Days on Earth are Getting Longer

December 15, 2015 | Joanne Kennell

artistic depiction of an earth inside a sundial
Photo credit: geralt/Pixabay

And Earth’s core holds the answer to why.

If you have ever thought there is not enough time in a day, you are in luck.  As it turns out, Earth’s rotation is slowing, therefore our days are getting longer.

As the polar ice caps melt, the meltwater from these glaciers not only causes sea levels to rise, but also shifts mass from the poles to the equator.  This shift slows down Earth’s rotation.  The gravitational pull from the Moon also contributes to the slowdown, however, the combination of the Moon and rising sea-levels is not enough to explain the degree of slowing that has been observed.  So scientists are looking to the Earth’s core.

SEE ALSO: How Gravity Changes Time: The Effect Known as Gravitational Time Dilation

“In order to fully understand the sea-level change that has occurred in the past century, we need to understand the dynamics of the flow in Earth's core,” says Mathieu Dumberry, a professor in the Department of Physics at the University of Alberta.

Dumberry is one of only a few people in the world investigating changes in Earth’s rotation, and he is using his expertise in Earth’s core-mantle to explain the observations.  “Over the past 3,000 years, the core of the Earth has been speeding up a little, and the mantle-crust on which we stand is slowing down.”

As it turns out, a century from now, the length of a day will have increased by 1.7 milliseconds.  Now this may not sound like much, but Dumberry notes that this is a cumulative effect that adds up over time.

Since the scientists involved in the study had to figure out why there were discrepancies between the estimated and observed slowing of Earth’s rotation, they are now very confident in their ability to predict sea level changes up to the end of the 21st century.  “This can help to better prepare coastal towns, for example, to cope with climate change," says Dumberry. "We're talking billions of dollars of infrastructure here.”

I am okay with the days getting longer, as long as work days stay the same length.

If you are curious as to what would happen if Earth stopped spinning entirely, find out here.

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