Scientists reveal that the rotation of Earth's core holds a clue to understanding global sea-level rise

December 11, 2015
Mathieu Dumberry from the University of Alberta is one of only a few people in the world investigating changes in Earth rotation. Credit: John Ulan for the University of Alberta

Scientists are studying past changes in sea level in order to make accurate future predictions of this consequence of climate change, and they're 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" says Mathieu Dumberry, a professor in physics at the University of Alberta.

The connection is through the change in the speed of Earth's rotation. Melt water from glaciers not only causes , but also shifts mass from the pole to the equator, which slows down the rotation. (Picture the Earth as a spinning figure skater. The skater moves his or her arms in to spin more quickly or out to slow down.) The gravity pull from the Moon also contributes to the slow down, acting a little like a lever 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.

One of only a few people in the world investigating changes in Earth rotation, Dumberry contributed his expertise on Earth's core-mantle coupling to the study. "Over the past 3000 years, the core of the Earth has been speeding up a little, and the mantle-crust on which we stand is slowing down." 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. This may not seem like much, but Dumberry notes that this is a cumulative effect that adds up over time.

Based on their work reconciling these discrepancies, the scientists involved in the study are confident in predicting 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." Dumberry notes that this study serves as a stimulus for more work to continue investigating the deep interior of our planet.

The findings, "Reconciling past changes in Earth's with 20th century global sea-level rise: Resolving Munk's enigma," were published in the December 11, 2015 issue of the journal Science Advances.

With 12 climate change-related centres and institutes and 24 climate change-related Canada Research Chairs, the University of Alberta is committed to researching the causes and effects of . Researchers study past climate changes to better predict future changes.

Explore further: Climate surprises possibly in store for Antarctica, say researchers

More information: Science Advances, dx.doi.org/10.1126/sciadv.1500679

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9 comments

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Porgie
2.5 / 5 (8) Dec 11, 2015
So its not global warming after all. Get out the razor blades and buckets.
yep
2.2 / 5 (5) Dec 11, 2015
Water spinning in Microgravity. http://youtu.be/BxyfiBGCwhQ
Interesting how the center of the sphere hollows out.
someone11235813
5 / 5 (3) Dec 12, 2015
In fact, a century from now, the length of a day will increase by 1.7 milliseconds. This may not seem like much, but Dumberry notes that this is a cumulative effect that adds up over time.


It may be true that it "adds up over time", however I cannot help but feel underwhelmed that in one thousand years the rotation of the Earth will have slowed by two hundredths of a second. I feel fairly confident that if Humans are still here in one thousand years that science would have advanced sufficiently that that small incremental change would be fully under control.
Danie
5 / 5 (2) Dec 12, 2015
Interesting to see that there is another factor involved. However small the impact is. Also, I been hearing about the slow down of the spin of Earth, but not by how much. So this will put a few nerves at ease knowing that the sun will go nova before the slow down of rotation affect us too much.
Captain Stumpy
2.3 / 5 (3) Dec 12, 2015
Water spinning in Microgravity. http://youtu.be/BxyfiBGCwhQ
Interesting how the center of the sphere hollows out.
@yep
actually, that IS interesting... but also explainable with standard physics

the problem with the extrapolation of the water video to the Earth is that you can't account for the mass and gravity in the water video

what happens when the water is increased to a mass equivalent to Earth?
what happens when solids are introduced to a similar mass?
Again, the standard model and physics can explain it
http://ocw.mit.ed...ophysics
thingumbobesquire
3.3 / 5 (8) Dec 12, 2015

"With 12 climate change-related centres and institutes and 24 climate change-related Canada Research Chairs, the University of Alberta is committed to researching the causes and effects of climate change."

Really? And yet we always hear that really big money is being spent by the "deniers." How much of this Malthusian pseudoscience is being paid for by the burgeoning and uncollectable bubble of student debt?

plaasjaapie
3.8 / 5 (8) Dec 12, 2015
LMAO! You have to relate everything studied, however obscure, to global warming to get a slot on PhysOrg these days, apparently. :-p
MikPetter
5 / 5 (1) Dec 13, 2015
From the paper "We demonstrate that the combination of lower estimates of the 20th century GMSL rise (up to 1990) improved modeling of the GIA process and that the correction of the eclipse record for a signal due to angular momentum exchange between the fluid outer core and the mantle reconciles all three Earth rotation observations. This resolution adds confidence to recent estimates of individual contributions to 20th century sea-level change and to projections of GMSL rise to the end of the 21st century based on them."
Vietvet
1 / 5 (1) Dec 13, 2015
@MikPeter.

Thanks for posting that quote, There are concepts that take 3D thinking to grasp and this an example. This study does nothing to negate AGW, it actually reinforces it.

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