the navigation of spacecraft in the Solar System.
When the day could become 25 hours long
Previously, scientists estimated that a 25-hour day on Earth could occur in about 200 million years.
These predictions are based on the assumption that the Earth-Moon system will continue to evolve in a similar direction.
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