World timekeepers vote to scrap the 'leap second' and allow clocks to drift by a full hour from 2027

Delegates from 69 countries gathered at the General Conference on Weights and Measures in Versailles on Thursday and voted to abolish the leap second, bringing to an end five decades of adjustments made to keep atomic time in step with the Earth's rotation. The change takes effect on 20 May 2027, World Metrology Day, and will allow Coordinated Universal Time to drift up to one full hour from astronomical time before any correction is made. Dr Setnam Shemar of the UK's National Physical Laboratory called it 'a good decision overall'. The new correction — a leap hour rather than a leap second — may not need to be applied for thousands of years.

Since its introduction in 1972, the leap second has been inserted into timekeeping 27 times; despite this, it crashed Reddit and LinkedIn in 2012 and caused Cloudflare outages in 2016.

Tech giants including Meta, Google and Amazon had for years pushed for the leap second to be scrapped, describing it as 'a major source of pain' for infrastructure worldwide.

Dawn, noon and dusk could eventually fall up to an hour off clock time — but scientists say the drift will be so slow it may take millennia to matter.