As the Earth moves on a rotating pole, the distribution of water on the planet affects the distribution of its mass. “Just like adding a little bit of weight to a spinning top,” the authors say, “the Earth spins a little differently as the water moves.”

NASA research published in 2016 alerted us to the fact that the distribution of water can change the Earth’s rotation. This study in Geophysical research letters tries to add some hard figures to that realization. “I am very happy to have found the unexplained cause of the rotation pole deviation,” said Seo. “On the other hand, as an inhabitant of the Earth and as a father, I am concerned and surprised to see that groundwater pumping is another source of sea level rise.”

The study included data from 1993 through 2010 and showed that pumping as much as 2,150 gigatons of groundwater caused a change in the Earth’s slope of about 90 centimeters. The pumping is largely for irrigation and human use, ultimately moving groundwater to the oceans.

In the study, researchers modeled observed changes in the drift of Earth’s rotation pole and the movement of water. In several scenarios, the only model that matched the drift was one that included 2,150 gigatons of groundwater distribution.

Surendra Adhikari, a research scientist at NASA’s Jet Propulsion Laboratory who was involved in the 2016 study, says the additional research is important. “They have quantified the role of groundwater pumping on polar movement,” he said in a press release, “and it is quite significant.”

Where the water moves from and to is important. Redistributing water from the mid-latitudes makes the biggest difference, so our intense water movement from both western North America and northwestern India has played a key role in the tilt changes.

With the impact of water movements known for such a short time (and relatively recently), searching through historical data can help reveal trends and provide more depth in understanding the effects of groundwater movements.

“Observing changes in Earth’s rotation pole is useful,” says Seo, “for understanding variations in water storage at the continent scale.”

This data can also help conservationists understand how to work to avert continued sea level rise and other climate problems. Hopefully the changes can be implemented appropriately over time.

Tim Newcomb is a journalist based in the Pacific Northwest. He covers stadiums, sneakers, equipment, infrastructure and more for a variety of publications, including Popular Mechanics. His favorite interviews include sit-downs with Roger Federer in Switzerland, Kobe Bryant in Los Angeles and Tinker Hatfield in Portland.