Climate change could affect timekeeping

Accelerating melt from Greenland and Antarctica is adding extra water to the world's seas, redistributing mass. That is very slightly slowing the Earth's rotation. But the planet is still spinning faster than it used to. The effect is that global timekeepers may need to subtract a second from our clocks later than would otherwise have been the case. Coordinated Universal Time (UTC) - which is used by most of the world to regulate clocks and time - is calculated by the Earth's rotation. But the Earth's rotation rate is not constant and can therefore have an effect on how long our days and nights are. Changes to the planet's liquid core have meant the Earth has been spinning slightly quicker. Since the 1970s, to correct for this, about 27 leap seconds have been added to the global clock, with timekeepers planning on subtracting a second for the first time in 2026. This is known as a "negative leap second." Ice sheets are now losing mass five times faster than they were 30 years ago, meaning that the negative leap second change will not be needed until 2029, the study suggests.