Leap second gets one more week

Timekeepers at a meeting in Geneva have failed to agree on a proposal to abolish the 40-year-old practice of adding the occasional second to atomic time, in order to bring it in alignment with world time as told by the rotation of the Earth.

The International Telecommunication Union put off the decision at Thursday’s meeting, saying more study was needed into whether to scrap the leap second.

The extra moment is added to atomic clocks to keep them in sync with the earth’s rotation, which is slowed by the gravitational pull of the Sun and the Moon.

“The decision that we will take is that it is not approved and the matter is to be referred to study group seven for more study,” Alan Jamieson, chairman of the ITU’s Radiocommunication Assembly, said at the close of the meeting.

The debate, which has lasted a decade, has split countries that are members of the ITU.

Every time that a second is added, the world’s computers must be manually adjusted, a practice that is costly and cumbersome, and boosts the risk of error.

Without the leap second, however, atomic clocks would run faster than solar time by about 15 seconds every 100 years, experts believe.

“The social, legal, religious implications [of scrapping the leap second] have not been studied properly,” said British representative Stephen Bond, while the US said the increasing use of satellite-based navigation systems favoured its suppression.

A leap second has been added on 24 occasions since the ITU first defined Co-ordinated Universal Time (UTC) 40 years ago.

When required, they are always introduced at midnight on June 30 or December 31.

Representatives from 70 countries were present at Thursday’s gathering, with the US, France and Japan among those favouring the scrapping of the leap second, while Britain, China and Canada said that more study was needed.

“The use of these seconds introduces the possibility of technical problems each time they are inserted into UTC,” said US representative Dick Beaird. “This can impact the safety and reliability of systems dependent on precision time keeping.

“Systems for space activity, global navigation, satellite systems and so forth require a continuous, uninterrupted time reference.”

Bond, the British representative, said the decision was one of “great significance” that would be reflected on by future generations and its approval would be premature.

“The common public understanding of the civil time of day is that it is closely linked to the earth’s rotation,” he said.

“There may be public opposition to ending the linkage and the fact that the day will no longer be matched by a single rotation of the earth.”

The future of the leap second will be further debated at the ITU’s World Radiocommunication Conference beginning next week.

Sanjay Acharya, a spokesman for the ITU, however, said that any formal decision would likely be deferred until 2015.