Below the Earth’s surface lies over a thousand times more water than all the rivers and lakes in the world.
This groundwater accounts for almost all the freshwater on the planet.
But in many areas of the world, groundwater is being extracted faster than the rate that it naturally recharges.
A recent study found that humans are pumping so much groundwater that it’s not only increasing sea levels, it’s actually shifting the entire planet on its axis.
How groundwater depletion affects Earth’s rotational pole
The Earth’s rotational pole normally changes and wanders by about several meters each year.
Extracting groundwater also redistributes water mass. Groundwater naturally exists under continents, but about 80% finds its way to the ocean through rivers after extraction, therefore shifting all that water mass from Earth’s continents to its oceans.
And we’ve been extracting so much groundwater that it caused the Earth’s rotational pole to drift by 64. 16 degrees east at about 4. 36 centimeters per year from 1993 to 2010, researchers reported in the journal Geophysical Research Letters in June.
For comparison, a different study reported that the accelerated melting of the glaciers drove a polar drift of 26 degrees east at about 3. 28 milliarcseconds (or about 9. 84 centimeters) per year after the 1990s.
Since Earth’s rotational pole periodically wanders by several meters per year, this contribution of a few centimeters from groundwater depletion is unconcerning, one of the researchers told Insider.
“What we found in this study about drift of the pole would be negligible compared with such several meters oscillations. So, at this point, we wouldn’t worry about it,” said Ki-Weon Seo, geophysicist and associate professor in the Department of Earth Science Education at Seoul National University, who led the study. He also added that rotational poles return to their previous positions the majority of the time.
However, the contribution of groundwater to rising sea levels is something that is alarming.
Why humans pump so much groundwater and its negative effects on the Earth
To put it simply, groundwater depletion contributes to sea level rise because water is being transferred from the continents to the oceans.
The recent study found that groundwater depletion caused a 6. 24-millimeter rise in global sea level from 1993 to 2010. This is significant because each millimeter rise in sea level is said to make the shoreline retreat an average of 1. 5 meters.
Pumping too much groundwater too quickly can also decrease water flow from natural streams, another study found. When groundwater is pumped out by humans, the flow of water in streams can be reduced or stopped.
This in turn threatens many ecosystems which rely on the flow of water both within and around streams.
Without better management, an estimated 42% to 79% of all watersheds that pump groundwater may no longer be able to maintain healthy ecosystems by 2050.