Earth’s Rotation Slowing: Climate Change Impact Confirmed | DW

The Earth’s rotation is slowing, a change imperceptible in daily life but measurable by scientists and increasingly linked to human-induced climate change. The deceleration, while slight – currently amounting to approximately 1.33 milliseconds per century – is considered unprecedented in recent geological history, rivaling a similar slowdown that occurred around two million years ago.

Researchers from Austria and Switzerland, publishing their findings in the journal Journal of Geophysical Research: Solid Earth, have established a connection between the increasing sea levels and the Earth’s diminished rotational speed. The study builds on previous work by Mostafa Kiani Shahvandi of the University of Vienna and Benedikt Soja of ETH Zurich, who demonstrated that melting polar ice and glaciers contribute to rising sea levels, which in turn exert a braking effect on the planet’s spin.

Kiani Shahvandi explained in a statement released by the University of Vienna that the phenomenon can be visualized using the analogy of a figure skater. “When a figure skater extends their arms, their spin slows down,” he said. The redistribution of mass, as water moves from the poles towards the equator, has a similar effect on the Earth’s rotation.

To understand the historical context of this slowdown, the researchers analyzed the chemical composition of marine fossils. These fossils served as indicators of past sea levels, allowing the team to model and calculate changes in the Earth’s rotational period over the past 3.6 million years. While the Earth’s rotation has varied throughout its history, the current rate of deceleration is comparable only to a period approximately two million years ago.

The study confirms that the current lengthening of the day is primarily attributable to human influence, specifically climate change. Soja stated to the German news agency dpa that the observed changes are “caused by climate change.” Calculations suggest that as global warming continues, the Earth’s rotation will continue to slow.

Though the changes in the Earth’s rotation are not felt directly in everyday life, they have implications for technologies that rely on precise timekeeping and navigation, such as global positioning systems and astronomical observations. The variations in the Earth’s rotation necessitate adjustments to Coordinated Universal Time (UTC) to maintain accuracy.

The Earth’s rotational period is not constant, naturally fluctuating due to the gravitational pull of the Moon and internal geophysical processes within the planet’s core, mantle, and atmosphere. However, the recent and accelerating impact of climate change is now recognized as a significant factor influencing the length of a day.