Over the last two decades, Earth has tilted by an astonishing 31.5 inches, and scientists believe they have identified the primary cause. According to a study published in Geophysical Research Letters, the tilt is directly linked to the widespread extraction of groundwater, a human activity that has far-reaching consequences for our planet’s balance and rotation.
Understanding Earth’s Rotational Drift
Earth’s rotational pole is not fixed—it shifts naturally over time due to various factors. However, lead study author and geophysicist Ki-Weon Seo explains that the redistribution of groundwater has emerged as the most significant contributor to this phenomenon.
“Earth’s rotational pole actually changes a lot,” Seo noted. “Our study shows that among climate-related causes, the redistribution of groundwater actually has the largest impact on the drift of the rotational pole.”
The research examined data from 1993 to 2010 and found that pumping approximately 2,150 gigatons of groundwater during this period caused the planet to tilt by 31.5 inches.
The Role of Groundwater Pumping
Groundwater, which resides beneath the Earth’s surface in soil and rocks, is often used for purposes such as irrigation, mining, and consumption. This water gradually seeps into aquifers—rock formations that store water until it filters into springs or wells. However, when groundwater is extracted and ultimately flows into the oceans, it not only shifts Earth’s weight distribution but also contributes to rising sea levels.
The study found that the redistribution of this massive amount of water has led to a 0.24-inch rise in global sea levels—seemingly small but significant in the context of climate change.
“I’m very glad to find the unexplained cause of the rotation pole drift,” Seo remarked. “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.”
Areas Most Affected
Regions with high rates of groundwater extraction, such as parts of North America and northwestern India, are contributing disproportionately to this issue. As groundwater is pumped and redistributed globally, the resulting tilt and sea-level changes underscore the profound impact of human activity on the planet.
Surendra Adhikari, a researcher involved in a related NASA study from 2016, praised the findings, saying, “They’ve quantified the role of groundwater pumping on polar motion, and it’s pretty significant.”
Moving Forward
Scientists hope that understanding the effects of groundwater pumping will encourage strategies to mitigate its impact. “Observing changes in Earth’s rotational pole is useful for understanding continent-scale water storage variations,” Seo explained.
This research highlights the interconnectedness of human activity and Earth’s delicate systems, urging a closer examination of how we manage natural resources to ensure the planet’s long-term stability.