Earth’s Days Are Getting Longer. Climate Change Is to Blame

Why It Matters

The subtle deceleration threatens precision‑dependent systems such as satellite navigation and underscores climate change’s far‑reaching physical impacts.

Key Takeaways

• Day length increasing 1.33 ms per century
• Climate change now outweighs lunar influence on rotation
• Rising sea levels redistribute mass, slowing Earth's spin
• Impacts precise satellite navigation and timing systems
• Study uses deep‑learning to model historic sea‑level changes

Pulse Analysis

The length of an Earth day is not a fixed 24‑hour constant; it fluctuates in response to forces that shift the planet’s angular momentum. Historically, lunar tides and internal geophysical processes have been the dominant drivers of these variations. A new study published in the Journal of Geophysical Research: Solid Earth reveals that the current slowdown—adding roughly 1.33 milliseconds to each day per century—is the fastest recorded in the past 3.6 million years. Researchers arrived at this conclusion by analyzing fossil chemistry to reconstruct ancient sea‑level changes and correlating them with day‑length data.

The acceleration of day‑lengthening is directly tied to climate‑induced sea‑level rise. As glaciers melt and polar ice sheets recede, water mass migrates from high latitudes toward the equatorial bulge, effectively stretching the planet’s “arms” and reducing its spin rate, much like a figure skater extending their limbs. The team employed a probabilistic deep‑learning algorithm to model the complex physics of sea‑level dynamics, achieving unprecedented precision in linking mass redistribution to rotational deceleration. Their findings suggest that, by the end of the century, anthropogenic climate effects could eclipse lunar torque as the primary influence on Earth’s rotation.

While a millisecond shift may seem trivial, it carries tangible consequences for sectors that rely on ultra‑precise timing. Satellite navigation, geodesy, and space‑flight operations depend on accurate Earth‑rotation parameters; even minor errors can cascade into positioning inaccuracies and communication delays. The study underscores the broader, often overlooked, systemic impacts of climate change, extending beyond temperature and weather extremes to fundamental planetary mechanics. Policymakers and engineers will need to incorporate evolving rotational data into future models, and continued interdisciplinary research will be essential to monitor and mitigate these subtle yet significant effects.