By pumping water out of the ground and moving it somewhere else, we have shifted a large mass of water that the earth has shifted nearly 80 centimeters to 31.5 inches. Mostly between the years 1993 and 2010. Our approach revolves around earth’s rotational pole, around which our planet rotates.
It rotates due to a process called Polar Motion, it’s a situation where earth’s rotational pole varies relative to the crust. Distribution of water on the planet affects how mass is distributed, for example adding a tiny bit of weight to the spinning top, the earth spins a bit differently as the water moves around.
According to scientists humans have pumped 2.150 gigatons of groundwater. Equivalent to 6 millimeters (0,24 inches) of sea level rise. According to Ki-Weon Sea, a geophysicist at Seoul National University,“ earth rotational pole actually changes a lot, our study shows that among climate related causes, the redistribution of groundwater actually has the largest impact on the drift of the rotational pole”.
In 2016 scientists discovered water’s ability to change the earth’s rotation, until then these rotational changes were unexplored. Researchers observed changes in the drift of Earth’s rotational pole and the movement of water. At first it was only ice sheets and glaciers that drifted the earth; later they found out that it also happens during groundwater redistribution.
According to their researchers the model of the earth drifted by 78.5 centimeters that’ 31 inches but adding 2150 gigatons of groundwater redistribution it drifted more.
“I am very glad to find the unexplained cause of the rotation pole drift, but on the other hand as a resident of earth and a father, i am concerned and surprised to find the pumping groundwater is another source of sea level rise”, says Seo.
According to Surendra Adhikari who is a research scientist at Jet propulsion laboratory , this is a nice contribution and important documentation for sure. He published in 2016 a documented research paper on water redistribution impacting on rotational drift. He says, “ they’ve quantified the role of groundwater pumping on polar motion that’s too pretty significant”.
Not only the location of groundwater matters but redistribution of water from the mid-attitudes has a larger impact. During a study it was found that the most water was redistributed in western North America and north western India. Both are at mid-attitudes.
According to Seo, Countries are trying to slow the groundwater depletion rates, specially in sensitive regions, that could alter the changes in drift, if only such conservation habits are sustained for decades.
“The rotational pole normally changes by several meters within about a year, so changes can occur due to groundwater pumping but they don’t run the risk of shifting seasons” ,says Adhikari.
“Observing changes in Earth’s rotational pole is useful for understanding continent scale water storage variation,” Seo said.
“Polar motion data are available from as early as the late 19th century, so we can potentially use those data to understand continental water storage variation during the last 100 years. Were there any hydrological regime changes resulting from the warming climate? Polar motion could hold the answer…