We’ve pumped so much groundwater that we’ve nudged the Earth's spin
We’ve pumped so much groundwater that we’ve nudged the Earth's spin
AGU press contact: Rebecca Dzombak, news@agu.org (UTC-4 hours) Contact information for the researchers: Ki-Weon Seo, Seoul National University, seokiweon@snu.ac.kr (UTC+9 hours) WASHINGTON — By pumping water out of the ground and moving it elsewhere, humans have shifted such a large mass of water th...
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edit: sorry for the wall of text. it did not appear in the post preview and i'm not sure how to collapse it.
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I'm not buying it. I don't think the human race has the potential to move water in a manner where it would affect the spin of the earth in any significant manner.
Significant? Probably not. But measurable? Yeah! 80 centimeters is infinitesimal on the scale of the entire planet. Personally, though, I think that's cool as hell that we're able to detect that small of a shift.
I mean, the research is right there if you want to confirm it yourself. Extraordinary claims require extraordinary evidence, but they have it.
There was no evidence presented, just a calculation that bridged a gap and one that I am unsure if it's even right given all the forces in the universe that can affect a planetoid. I've no idea whether or not it accounts for the volume of space junk in orbit or how that acts as a sink to slow us down. It doesn't even mention the moon or where it was. Still not buying it.
I didn't actually read it, but it's AGU which is kind of a big deal. If Earth science academics got this Earth science wrong that is itself extraordinary.
I'm reading it now. Do you understand it all? It looks like they're using spherical harmonics to approximate the contributions of each water shift to the drift of the rotational pole, which I sort of get but don't really.
Define "significant." Very large dammed reservoirs have an effect on the earth's spin. Think of it like an ice skater twirling. When her arms are out she spins slowly. When she pulls them close she spins faster. Angular momentum is preserved but the distribution of mass changes the angular velocity.
The discussion section of the paper is an interesting read (https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023GL103509). While I am not in a position to critique the authors' conclusions, they seem to indicate that their work is confirming other estimates of ground water depletion. So, I believe this is more about showing that previous estimates of 2,150 GTons of ground water depletion are plausible. They state that "neglecting groundwater depletion in the PM excitation budget leads to a trend that is more westward than observed."
In other words, they show that the amount of ground water depletion estimates by some climate models would be expected to have the same effect on polar motion that they have observed. Their paper doesn't specifically address whether this depletion is anthropogenic--that is an assertion made by the models they are testing through their observations.