Scientists have observed that the Earth’s rotation speed is increasing, making it an unexpected phenomenon which is resulting in shorter days. June 29, 2022 was observed to be a record-breaking shorter day, 1.59 milliseconds shorter than an average 24-hour day. July and August 2025 are speculated to witness even shorter days. Historically, Earth’s rotation was slowed due to tidal friction caused by Moon’s gravity lengthening a day by about 2.3 milliseconds, which however, changes after 2020, when the planet witnessed an unexpected increase in rotational speed. What could have caused this sudden increase in the speed?
Several geophysical and climatic factors are responsible for the change. These include the melting of ice sheets from the last Ice Age leading to changes in the planet’s landmasses causing a reduction in Earth’s moment of inertia and thereby increasing its rotational speed. It is also caused by variations in atmospheric pressure, winds, ocean currents or movements within the Earth’s molten core and mantle, which influence rotation on decadal scales. Major earthquakes are capable of redistributing Earth’s mass which can speed up the rotation alongside the periodic wobbles in the Earth’s rotational axis.
How to deal with this shift in rotational speed and timeline? The solution lies in the adoption of a negative leap second. A negative leap second involves subtracting a second from UTC to compensate for Earth’s faster rotation. This would be a historic first as previously, all leap seconds have been positive. However, the IERS has not yet scheduled such an adjustment, and international bodies, including the General Conference on Weights and Measures in 2022, have proposed phasing out leap seconds by 2035 due to their disruptive effects on digital systems. What effects does it have on global technological systems.
A negative leap second could disrupt satellite communication that rely on precise timekeeping for synchronizing signals and transmitting data. It could also affect the Global Navigation Satellite Systems (GNSS) that depend on atomic clocks for precise positioning, velocity and timing, potentially causing temporary mismatches in positioning data. High-frequency trading (HFT) systems executing millions of trades per second, being highly sensitive to time discrepancies can witness execution errors or dispute of transactional order.
Alongside the global disruptions, India, specifically, is also expected to face implications of the negative leap second. The Indian Space Research Organisation (ISRO) operating NavIC (a regional GNSS), communication satellites and interplanetary space missions like Chandrayaan and Mangalyaan, heavily relies on precise timing, synchronization and data transmission which will be affected by any changes in the time unit leading to positioning and communication errors. A negative leap second would also impact the timekeeping institutions, which is National Physical Laboratory (NPL) in case of India which maintains Indian Standard Time (IST) using atomic clocks. It would require careful coordination to adjust clocks without disrupting national timekeeping services while communicating the need for a negative leap second to government agencies, industries, and the public would be critical to avoid confusion. India’s tech industry would require updating time-sensitive applications, trading platforms necessitating robust testing and cloud and data centers updating Network Time Protocol (NTP) servers and database management systems to keep up with the changes in time.
By understanding the causes, preparing for technical disruptions, and collaborating internationally, India can navigate this temporal anomaly while maintaining its position as a technological and scientific leader. As the world considers phasing out leap seconds by 2035, the negative leap second of 2025 may serve as a critical test of global and Indian readiness for managing Earth’s dynamic rotation.
Riya Goyal is a trainee journalist at Cult Current. The views expressed in the article are
her ownand do not necessarily reflect the official stance of Cult Current.