Universal time measurement is threatened by climate change!

Since 1967, Coordinated Universal Time (UTC) has been calculated from measurements of ultra-stable atomic clocks that determine time around the world and enable infrastructure digitaldigital and communications tools such as satellite navigation to operate with extreme precision.

Did you know ? Global warming was first mentioned in… 1856! Find out the story of the woman who demonstrated this in Science Hunters. © Futura

For historical reasons, UTC time remains tied to astronomical time, calculated using rotational speedrotational speed Earth that is not permanent. Therefore, in 1972, it was decided to add an extra second to atomic time so that it coincides with astronomical time. This addition occurs irregularly whenever the difference between the two standards approaches 0.9 seconds. The latest of these dates back to 2016, Duncan Agnew, author of the study published in the AFP journal, tells AFP. Nature.

But the acceleration of the Earth’s rotation means that astronomical time will gradually exceed atomic time. Which might make us, in a few years, imagine a second… negative. A leap into the unknown that metrologists and time scientists fear, given the challenges “unprecedented” what could this cause “in an increasingly interconnected world”emphasizes Patricia Tavella from the International Bureau of Weights and Measures (BIPM) in a commentary accompanying the study. “I wouldn’t recommend being on a plane at this time.”, supported by Demetrios Matsakis, former chief scientist at the US Naval Observatory, who was not involved in the work. Because computer programs that integrate leap seconds “Let’s assume they are all positive”– explains Duncan Agnew from the Institute of Geophysics at the University of California, San Diego.

Earth slows down due to melting ice

Partly for this reason, metrologists around the world have agreed to eliminate the leap second by 2035. Starting this year, it is planned to leave the difference between atomic time and the Earth’s rotation increasing to up to a minute. But what to do in the meantime?

According to the study Nature, global warmingglobal warming may shake up the program. Questionable: the acceleration of ice melting in Greenland and AntarcticAntarctic, which the researcher was able to measure thanks to satellite observations. Since the 1990s, melting ice has slowed the Earth’s rotation, as have tidal influences from the Moon and Earth. SunSunbalancing natural acceleration. “When the ice melts, the water spreads throughout the ocean. […] What changes the distribution of liquids on the surface and inside the Earth »– explains the scientist.

Nothing new yet: the slowing effect of ice melting has been speculated since the end of the 19th century.^e century, and its calculations have been carried out since the 1950s, notes Duncan Agnew. “But the novelty of my work is to show the extent of the influence of melting ice on the rotation of the Earth. A change that didn’t exist before”, He said. He predicts the slowdown is so great that it could delay a possible transition to negative second until 2029. If not for the effects of global warming, it would undoubtedly have to be added in 2026.

This delay is greatly welcomed by metrologists, as it leaves them “more time to decide whether 2035 is the best date to eliminate the leap second or whether it should be abandoned sooner”– responded Patricia Tavella from the BIPM.