Melting
ice sheets changing the way the Earth wobbles on its axis, says Nasa
‘Dramatic’
shift in polar motion attributed to effects of global warming and the
impact humans are having on the planet
Associated
Press
Saturday
9 April 2016 01.35 BST
Global warming is
changing the way the Earth wobbles on its polar axis, a new Nasa
study has found.
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 on 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. But that has changed with this century,
and now it’s moving toward England, according to study lead author
Surendra Adhikari at Nasa’s Jet Propulsion Lab.
“The recent shift
from the 20th-century direction is very dramatic,” Adhikari said.
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 that “this highlights how real and profoundly large an
impact humans are having on the planet.”
Since 2003,
Greenland has lost on average more than 272 trillion kilograms 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 124 trillion kgs of ice and East Antarctica gains
about 74 trillion kgs of ice yearly, helping tilt the wobble further,
Ivins said.
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, and he said this new study takes his work a step further.
“There is nothing
to worry about,” said Chen, who wasn’t part of the Nasa study.
“It is just another interesting effect of climate change.”
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