Global warming shifting Earth’s wobble

The Associated Press
Seth Borenstein

WASHINGTON—Global warming is shifting the way the Earth wobbles on its polar axis, a new NASA study finds.
Melting ice sheets, especially in Greenland, are changing the distribution of weight on Earth.
And that has caused both the North Pole and the wobble, which is called polar motion, to change course, according to a study published Friday in the journal, “Science Advances.”
Scientists and navigators have been accurately measuring the true pole and polar motion since 1899, and for almost the entire 20th century they migrated a bit toward Canada,” said study lead author Surendra Adhikari at NASA’s Jet Propulsion Lab.
“But that has changed with this century and now it’s moving toward England,” Adhikari noted.
“The recent shift from the 20th-century direction is very dramatic.”
While scientists say the shift is harmless, it is meaningful.
Jonathan Overpeck, professor of geosciences at the University of Arizona, who wasn’t part of the study, said “this highlights how real and profoundly large an impact humans are having on the planet.”
Since 2003, Greenland has lost, on average, more than 600 trillion pounds of ice a year—and that affects the way the Earth wobbles in a manner similar to a figure skater lifting one leg while spinning, said NASA scientist Eirk Ivins, the study’s co-author.
On top of that, West Antarctica loses 275 trillion tons of ice while East Antarctica gains about 165 trillion tons of ice yearly, helping tilt the wobble further, Ivins added.
They all combine to pull polar motion toward the east, Adhikari said.
Jianli Chen, a senior research scientist at the University of Texas’ Center for Space Research, first attributed the pole shift to climate change in 2013.
He said this new study takes his work a step further.
“There is nothing to worry about,” stressed Chen, who wasn’t part of the NASA study.
“It is just another interesting effect of climate change.”

Posted in Uncategorized