National Physical Laboratory

Leap seconds: Have your say

Leap seconds are used to provide a link between the variable time scale of the solar day and the extremely stable time scale based on atomic clocks, like those housed at the National Physical Laboratory (NPL).

Image courtesy of iStockphoto
Image courtesy of iStockphoto

There is ongoing debate over whether or not to abolish leap seconds and allow solar time to gradually drift away from the atomic time scale. Before a final decision is due to be made in 2015, the UK government has established Leap Seconds - The UK Public Dialogue to allow UK citizens and stakeholders to debate the issues.

Since 1972, the world's time scale, known as Coordinated Universal Time (UTC), has been based on counting seconds from atomic clocks. These atomic clocks are now over a million times more regular than the Earth's rotation, which is gradually slowing down due to the action of the tides, while also being disturbed by factors such as tectonic activity and polar ice distribution.

The International Earth Rotation and Reference Systems Service (IERS) monitors the rotation of the Earth and decides twice a year whether or not there will be a leap second to keep it in sync with the atomic time scale. The most recent leap second was inserted on 30 June 2012.

Leap seconds are seen by some as an imperfect solution to the problem of syncing atomic and solar time. It has been suggested that they could cause major crashes in computer systems due to their inherent unpredictability - the insertion of a leap second is only announced five months in advance. On the other hand, leap seconds have already been in use for over 40 years and the international community needs to be sure the long term consequences are understood, before making any changes to a system that works for the vast majority of users.

David Willetts, Minister of State for Universities and Science, said:

"My view is that without leap seconds we will eventually lose the link between time and people's everyday experience of day and night and this public dialogue will give everyone the opportunity to have their say on this important issue. It will also help to inform our position ahead of next year's decision on the future of leap seconds."

A number of public discussions will take place and these will feed into a National Summit, due to be held in July 2014, which will bring together members of the public, stakeholders and policy makers. The findings will inform the UK position at the World Radio Conference in 2015, where the consensus of the international community will determine the future of the leap second.

For further information, please visit Leap Seconds - The UK Public Dialogue

Find out more about Leap Seconds

Last Updated: 5 Jun 2014
Created: 5 Jun 2014


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