Climate change is causing the days to become slightly longer

This was reported by a research team in the journal “Proceedings” of the American National Academy of Sciences (“PNAS”).

The Moon’s pull on the Earth slows the Earth’s rotation
If climate change is not slowed down, the effect could become larger than the influence of the moon on the Earth’s rotation, explains the group led by Mostafa Kiani Shahvandi of ETH Zurich. The moon’s gravity creates tidal forces on Earth, which are particularly visible in the ebb and flow of the tides. The moon’s ‘pull’ on the Earth slows the Earth’s rotation slightly and thus lengthens the day.

Climate also has a small influence on the Earth’s rotation, which can be measured with modern satellites.

The increase in day length varies
The researchers’ calculations showed that the climate-related increase in day length fluctuated significantly over the 20th century: between 0.31 milliseconds per century (1960 to 1980) and 1.00 milliseconds per century (1920 to 1940).

For the first two decades of the 21st century, researchers calculated an average climate-related increase in day length of 1.33 milliseconds per century – statistically significantly more than in the entire 20th century.

“These results, through their impact on day length, show that the mass transport from the poles to the equator due to climate change in the past 20 years has been unprecedented compared to the previous 100 years,” the researchers said.

Mass shifts in the Earth’s mantle
The effect that counteracts the movement of water masses as the ice melts was also taken into account: mass movements in the Earth’s mantle. Kilometers of ice press the land masses of Greenland and Antarctica into the viscous part of the Earth’s mantle on which the tectonic plates move. When the ice melts, the land masses become lighter and rise because the viscous mantle mass flows underneath them. According to calculations, the effect is currently minus 0.8 milliseconds per century, which shortens the length of the day.