Overview
- The Generalkonferenz für Maß und Gewicht voted Thursday in Versailles to stop inserting leap seconds into Coordinated Universal Time, with the continuous-UTC rule taking effect on 20 May 2027 and allowing UTC to diverge from astronomical time (UT1) by up to 3,600 seconds.
- Officials cited rising risk of a never-before-used negative leap second and documented incidents where one-second adjustments disrupted airline booking, energy and telecom systems as a key reason for the change.
- The Bureau International des Poids et Mesures published a scientific roadmap led by Dr. Patrizia Tavella that lists technical prerequisites for redefining the second, including reliable international clock comparisons, ultra-precise signal distribution and corrections for relativistic height differences.
- A formal proposal to redefine the second using optical atomic clocks is being worked toward for the 2030 CGPM, but any redefinition will require proof that global comparison and transfer methods meet strict accuracy and consistency requirements.
- For most people daily clocks and schedules will be unchanged for generations, while astronomers, geodesists, GNSS operators and some software and infrastructure teams will need to adapt to a UTC that will slowly drift from the position of the Sun.