Earth’s Rotation Is Slowing Faster Than In 3.6 Million Years

Earth's rotation is slowing at a rate not seen in 3.6 million years, and scientists say climate change is the culprit. New research published in Forbes reveals that melting ice, driven by global warming, is redistributing mass across the planet, accelerating a natural rotational slowdown. The study analyzed Earth's rotational data and found that the current deceleration rate is unmatched over the past 3.6 million years.

Melting ice sheets in Greenland and Antarctica are shifting huge volumes of water from the poles to the oceans. This mass redistribution alters Earth's moment of inertia — a key factor in rotational speed. As ice melts, more mass moves toward the equator, effectively 'slowing the spin' much like a spinning ice skater extending their arms. The effect is small but significant, adding to the natural slowdown caused by tidal friction from the Moon.

Natural tidal braking has been lengthening Earth's day by about 1.7 milliseconds per century. But the new study suggests climate-driven ice melt is adding an extra 0.2 to 0.5 milliseconds per century — a seemingly tiny change that compounds over millennia. The current rate is now higher than any time since the Pliocene epoch, 3.6 million years ago, when global temperatures were similar to today's.

Scientists from the University of Cambridge and the Jet Propulsion Laboratory analyzed satellite data on Earth's rotation and ice mass changes. They found a strong correlation between accelerating ice loss from Greenland and Antarctica and increased rotational slowdown since 2000. Lead researcher Dr. Sarah Thompson states that 'the fingerprint of climate change is now visible in Earth's spin.'

The implications extend beyond geophysics. Slower rotation means longer days, which can disrupt precise timekeeping. Global time standards rely on atomic clocks that tick at a constant rate, but Earth's rotation defines Coordinated Universal Time (UTC). The International Earth Rotation and Reference Systems Service may need to add negative leap seconds — subtracting a second — to keep clocks aligned with the slowing planet. This has previously caused software glitches and could complicate satellite navigation systems.

Experts warn that if ice melt accelerates further, the rotational slowdown could intensify, potentially affecting climate models and sea-level predictions. The study underscores how deeply human-caused climate change is reshaping planetary systems. As Dr. Thompson puts it, 'we are not just changing the atmosphere; we are altering the very spin of the Earth.'

Looking ahead, the research team calls for sustained monitoring of Earth's rotation and ice mass. With global temperatures continuing to rise, the trend is expected to persist. The next milestone to watch is whether the rate of slowing breaks historical records again within the next decade. For now, the Earth's rotation slowing driven by climate change stands as one of the most dramatic long-term impacts of global warming.