If you've felt a bit off-balance, you can blame your fellow humans: The pumping of groundwater caused the Earth to tilt 31.5 inches over a 17-year period, or about 1.8 inches per year.
As reported in recent days by outlets including Popular Science and USA Today, the pumping of 2,150 gigatons of groundwater from 1993 to 2010 shifted the Earth's tilt more than two feet. (One gigaton of water represents about 2.2 trillion pounds of water, or a billion metric tons.) The research was originally published in the journal Geophysical Research Letters in June of last year.
Most of the groundwater pumping is for farming irrigation and the water we use for drinking, bathing and other domestic and industrial uses. Redistributing the water from its natural courses appears to be what causes the effect.
The Earth has always had a tilt to its axis of 23.5 degrees, which is why we have seasons and daylight saving time.
The pumped groundwater eventually makes its way to the oceans and has contributed, in a modest way, to rising sea levels. A more significant contributor to the rise in sea levels has been climate change stemming from the burning of fossil fuels, which has led to the melting of glaciers and sea ice. In both cases, it's human activity that's having an effect on the planet's water balance.
The research was led by Ki-Weon Seo of Seoul National University and follows up similar findings that date back to NASA from 2016.
"Earth's rotational pole actually changes a lot," Seo said in a statement when the research was published. "Our study shows that among climate-related causes, the redistribution of groundwater actually has the largest impact on the drift of the rotational pole."
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