CGPM votes to end leap seconds citing IoT update difficulties

Time Lords vote to abandon leap seconds

The General Conference on Weights and Measures (CGPM), the body responsible for harmonizing Universal Time (UT1), calculated from the Earth's variable rotation, with the Coordinated Universal Time (UTC) standard, has voted to stop introducing leap seconds. The decision was taken at the organization's 28th meeting last week, where delegates cited the growing difficulty of updating billions of connected devices as a major reason for the change.

The CGPM keeps UT1 and UTC in sync by adding leap seconds when the planet's spin slows. In recent years the organization had even pondered a negative leap second because Earth's rotation has sped up slightly.

Negative leap second seen as major risk

In a resolution posted after the vote, the CGPM wrote that a negative leap second has never been applied and is considered to pose a high risk of causing anomalies and disruption to critical infrastructures that are largely unprepared. Preparing for such an event would require financial investment from industries that rely on time synchronization, estimated to be similar to their preparations for the millennium bug.

The world spent an estimated $300 billion to $600 billion remediating software ahead of January 1, 2000, and historians now cite that range as the global Y2K remediation cost, though it is widely thought the money was not well spent.

IoT devices and certificate failures

The resolution warns that the growing influence of IoT technologies, dispersed multi-sensor systems, smart grids and virtual services creates an increasing risk of malfunction when any leap second is inserted, especially a negative one. The CGPM also raised concern that global service providers use different mitigation methods in their server systems to avoid time steps, leading to inconsistency in timing between systems that does not conform to the SI standard second.

With myriad manufacturers and few standards for how devices should behave, many IoT products ship without facilities for easy updates, meaning billions of devices could fail to implement a leap second. Because digital certificates include a notbefore value, many systems would reject misbehaving certificates. That raises the scenario in which a carrier's network decides its own customers are not trustworthy enough to connect if its modems cannot accommodate the extra time.

Continuous UTC to replace leap seconds

The CGPM's replacement is a scheme called "Continuous UTC" that allows UT1 and UTC to diverge by up to 3,600 seconds. It comes into force next year. The organization notes that humanity has extensive practice adding and removing hours through Daylight Saving time.

Sources: The Register