Polar ice melting slows down the Earth’s rotation: what does it mean?

A new study has revealed an unexpected consequence of global warming: the day on our planet is getting longer due to the melting of the polar ice. Scientists from NASA and the Swiss Federal Institute of Technology Zurich (ETH Zurich) published their findings in the journal Proceedings of the National Academy of Sciences.

The researchers explain that the melting water from Greenland and Antarctica is redistributed around the equator. This phenomenon can be compared to a figure skater slowing down by spreading his arms. The Earth, although it appears to be round, is actually shaped like a «flattened spheroid» with a slight expansion at the equator.

Scientists have used a variety of techniques to measure changes in day length, including ultra-long-base radio interferometryUltra-long-base radio interferometry (VLBI) is an astronomical observational technique in which two or more radio telescopes located at great distances from each other synchronously record radio signals from space objects. and the Global Positioning System (GPS), which measures the Earth’s rotation very accurately, to about hundredths of a millisecond. They even analyzed ancient records of eclipses.

Now the main reason for the slowing of the Earth’s rotation is the gravitational influence of the Moon, which causes «tidal friction». However, the study predicts that by the end of the 21st century, the impact of climate change on day length will exceed the lunar effect if greenhouse gas emissions remain high.

From 1900 to today, climate change has lengthened the day by about 0.8 milliseconds. Under the worst-case scenario of high emissions, by 2100 the day could be 2.2 milliseconds longer compared to the beginning of the 20th century.

Although this change is imperceptible to humans, it is essential for space navigation. Accurately determining the Earth’s orientation is critical for communicating with spacecraft, such as the «Voyager» probes, which are now outside the solar system. At such vast distances, even a small deviation of a few centimeters at launch can lead to a discrepancy of kilometers at the target.

Source: Sciencealert