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Is the Leap Second Good or Bad? We Have Until 2023 to Find Out

A decision to abolish the leap second has been delayed so that potential effects of its elimination can be studied.

The world will hold onto its leap second, at least until 2023.

The International Telecommunication Union, a part of the United Nations, decided on Thursday at the World Radiocommunication Conferences that it would delay its decision on whether to abolish the leap second so that potential effects of its elimination can be studied.

The leap second is an extra second of time added periodically to the world's clocks, but some experts have raised fears it could throw off modern technology, including banking systems, GPS, flight operators, and more.


The adjustment is meant to compensate for the differences between traditional solar time, based on the rate that the earth spins, and time kept by the world's hyper-accurate atomic clocks, which measure time by cesium atomic frequency. Without adding a leap second every few years, the time on our computers and phones would very slowly drift out of sync with the rising and setting cycle of the sun.

An extra second has been added every few years since 1972—the last one happened this summer—but the practice has been increasingly under scrutiny. Demetrios Matsakis, Chief Scientist for Time Services at the US Naval Observatory, told Motherboard earlier this year the leap second puts untold numbers of systems at risk for failure.

"We should eliminate leap seconds because of the real-world practical impossibility of reliably implementing them, due to either their inherent nature or to general lack of knowledge of their very existence," he said at the time.

Other countries, including France, Italy, and Japan also oppose the leap second, while Russia and Britain support it. All countries were supposed to come to a mutual decision on a course of action during this year's ITU meeting, said Sanjay Acharya, a spokesperson for the ITU.

"If not everybody agrees, systems won't function in any case, so we do strive for consensus in decisions like these," he said. "There are very strong positions on either side of this so therefore the decision at this time was to delay the decision until 2023."

The next ITU World Radiocommunication Conference is in 2019, but the decision will be delayed until the following meeting, pending studies.

These studies will be conducted by the ITU with other organizations, including the General Conference on Weights and Measures (CGPM), the International Committee for Weights and Measures (CIPM), the International Bureau of Weights and Measures (BIPM), the International Organization for Standardization (ISO), and the World Meteorological Organization (WMO).

Leap seconds always fall at the end of June or December, but the next leap second has not yet been announced. Time will tell how many more of them remain in our future.