The shifting of mass and consequent sea level rise due to groundwater withdrawal has caused the Earth’s rotational pole to wander nearly a meter in two decades
AMERICAN GEOPHYSICAL UNION
American Geophysical Union
15 June 2023
Release No. 23-25
For Immediate Release
This press release is available online at: https://news.agu.org/press-release/weve-pumped-so-much-groundwater-that-weve-nudged-the-earths-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 that the Earth tilted nearly 80 centimeters (31.5 inches) east between 1993 and 2010 alone, according to a new study published in Geophysical Research Letters, AGU’s journal for short-format, high-impact research with implications spanning the Earth and space sciences.
Based on climate models, scientists previously estimated humans pumped 2,150 gigatons of groundwater, equivalent to more than 6 millimeters (0.24 inches) of sea level rise, from 1993 to 2010. But validating that estimate is difficult.
One approach lies with the Earth’s rotational pole, which is the point around which the planet rotates. It moves during a process called polar motion, which is when the position of the Earth’s rotational pole varies relative to the crust. The distribution of water on the planet affects how mass is distributed. Like adding a tiny bit of weight to a spinning top, the Earth spins a little differently as water is moved around.
“Earth’s rotational pole actually changes a lot,” said Ki-Weon Seo, a geophysicist at Seoul National University who led the study. “Our study shows that among climate-related causes, the redistribution of groundwater actually has the largest impact on the drift of the rotational pole.”
Water’s ability to change the Earth’s rotation was discovered in 2016, and until now, the specific contribution of groundwater to these rotational changes was unexplored. In the new study, researchers modeled the observed changes in the drift of Earth’s rotational pole and the movement of water — first, with only ice sheets and glaciers considered, and then adding in different scenarios of groundwater redistribution.
The model only matched the observed polar drift once the researchers included 2150 gigatons of groundwater redistribution. Without it, the model was off by 78.5 centimeters (31 inches), or 4.3 centimeters (1.7 inches) of drift per year.
“I’m very glad to find the unexplained cause of the rotation pole drift,” Seo said. “On the other hand, as a resident of Earth and a father, I’m concerned and surprised to see that pumping groundwater is another source of sea-level rise.”
“This is a nice contribution and an important documentation for sure,” said Surendra Adhikari, a research scientist at the Jet Propulsion Laboratory who was not involved in this study. Adhikari published the 2016 paper on water redistribution impacting rotational drift. “They’ve quantified the role of groundwater pumping on polar motion, and it’s pretty significant.”
The location of the groundwater matters for how much it could change polar drift; redistributing water from the midlatitudes has a larger impact on the rotational pole. During the study period, the most water was redistributed in western North America and northwestern India, both at midlatitudes.
Countries’ attempts to slow groundwater depletion rates, especially in those sensitive regions, could theoretically alter the change in drift, but only if such conservation approaches are sustained for decades, Seo said.
The rotational pole normally changes by several meters within about a year, so changes due to groundwater pumping don’t run the risk of shifting seasons. But on geologic time scales, polar drift can have an impact on climate, Adhikari said.
The next step for this research could be looking to the past.
“Observing changes in Earth’s rotational pole is useful for understanding continent-scale water storage variations,” Seo said. “Polar motion data are available from as early as the late 19th century. So, we can potentially use those data to understand continental water storage variations during the last 100 years. Were there any hydrological regime changes resulting from the warming climate? Polar motion could hold the answer.”
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Notes for journalists:
This study is published in Geophysical Research Letters, a fully open-access journal. View and download a pdf of the study here.
Paper title:
“Drift of the Earth’s pole confirms groundwater depletion as a significant contributor to global sea level rise 1993-2010”
Authors:
- Ki-Weon Seo (corresponding author), Center for Educational Research and Department of Earth Science Education, Seoul National University, Seoul, Republic of Korea
- Jae-Seung Kim, Kookhyoun Youm, Department of Earth Science Education, Seoul National University, Seoul, Republic of Korea
- Dongryeol Ryu, Department of Infrastructure Engineering, The University of Melbourne, Parkville, Australia
- Jooyoung Eom, Department of Earth Science Education, Kyungpook National University, Daegu, Republic of Korea
- Taewhan Jeon, Center for Educational Research, Seoul National University, Seoul, Republic of Korea
- Jianli Chen, Department of Land Surveying and Geo-informatics, and Research Institute for Land and Space, Hong Kong Polytechnic University, Hong Kong
- Clark Wilson, Department of Geological Sciences, and Center for Space Research, University of Texas at Austin, Austin, TX, USA
JOURNAL
Geophysical Research Letters
DOI
ARTICLE TITLE
“Drift of the Earth’s pole confirms groundwater depletion as a significant contributor to global sea level rise 1993-2010”
ARTICLE PUBLICATION DATE
15-Jun-2023
“The shifting of mass and consequent sea level rise due to groundwater withdrawal has caused the Earth’s rotational pole to wander nearly a meter in two decades”
OMG, it’s a disaster! How will we survive the pole having moved that much? We gotta do something about this- and move it back! 🙂
God save the Queen!
ha, ha- yuh, Biden said that recently
Perhaps he was talking about his son’s boyfriend ?
“We gotta do something about this- and move it back”
Mountaintop removal coal mining to offset?
Ik is alway good to read the actual paper and not the press release https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023GL103509
What a crock of feces!!!
This study claims that groundwater pumping is “related to climate change”, which of course is preposterous. There is zero relationship between climate change and pumping of groundwater. There IS a relationship between climate and groundwater use, in the sense that groundwater “mining” is often but not always used when precipitation is reduced (ie desert areas). But groundwater is also frequently used over surface water sources due to pollution of surface water sources, or when flat topography makes surface reservoirs less feasible.
Secondly, their theory ignores the actual historic data that shows ice mass increasing in the polar glacial areas of the planet, not decreasing.
Thirdly, their study presumes that liquid water is somehow destroyed by groundwater consumption, which of course is bull honkey. The liquid water pumped from the ground is always returned to the ground, by way of return drainage to rivers from farm fields, discharges of treated wastewater to rivers, direct ground application (irrigation), and production of solid waste that either naturally biodegrades or is disposed under ground.
Any groundwater that evapotranspires from irrigation ends up only temporarily in the lower atmosphere, after which it precipitates back to the surface again somewhere downwind, possibly close by if a mountain range is downwind. In which case the water either ends up underground or running off and either ending in the ocean or gets recycled again.
The bottom line here is that all water beneficially used by humans is merely recycled and never destroyed.
And the earth’s axis has always moved about due to massive glaciation and interglacial events, erosion, plate tectonics and the movement of continental plates, and gravitational forces exerted on earth by the moon, sun, and planets in our solar system. It is unavoidable, natural, and of little to no consequence to humans or the environment.
It is obvious here that this study team went grant-fishing, and the surest means of winning grant funding is to claim a posited effect related to climate change.
And how many gigatons of solid material has been shifted from one location to another for things like building material, steel for cars and ships, etc. etc.?
AGU is another example of a so called professional scientific organization that has deteriorated into a gaggle of lemmings whoring for Fed grant monies. This is just sad.
Hey! When Leftist governments cast money far and wide what’s wrong with bending over to pick it up? All of that government money, however, has effectively stopped the advancement of science in the West. We’ll all just have to learn Mandarin and/or Hindi to keep up on scientific advances in the future.
A lot of things seem to be invented in USA after Y2K – like this web page? I do agree that the next generation of tech could come from other places, but as of now they seem to deploy their tech in the USA first.
Let’s do a little math here, with no fancy super computer necessary. Here is a very simple calculation that the study authors ignored:
The estimated worldwide withdrawal rate of groundwater is 92 cubic kilometers per year. That water is not destroyed or removed from the earth’s surface, but is merely moved around a little.
The study authors here ignored plate tectonics which moves the entire crust of the planet around in various directions and at varying rates, ranging from about 1-2 cm per year to 15 cm per year depending upon the plate. All geologists know this stuff quite well.
Now, just take one single tectonic plate, one of the smallest on the planet: the Indian plate, which is moving northward at a rate of 15 cm per year. The surface area of the Indian plate is 11.9 million square kilometers, while the average thickness (relatively thin compared to other tectonic plates) is 100 km. The volume of the Indian plate therefore is approximately 100 x 11.9 million km cubed, or 1.19 billion km cubed.
Using an average density ratio between silicaceous rock and liquid water of about 2.7 to one, then the mass of the Indian plate is approx.1.19 billion times 2.7 divided by 92, which is 349million times the mass of all the groundwater in the world! Just one small tectonic plate!
Given that rotational or angular momentum on a spherical surface is directly proportional to both mass and velocity, and the velocity of the Indian plate is 15 cm per year, and the velocity of changes in groundwater location on the earth’s surface per year has to be very small – it has to be less than 1cm per year – then it is quite obvious that the rotational momentum effect on the earth’s axis due to the movement of the world’s smallest continental plate is fantastically larger in magnitude than the rotational momentum effect of all of the world’s groundwater withdrawals even assuming that the groundwater somehow simply disappears from the planet, which is of course preposterous.
“is fantastically larger in magnitude than”
Tiny and nonexistent are not the same thing.
How can change in sealevel be the cause? Water is drawn from aquifers nearlt well above sealevel. So, for a start, even if you imagine this makes it to the sea, then the average mass of earth’s water is lower than it was before, not higher. Duh!
Now, looking deeper into the problem, much of this drawn water is taken up by crops and also evaporated into the air. The weight of the crops has shifted the average mass of the earth outwards. Since most crops dont need groundwater, rain does the job, then the mass shift outwards because of the weight of the crops isnt all wellwater.
Getting more complicated? Getting to the sea by rivers, some of this original wellwater is also withdrawn for irrigation downstream (more crops!) and town supply. Do you know that doing mass balances in a manufacturing plant or mine processing plant is generally done by a specialist. Takeaway: the researcher has it backwards.
The point is that the location of the oceans where the water ends up is not the same location as where it started. By changing altitude, the water will change the rotational energy of the earth, by a very tiny amount.
By changing it’s physical location, it affects the axis of rotation, also by a very tiny amount.
Nobody so far has mentioned spinning ice skaters pulling arms in and out, or mentioned twisted up school yard swing set chains. So sad.
In 2018 the US estimates there were 11.4 million illegal immigrants in the US.
(Of course a lot more have come since then!)
Assuming an average weight of 150 lbs. that would be a shift of about 845,000 tons.
Do they count?
“Based on climate models, . . .”
First sentence of second paragraph of AGU press release in above article.
Stopped reading right then and there.
Billions of tons of ice melt each year either at the north pole or south pole and then it is replaced months later. Some say it is not all replaced each year. Speaking in terms of a spinning ‘top’, that would seem to imbalance the top and bottom of the ‘top’ regularly.
How would pumping groundwater from under a small part of the land area compete with that? Especially since much of it is replaced by precip every year.
Not an answer, but related to the question: Angular momentum calculations involve radius, distance of a mass from the rotational axis. In the case you describe, the pole water has a large disadvantage relative to equator water.
They’d have better luck claiming dense urban development and dams have “nudged” Earth’s spin.
I suppose this theory could be correct, but as long of their estimate is based solely on making their model fit the observations, it is not a finding, but rather a theory. there may be other unexplained factors that play a major role.
Not even a theory, but a conjecture.
2,150 gigatons of groundwater, are 2.15E12 liter,
there are more than 7E9 people on this planet and the observed time span was 17 years,
So we are talking about less than 20l (about 5 gallons) per person per year, about an ounce per week. I would say the order of magnitude is about right, if not a bit low.
Your point is not clear to me.
next they’ll argue that you can spin faster with your arms across your chest
You would know all about “spin”…
It is what BEST hired you for.!
No, they are arguing that you spin faster if a hair fell out of your left nose. And just think what would happen to your spin if you bought a ball-tucking swimsuit at Target.
DF: I have actually not taken up biking because it seems to require spandex shorts that I don’t prefer. Men on bikes who wear loose running shorts have become anachronistic.
Others: “I don’t care what other people think.” Yeah, yah do. This is a _comment_section_.
All except the obligatory “worry about sea level rise” this is an interesting paper. I note that there was no mention of glacial rebound as a factor. The polar moment J2 has been declining for a long time, throughout the satellite era at least, and it is reasonably shown to be the result of rebound. Since rebound has a complex spatial pattern I wonder about its influence here.
I also wonder if this secular drift of the pole leads to an accumulation of errors in eclipse observations versus predictions? I also note that large scale irrigation tailwater travels in rivers down to the sea, there is also an enormous discharge of groundwater unseen and poorly known directly to the ocean above the continental shelf.
Lucky we’re not in Guam.
What a crock.
If true, how much did the Earths rotation change with each ice age as millions of tons of ice formed at each of the poles. How much has the Earths rotation changed as the crustal plates move in imperceptible ways, yet continue to form mountain ranges.
Where is the control group? All other factors (mining, recharging basins, etc.) would have to be controlled for. So this is not science.
Mining is an interesting idea. I wonder whether we dig deep enough for high-density, high-volume ore to cause a long term shift in mass distribution. In theory, every time we exhale we would cause a vanishingly small change in rotation.
“Does oil float to the top or bottom?
Because oil is less dense than water, it will always float on top of water, creating a surface layer of oil.”
I wonder has anyone asked them to model oil extraction? maybe it was a practice run.