Saturday, December 12, 2015

Scientists may have just solved one of the most troubling mysteries about sea-level rise

Interesting story that explains how melting ice can change the rotation of Earth. This matches the I AM America information. - Lori

[Washington Post] Scientists have announced a potential solution to a tantalizing puzzle about sea-level rise that’s remained unsolved for more than a decade. In doing so, they’ve helped confirm scientists’ latest estimates of 20th-century glacial melting and our understanding of how sea-level rise fundamentally affects the planet — down to the way it spins on its axis.
At issue is a scientific quandary known as “Munk’s enigma,” which was introduced by famed oceanographer Walter Munk in a 2002 paper published in Proceedings of the National Academy of Sciences. The enigma refers to a key discrepancy between the amount of sea-level rise believed to have occurred during the 20th century and the effects it should have produced on the planet — specifically, on the Earth’s rotation.
That’s right — in addition to all the devastating and obvious effects sea-level rise will produce on the planet, such as flooding and erosion, sea-level rise also has the more subtle, but nonetheless mind-boggling ability to alter the way the Earth rotates on its axis.
“If you melt ice sheets or glaciers, which happen to be close to to the poles, and all of that mass moves from the poles toward the equators, that movement is very similar [to] a figure skater who puts her arms out,” said the new paper’s lead author, Jerry Mitrovica, a professor of geophysics at Harvard University. “The melting of glaciers acts to slow the spin of the Earth in a measurable way.”
Additionally, glacial melt can also cause the Earth’s rotation to wobble a little, since “the melting of glaciers isn’t perfectly symmetrical, and the water will move more in some parts of the Earth than others,” Mitrovica said.
Theoretically, one should be able to look at calculations of how the Earth’s rotation has changed over the years, compare these changes with the amount of glacial melting believed to have occurred in the same time frame, and find that the two measurements reinforce each other. Read More