Earth’s Rotation Slowdown: Shorter Days Explained

The Earth rotates a little more slowly. The change is minimal, but measurable: the length of day on our planet is increasing, and researchers attribute the current changes to human factors.

According to a recent study published in Journal of Geophysical Research: Solid Earth, The Earth’s rotation has almost never slowed down so noticeably in the last few million years as in the last few decades. Researchers from Austria and Switzerland believe this confirms that climate change is influencing the length of the day on Earth.

Imperceptible but measurable effects

In everyday life, this braking is not noticeable. Currently, the planet’s rotation is lengthening by about 1.33 milliseconds per century. However, this increase could have effects in areas that depend on the Earth’s rotation, such as precise time measurement or space navigation, the study points out.

In school they are taught that a day lasts 24 hours because it takes the Earth that long to make a complete revolution on its own axis. However, strictly speaking, the duration of the rotation varies both by the attraction of the Moon and by geophysical processes inside the Earth, on its surface and in the atmosphere.

In previous research, Mostafa Kiani Shahvandi, from the University of Vienna, and Benedikt Soja, from ETH Zurich, showed that sea level is rising due to accelerated melting of the poles and glaciers, which in turn slows down the Earth’s rotation. Kiani Shahvandi explained in a statement from the University of Vienna that the phenomenon can be compared to a figure skater who spins more slowly when she extends her arms.