Melting polar ice caps causing Earth’s rotation to slow, new study finds
As the climate crisis continues to escalate, new research reveals that the melting of polar ice caps is causing the Earth to spin more slowly, extending the length of days at an unprecedented rate.
Study highlights changes in Earth’s rotation
The study, published in the Proceedings of the National Academy of Sciences, explains how water flowing from Greenland and Antarctica adds more mass around the equator. This shift is analogous to a figure skater slowing down their spin by extending their arms, according to co-author Benedikt Soja of ETH Zurich.
“The initially fast rotation becomes slower because the masses move away from the axis of rotation, increasing physical inertia,” Soja elaborated.
Earth’s changing shape
Though Earth is often described as a sphere, it is more accurately an “oblate spheroid,” bulging around the equator and resembling a satsuma. This shape is constantly changing due to the impacts of daily tides, tectonic plate drift, and abrupt shifts caused by earthquakes and volcanoes.
The study utilized advanced observational techniques, including Very Long Baseline Interferometry and the Global Positioning System, to measure Earth’s rotation with extreme precision. Historical eclipse records spanning millennia were also examined.
“If humans continue to emit greenhouse gases at a high rate, the effect of a warming climate will be greater than that of the Moon’s pull by the end of the 21st century,” said co-author Surendra Adhikari of NASA’s Jet Propulsion Laboratory.
Currently, the Moon’s gravitational pull causes a deceleration of 2.40 milliseconds per century through “tidal friction.”
Impact of climate change on day length
From 1900 to the present, climate change has already caused days to lengthen by about 0.8 milliseconds. Under the worst-case scenario of high emissions, climate alone could extend days by 2.2 milliseconds by 2100, compared to the baseline.
While this increase might not be perceptible to humans, “it holds significant implications for space and Earth navigation,” said Adhikari.
Importance for space navigation
Knowing exactly where the Earth is pointing in space is crucial for communication with distant spacecraft like Voyager. Even a tiny mistake of just a centimeter can result in being kilometers off-target by the time the signal reaches the spacecraft.
