Environment & Energy
Related: About this forumNASA: Global warming is now changing how Earth wobbles
Global warming is shifting the way the Earth wobbles on its polar axis, a new NASA study finds.Melting ice sheetsespecially in Greenlandare 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. But that has changed with this century and now it's moving toward England, said 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 "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.
...http://m.phys.org/news/2016-04-nasa-global-earth.html
PatrickforO
(14,586 posts)to me at all.
It sounds much more like an existential threat to our species.
muriel_volestrangler
(101,353 posts)Compared with the move of climate conditions due to global warming of kilometres per year, how would this be an existential threat?
Nihil
(13,508 posts)> Since (2000), however, the new study finds that the motion shifted sharply
> and now the North Pole is moving towards the U.K. and Europe.
> The motion has also sped up, though it still isn't very large.
> The movement towards Canada was at around 7 to 8 centimeters per year,
> Adhikari said, and the movement towards the U.K. is now about 16 to 18 centimeters
> per year.
Although the amounts are small (tens of centimetres per year), the fact that
the change was sudden rather than gradual and that, in addition, the rate has
increased 100% in this new direction is genuine cause for concern.
The rotation of the planet is is an energy balance on a scale that is almost
literally incredible - hard to comprehend or believe when you see the numbers
turned into everyday terms.
For this immense balancing act to change direction *and* magnitude so suddenly
(effectively instantaneous in geological terms) is every bit as worrying as the
degree to which, e.g., krill & low order fish are being driven to extinction by human
action. The difference is that the latter can be controlled by controlling human action
(although I'll admit that it's unlikely that any political body will even attempt - much
less succeed - at doing so) whereas the former has such inertia that it is really
mind-blowingly beyond the scope of human remediation.
It's not just that the goal-posts change, it's the entire playing field that is moving.
muriel_volestrangler
(101,353 posts)You need astronomical instruments, or GPS, to detect it. The planet has moving tectonic plates, and over immense time periods,
Does this 'have inertia'? Literally, I would say it doesn't. It's not a 'balancing act' - it's just physics, and the movement of mass around the planet will produce this response. The Earth has angular momentum, and it's going to keep that; this is just exactly where the surface features are aligned with the momentum.
Being a hundred metres closer or further from a pole, over a hundred years, would make no difference to us compared with the actual temperature effects in the atmosphere, or sea level rise, over that time. It's another way to measure the rate of ice melt (though it would, I think, be a difficult calculation to make, because you'd have to take into account melting at both poles, and what longitudes it's happening at). But extinction is for good; the exact position of the poles is of scientific interest (and for calibrating GPS, so they'll have to continue to measure it), but not something that will change any ecology.