The melting of the polar ice caps is causing our planet to spin more slowly, increasing the length of days at an "unprecedented" rate. The paper shows that water flowing from the glaciers is creating mass around the equator, according to Surendra Adhikari, a co-author. It's like when a figure skater does a pirouette, first holding her arms close to her body and then stretching them out, said co-author Benedikt Soja. The initial fast rotation becomes slower due to the mass moving away from the axis. It's more accurate to call it an "oblate spheroid" that bulges around the equator than it is to call it a sphere. It's shape is constantly changing, from the impacts of the daily tides that affect the oceans and crusts to the longer term effects from drift of tectonic plates. The paper relied on observational techniques like Very Long Baseline Interferometry, where scientists can measure the difference in how long it takes for radio signals from space to reach different points on Earth. The Global positioning system, which measures Earth's rotation very precisely, was used to look at ancient eclipse records.
The length of day increases by a few milliseconds if the Earth turns more slowly. The gradual deceleration of 2.40 milliseconds per century can be attributed to the effects of the moon pulling on the oceans in a process called "tidal friction." The new study shows that a warming climate will be more significant than the Moon's pull by the end of the 21st century. Climate alone would make days 2.2 milliseconds longer by the year 2200, compared to the same baseline, if it were possible. It might not sound like much, but there are many implications for space and Earth navigation. Knowing the exact orientation of Earth at any given moment is crucial when trying to communicate with a spaceship, such as the Voyager probes that are now well beyond our Solar System, where even a slight deviation of a centimeter can end up being kilometers away. Agence France-Presse.