Breaking News:Climate Change Is Slowing Earth’s Rotation, Day Lengthening Unprecedented In 3.6 Million Years– What Just Happened

Human-driven climate change alters Earth’s spin (Representational picture | Credit: NASA/ JPL Caltech)

Hyderabad: Earth’s rotation speed is not constant. Although only a minuscule fraction of a second, the gravitational effects of the Moon, as well as large-scale geophysical processes on the planet, affect how fast or slow the Earth rotates on its axis. In fact, climate change has been lengthening the days on Earth, primarily due to rising sea levels, which tend to slow the planet’s rotation. Now, researchers from the University of Vienna and ETH Zurich have found out that the current rate of day lengthening—1.33 milliseconds per century—has not been seen in the past 3.6 million years.

To come to this conclusion, the study, published in the Journal of Geophysical Research: Solid Earth, reconstructed ancient day-length fluctuations using the fossil remains of a single-celled marine organism, known as benthic foraminifera. “From the chemical composition of the foraminifera fossils, we can infer sea-level fluctuations and then mathematically derive the corresponding changes in day length,” says first author Mostafa Kiani Shahvandi from the University of Vienna.

The team also employed a probabilistic deep learning algorithm, a physics-informed diffusion model, to draw more robust conclusions. “This model captures the physics of sea-level change, while remaining robust to the large uncertainties inherent in paleoclimate data,” the scientists added.

The study found that during the Quaternary period (the last 2.6 million years), the repeated growth and melting of large continental ice sheets caused significant variations in day length through associated sea-level changes. When compared with values from the 21st century, however, it becomes evident that today’s increase in day length is exceptional within the climate history of the past 3.6 million years.

Notably, researchers noted that from 2000 to 2020, our days lengthened by a rate equivalent to 1.33 milliseconds per century due to climate-related factors. Explaining how rising sea levels caused by the melting of polar ice sheets and mountain glaciers slow down the rotation of the planet and expand the length of the day, Shahvandi compared it to the physics utilised by a figure skater who spins more slowly once they stretch their arms and more rapidly once they keep their hands close to their body. In the context of the planet, the water levels act as the hands.

Benedikt Soja, Professor of Space Geodesy at ETH Zurich, explained that the rapid increase in day length suggested the rate of modern climate change had been unprecedented at least since the late Pliocene, 3.6 million years ago. “The current rapid rise in day length can thus be attributed primarily to human influences,” Soja added.

By the end of the 21st century, climate change was expected to affect day length even more strongly than the Moon. Although the changes amounted to only milliseconds, Soja noted that they could still cause problems in many areas, such as precise space navigation, which requires accurate information on Earth’s rotation.