Melting of glaciers near the Earth's poles and the resulting rise in sea level is partly slowing down the Earth's rotation, thereby increasing the length of our days, a new study suggests.
Melting of glaciers near the Earth’s poles and the resulting rise in sea level is partly slowing down the Earth’s rotation, thereby increasing the length of our days, a new study suggests.
Scientists are studying past changes in sea level in order to make accurate future predictions of the consequence of climate change, and they are looking down to Earth’s core to do so.
“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,” said Mathieu Dumberry, a professor in physics at the University of Alberta in Canada.
The connection is through the change in the speed of Earth’s rotation. Melt water from glaciers not only causes sea-level rise, but also shifts mass from the pole to the equator, which slows down the rotation.
The gravity pull from the Moon also contributes to the slow down, acting a little like a leaver break.
However, the combination of these effects is not enough to explain the observations of the slowing down of Earth’s rotation: a contribution from Earth’s core must be added.
“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,” said Dumberry.
As a consequence of Earth rotating more slowly, the length of our days is slowly increasing. In fact, a century from now, the length of a day will increase by 1.7 milliseconds, researchers said.
This may not seem like much, but Dumberry notes that this is a cumulative effect that adds up over time.
The scientists involved in the study are confident in predicting sea level to the end of the 21st century.
“This can help to better prepare coastal towns, for example, to cope with climate change. We’re talking billions of dollars of infrastructure here,” said Dumberry.