Here’s what you’ll learn when you read this story: When humans pump groundwater, it has a substantial impact on the tilt of Earth’s rotation. Additionally, a study documents just how much of an influence groundwater pumping has on climate change. Understanding this relatively recent data may provide a better understanding of how to help stave off sea-level rise.
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**Water Has Power: Changing Earth’s Rotation and Climate**
Water holds immense power—so much so that pumping Earth’s groundwater can change the planet’s tilt and rotation. It also contributes to sea-level rise and other consequences of climate change. Recent research reveals that groundwater pumping has a greater impact than previously thought.
Thanks to a study published in the journal *Geophysical Research Letters*, we now know that in less than two decades, Earth has tilted approximately 31.5 inches due to groundwater pumping. This tilt equates to about 0.24 inches of sea-level rise.
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**Groundwater Pumping and Earth’s Rotational Pole Drift**
“Earth’s rotational pole actually changes a lot,” says Ki-Weon Seo, a geophysicist at Seoul National University and the study’s lead author. “Our study shows that among climate-related causes, the redistribution of groundwater actually has the largest impact on the drift of the rotational pole.”
As the Earth spins on its axis, the distribution of water across the planet impacts how mass is distributed. The authors of the study explain it as adding a tiny bit of weight to a spinning top: “The Earth spins a little differently as water is moved around.”
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**Building on NASA’s Earlier Research**
NASA research published in 2016 first alerted scientists to the fact that how water is distributed can alter Earth’s rotation. This recent study in *Geophysical Research Letters* adds precise figures to that understanding.
Seo shares, “I’m very glad to find the unexplained cause of the rotation pole drift. 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.”
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**The Study: Groundwater Pumping’s Impact in Numbers**
The study analyzed data from 1993 through 2010, revealing that pumping as much as 2,150 gigatons of groundwater caused Earth’s tilt to change by roughly 31.5 inches. This groundwater is mainly extracted for irrigation and human consumption, eventually making its way to the oceans.
Researchers modeled observed changes in Earth’s rotational pole and water movement. Importantly, the only model that accurately matched the pole’s drift incorporated the redistribution of 2,150 gigatons of groundwater.
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**Expert Insights: Quantifying the Role of Groundwater**
Surendra Adhikari, a research scientist at NASA’s Jet Propulsion Laboratory and part of the 2016 study, emphasizes the importance of this new research.
“They’ve quantified the role of groundwater pumping on polar motion,” he states. “And it’s pretty significant.”
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**Where Water Moves Matters**
The origin and destination of water movement significantly affect Earth’s rotation. Redistributing water from midlatitude regions causes the most substantial impact. Intense groundwater pumping in western North America and northwestern India has played key roles in the observed tilt changes.
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**Looking Forward: Historical Data and Continued Study**
Now that the influence of water movement on Earth’s rotation is known for this short and relatively recent period, examining historical data could reveal long-term trends. This deeper understanding may improve knowledge of groundwater movement effects and their broader implications.
“Observing changes in Earth’s rotational pole is useful,” Seo explains, “for understanding continent-scale water storage variations.”
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As we continue to uncover the powerful effects of groundwater pumping, it becomes increasingly clear that managing water resources wisely is crucial—not only for sustaining life but also for maintaining the planet’s stability.
https://www.popularmechanics.com/science/environment/a69445743/why-earth-has-tilted-scientific-reason/
