Earth’s Rotation Slows
Scientists have discovered that melting polar ice, driven by human activity and fossil fuel emissions, is slowing Earth’s rotation. As ice melts and water shifts toward the equator, the planet’s spin is slightly delayed, making each day fractionally longer.
Mechanics of the Effect
The effect is similar to figure skating: when mass moves away from an axis, rotation slows. Currently, human-induced climate change is adding roughly 1.33 milliseconds per century to the length of a day, the fastest climate-driven increase in 3.6 million years.
Comparison to Natural Forces
Tidal interactions with the Moon naturally slow Earth at 2.4 milliseconds per century. By the end of this century, melting ice due to climate change is expected to surpass lunar effects as the primary factor affecting Earth’s rotation.
Implications for Technology
Even millisecond changes matter for precision technologies:
- GPS navigation relies on exact timing.
- Deep-space spacecraft require precise rotation calibration to land safely.
Without accounting for these fractions of a second, positioning errors could reach hundreds of meters.
Human Impact and Long-Term Significance
Though the immediate threat to humans is minimal compared to wildfires or storms, the finding illustrates the broad scale of anthropogenic effects. Researchers emphasize the importance of monitoring Earth’s rotation to adapt technology and infrastructure.
Expert Commentary
“It’s remarkable that human activity now rivals the Moon in influencing Earth’s rotation,” says Benedikt Soja of ETH Zurich. David Holland from New York University highlights the rapid impact since the industrial era began about 150 years ago, noting the unprecedented summer ice melt in the Arctic.
