Climate Change is Lengthening Days at an Unprecedented Rate, Research Finds

New research suggests that human-driven climate change, through the melting of glaciers and ice sheets, is causing a redistribution of Earth's mass and slowing its rotation, resulting in longer days.

Current data indicates that days are lengthening by 1.33 milliseconds per century, a rate described as largely unparalleled over millions of years.

Research Uncovers the Impact

Geoscientists from the University of Vienna and ETH Zurich published these findings in a recent paper. Their study involved analyzing fossilized marine organisms called foraminifera and developing a deep-learning algorithm to assess sea-level fluctuations and calculate Earth's changing day length over nearly 4 million years.

According to Mostafa Kiani Shahvandi, a climate scientist and geophysicist at the University of Vienna, the chemical composition of foraminifera fossils allows inference of sea-level fluctuations, from which changes in day length can be mathematically derived.

The researchers also used a physics-informed diffusion model to support their results. This technique is designed to manage uncertainties inherent in paleoclimate data, capturing the physics of sea-level change while maintaining robustness against these uncertainties.

Mechanism and Historical Comparison

Previous work by the scientists described how melting global glaciers and polar ice sheets shift Earth's mass from the poles towards the equator. This shift alters the planet's oblateness, or its equatorial bulge.

The mass redistribution effect is comparable to an ice skater extending their arms to slow their rotation.

The new research specifically examined how the current day-lengthening effect compares to past periods. The analysis indicates that this effect has not been matched in eons, with exceptions occurring only during a few abrupt climate events characterized by rapid ice sheet growth or melting due to quick global cooling or warming.

Benedikt Soja, a professor of Space Geodesy at ETH Zurich and a co-author of the study, stated that the rapid increase in day length implies that the rate of modern climate change has been unprecedented since at least the late Pliocene, 3.6 million years ago. He attributes the current rapid rise in day length primarily to human influences.

Potential Implications

While 1.33 milliseconds may seem small, this change is considered sufficient to affect communications and space navigation technologies.

More pessimistic modeling suggests this trend could accelerate to approximately 2.62 milliseconds per century over the last few decades of the 21st century, potentially surpassing the Moon's influence on Earth's day length.

Shahvandi noted that only around 2 million years ago was a comparable rate of change in day length observed, but the current rate of planetary mass redistribution has been quicker in the period from 2000 to 2020.