Climate change is making days (a little) longer, study says

Now are we affecting time itself?

Two new scientific studies suggest that global warming is changing the rotation of the Earth and is also increasing the length of day "at an unprecedented rate."

Here's what's happening: As the planet heats up, ice sheets in Greenland and Antarctica are melting, and this water from the polar regions is flowing into the world’s oceans – and especially into the equatorial region. This is changing the Earth's shape and thus slowing its speed of rotation.

'A shift in mass'

Each year, as the globe warms, hundreds of billions of tons of ice melt into the Earth's oceans.

“This means that a shift in mass is taking place, and this is affecting the Earth’s rotation,” explained co-author Benedikt Soja of the Swiss University ETH Zurich, in a statement.

Thus, as the Earth is turning more slowly, the days are getting longer, albeit only minimally, on the order of a few milliseconds a day. But it's potentially enough to affect GPS, communications and even space travel.

Previous study had similar finding

This isn't the first study to make such a claim: A 2021 study found that melting glaciers around the world – a result of rising atmospheric temperatures from the burning of fossil fuels – redistributed enough water to cause the location of the North and South Poles to move eastward since the mid-1990s.

Climate scientist Vincent Humphrey of the University of Zurich, who was not involved in the 2021 study nor the new research, previously explained that the Earth spins around its axis like a top. If the weight of a top shifts, the spinning top would lean and wobble as its rotational axis changes.

The same thing happens to the Earth as weight is shifted from one area to the other.

'Great responsibility'

Another cause of the Earth's rotational slowdown is tidal friction, which is triggered by the moon, according to a statement from ETH Zurich. However, the new research comes to a surprising conclusion: "If humans continue to emit more greenhouse gases and the Earth warms up accordingly, this would ultimately have a greater influence on the Earth’s rotational speed than the effect of the moon, which has determined the increase in the length of the day for billions of years."

Soja said that “we humans have a greater impact on our planet than we realize, and this naturally places great responsibility on us for the future of our planet.”

One finding from the second study, which was published in Nature Geoscience, also stands out: That the processes on and in the Earth are interconnected and influence each other. Ongoing climate change could "be affecting processes deep inside the Earth and have a greater reach than previously assumed," said Mostafa Kiani Shahvandi, one of Soja’s doctoral students and lead author of the study.

Important for space travel

In addition to sensitive GPS and communications devices, the change in Earth's rotation could impact space travel: “Even if the Earth’s rotation is changing only slowly, this effect has to be taken into account when navigating in space – for example, when sending a space probe to land on another planet,” Soja said.

Even a slight deviation of just one centimeter on Earth can grow to a deviation of hundreds of meters over the huge distances involved. “Otherwise, it won’t be possible to land in a specific crater on Mars,” he said.

The two studies appeared in the peer-reviewed journals Nature Geoscience and the Proceedings of the National Academy of Sciences.