In a strange twist, global warming appears to be helping out timekeepers by delaying the need for history’s first “negative leap second” by three years, a study published last week suggested.
Experts fear that introducing a negative leap second – a minute withonly 59 seconds – into standard time could cause havoc on computersystems across the world.
For most of history, time was measured by the rotation of the Earth.
However, in 1967, the world’s timekeepers embraced atomic clocks–which use the frequency of atoms as their tick-tock – ushering in a more precise era of timekeeping.
But in recent years a new problem has emerged that few saw coming: Earth’s rotation has been speeding up, overtaking atomic time.
This means that to bring the two measurements in sync, timekeepers may have to introduce the first ever negative leap second.
“This has never happened before, and poses a major challenge to making sure that all parts of the global timing infrastructure show the sametime,” said Duncan Agnew, a researcher at the University ofCalifornia, San Diego.
“Many computer programs for leap seconds assume they are all positive, so these would have to be rewritten,” he told AFP.
Partly using satellite data, Agnew looked at the rate of the Earth’s rotation and the effect of its slowing core for the new study published in the journal Nature.
He determined that if not for climate change, a negative leap second might have needed to be added to UTC as soon as 2026.
But starting from 1990, melting ice in Greenland and Antarctica hasslowed down the Earth’s rotation, the study said. This has delayed the need for a negative leap second until at least 2029, it added.
“When the ice melts, the water spreads out over the whole ocean; this increases the moment of inertia, which slows the Earth down,” Agnew said.
If the need for an “unprecedented” negative leap second was delayed, that would be “welcome news indeed,” Patrizia Tavella, the head of the International Bureau of Weights and Measures, which is responsible for UTC, commented in Nature.