According to the study, the planet is rotating a tad bit faster than it used to, and hence, we might have to subtract a second in a few years.
- Ice melting at both of Earth’s poles has been counteracting the planet’s burst of speed and is likely to have delayed this global second of reckoning by about three years.
- For thousands of years, the Earth has been generally slowing down, with the rate varying from time to time.
- Earth’s speeding up because its hot liquid core acts in unpredictable ways, with eddies and flows that vary. The core has been triggering a speedup for about 50 years, but the rapid melting of ice at the poles since 1990 masked that effect.
- Melting ice shifts Earth’s mass from the poles to the bulging centre, which slows the rotation much like a spinning ice skater slows when extending their arms out to their sides.
Timekeeping on Earth
- Timekeeping on Earth is determined by atomic clocks, but it is also aligned with Earth’s rotation, mainly for historical reasons.
- Because the planet’s rate of rotation fluctuates, this alignment is maintained with the occasional addition of ‘leap seconds’ to the official time standard. It is called the coordinated universal time (UTC).
- The new international reference, known as coordinated universal time (UTC), is set by atomic clocks, but kept apace with the rotational angle of Earth, which is known as universal time (UT1).
- Since 1972, UTC has been adjusted to meet this goal by adding 27 leap seconds.
- Now, Earth’s rotation seems to have accelerated, outpacing the time standard, and raising the possibility that an unprecedented ‘negative’ leap second might soon be required.
