Earth’s Rotation Speed is Increasing: Scientists Record Shortest Days in Decades
New Delhi, July 2025 – In a striking development, Earth’s rotation appears to be subtly accelerating, leading to some of the shortest days recorded in decades. According to global timekeeping institutions and geophysical observatories, recent years have seen days that are milliseconds shorter than the standard 24-hour period.
In particular, July 19, 2020, marked the shortest day since precise measurements began in the 1960s. The day was 1.4602 milliseconds shorter than the average, an anomaly that set off widespread scientific interest.
Experts attribute this unexpected phenomenon to a variety of complex geophysical factors:
- Post-glacial rebound – The melting of glaciers since the last Ice Age causes Earth’s crust to shift and adjust, redistributing mass and affecting rotational speed.
- Movement in the Earth’s molten core – Fluid dynamics in the outer core can alter the planet’s moment of inertia, akin to how a figure skater spins faster when pulling in their arms.
- Climate change – Melting polar ice and rising sea levels are subtly shifting Earth’s mass towards the equator.
- Atmospheric and oceanic dynamics – Large-scale wind patterns and ocean currents also influence the Earth’s angular momentum.
While these changes are minuscule—measured in milliseconds—they hold significance for global timekeeping. Modern systems such as GPS, stock exchanges, satellite communications, and power grids rely on extremely precise time synchronization. Deviations can potentially lead to major technical disruptions.
To maintain coherence between atomic time (International Atomic Time or TAI) and astronomical time (based on Earth’s rotation), leap seconds are occasionally added. However, with the current acceleration trend, scientists are now contemplating the possibility of subtracting a leap second, something that has never been done before.
A Long-Term Trend or a Temporary Shift?
It’s important to note that Earth’s rotation speed is not increasing linearly. Instead, it fluctuates due to a variety of natural cycles and interactions. Historically, the Earth’s spin has gradually slowed down over geological time due to tidal friction from the Moon. The current increase could be part of a temporary oscillation.
Geophysicists continue to monitor the phenomenon closely, emphasizing that while the change is not cause for alarm, it does underline the dynamic and interconnected nature of Earth’s systems.
Probable UPSC Mains Questions
GS Paper I – Geography
- “The Earth’s rotation speed is not constant. Discuss the causes and consequences of the observed changes in Earth’s rotational velocity.” (250 words)
- “How does the redistribution of Earth’s mass affect its rotational characteristics? Examine with reference to glacial melting and climate change.” (250 words)
GS Paper III – Science & Technology / Environment
- “What are the implications of Earth’s accelerating rotation on modern technological systems and global timekeeping practices?” (150/250 words)
- “In the context of precision timekeeping, analyze the role and relevance of leap seconds in a world of accelerating Earth rotation.” (150 words)
- “Explain the interplay between Earth’s geophysical processes and planetary dynamics. How can shifts in Earth’s rotation affect human life and infrastructure?” (250 words)
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