A study has found that humans are to blame for the Earth tilting more than 2.5 feet in 17 years. The research published in Geophysical Research Letters sought to explain a 31.5-inch shift in Earth's rotational tilt observed between 1993 and 2010. Researchers initially expected to account for the shift by considering the movement of water from ice sheets and glaciers. But those calculations only accounted for a half-inch shift, per USA Today.
"Our study shows that among climate-related causes, the redistribution of groundwater actually has the largest impact on the drift of the rotational pole," says study author Ki-Weon Seo, a geophysicist at Seoul National University, per Earth.com. According to the study's climate model estimate, some 2,150 gigatons of groundwater had to have been pumped out of aquifers between 1993 and 2010. To put that in perspective, one gigaton is equivalent to the total weight of all people on Earth multiplied by three, per USA Today. "We may not think about where our water goes after we use it, but most of it ends up being transported to the oceans," per Earth.com.
The redistribution not only caused the Earth's rotational pole to shift 31.5 inches to the east, "toward 64.16°E," but raised global sea levels by a quarter of an inch, according to the study. "I'm very glad to find the unexplained cause of the rotation pole drift," Seo tells Earth.com. "On the other hand, as a resident of Earth and a father, I'm concerned and surprised that pumping groundwater is another source of sea-level rise." Beyond that, Earth's greater tilt could impact climate, according to Surendra Adhikari, a research scientist at NASA's Jet Propulsion Laboratory. The study came out in June 2023 but has gotten renewed attention this week. (More groundwater stories.)