Scientists Say Climate Change Is Making Earth's Days Longer Than Before

A new study has found that Earth's days are gradually becoming longer as climate change melts polar ice sheets and glaciers. Scientists said the increase is extremely small and measured in fractions of a millisecond, but the forces behind it are massive and unlike anything seen in millions of years, reported BBC.

According to the study, the current rate at which Earth's rotation is slowing is now "unprecedented" in the past 3.6 million years of geological history.

Researchers explained that as glaciers and polar ice sheets melt due to climate change, water that was once stored near Earth's poles flows into the oceans and spreads toward the equator. This movement of mass away from the poles slows Earth's spin, similar to how a figure skater slows down by extending their arms while spinning.

Previous studies had already suggested that climate change was affecting Earth's rotation. Scientists from the University of Vienna and ETH Zurich then studied geological records to determine whether such rapid changes had occurred before. The researchers noted that Earth's rotation naturally changes over time because of several forces, including the Moon's gravity, movements deep inside the planet and shifts in the atmosphere.

These forces constantly affect the length of a day. However, scientists said climate change has now become powerful enough to compete with, and eventually surpass, these natural influences. To study changes over millions of years, researchers examined fossilised remains of tiny sea-floor organisms called benthic foraminifera.

The chemical composition of their shells preserved records of ancient sea-level changes. By analysing these shifts, scientists were able to estimate changes in Earth's rotation.

The team also used a specially designed machine learning algorithm to handle uncertainties in very old geological data. This helped researchers study records dating back to the Late Pliocene period around 3.6 million years ago. According to the study, today's rate of climate-driven day lengthening stands out from the entire geological record.

Scientists said the current rate of day lengthening is around 1.33 milliseconds per century. Although this may appear very small, researchers stressed that the amount of mass involved is enormous. Professor Benedikt Soja of ETH Zurich, who co-authored the study, said such a change required around 1,000 gigatonnes of mass moving from the poles into the oceans.

To help explain the scale, Soja said people could imagine a solid cube of ice placed over New York City that would rise 10 kilometres high, taller than Mount Everest.

Dr Mostafa Kiani Shahvandi of the University of Vienna, the study's lead author, said the change in Earth's rotational energy was comparable to the force of a magnitude 9.0 earthquake, not in terms of destruction but in terms of planetary-scale energy.

The study identified one similar period around two million years ago when the rate of change nearly matched today's levels.

Soja explained that the event happened because fragile ice sheets combined with a natural rise in carbon dioxide levels, leading to large-scale melting of polar ice sheets.

Researchers warned that under a future with high greenhouse gas emissions and continued dependence on fossil fuels, climate change could become the main driver of changes in Earth's day length by the end of the century.