Climate Change Slows Earth's Rotation and May Affect Human Timekeeping

A new study by scientists has found that melting ice caps are slowing the Earth's rotation to the point where it is changing the way people measure time. For example, the next leap second, a mechanism used since 1972 to align official time with atomic clocks based on the Earth's unstable rotation rate, will be delayed by three years.  

According to a study published in the journal Nature, clocks may have to skip one second - the so-called "negative leap second" - until around 2029 to keep universal time in sync with the Earth's rotation. If not for the impact of melting ice, the time change would have been needed three years earlier, in 2026.

In recent decades, the Earth has been spinning faster due to changes in its core, but ice melting has prevented this speed surge and slowed the process.

Duncan Agnew, an author of the study and a geophysicist at the Scripps Institution of Oceanography at the University of California, says that melting ice in Greenland and Antarctica has changed the location of the Earth's core. And that's what has slowed the Earth's rotation, as less solid ice in the northern and southern parts of the planet means there is more mass around the equator, the study suggests.

To explain this, Agnew used the example of a figure skater spinning on ice. 

"If you have a skater who starts to spin, if she lowers her arms or extends her legs, she will slow down," he told NBC News.

However, if the skater's arms are pulled inwards, she will spin faster.

About 70 million years ago, days were shorter and lasted about 23.5 hours, according to a study in paleoceanography and paleoclimatology. This means that the dinosaurs of the Cretaceous period lived on a planet with 372 days in each year.  

As climate change intensifies, researchers expect ice melt to have an even stronger impact on the planet's rotation.