We’ve Pumped So Much Groundwater We’ve Caused a Pole Shift – Digital Journal

Many Americans rely on groundwater sources for their drinking water. Credit _ Environmental Protection Agency, State Dpmain

Sea level rise due to groundwater withdrawal has caused the Earth’s pole of rotation to drift by nearly a meter over two decades.

By pumping water out of the ground and moving it elsewhere, humans have moved so much water that the Earth tilted nearly 80 centimeters (31.5 inches) to the east between 1993 and 2010 alone, according to a new study published in 2010. Geophysical Research Letters.

For years, scientists have been aware of a gentle movement south of the planet’s axis of rotation, the imaginary rod around which it spins. So, the longest movement took place from the geographic North Pole to Canada. However, it suddenly made a sharp turn and started heading east, according to the New York Times.

In 2019, the Digital Journal reported a study showing that the Earth’s magnetic pole is moving about 50 km (30 mi) per year, a rapid increase since the 1980s. At the time, it was thought that the magnetic north shift was caused by a high-velocity jet of liquid iron in the Earth’s outer core beneath Canada.

But almost forgotten and yet very important was a study published in 2013 in the journal Geophysical Research Letters. The researchers found that the accelerated melting of polar and mountain glaciers has changed the distribution of mass across the planet enough to affect its spin on its axis of rotation.

Further research has led some of the same scientists to identify another factor that has the same effect: the huge amount of water being pumped out of the ground for crops and households.

Based on climate models, scientists previously estimated that between 1993 and 2010, humans pumped 2,150 gigatons of groundwater, equivalent to more than 6 millimeters (0.24 inches) of sea-level rise. But confirming this assessment is difficult.

The researchers found that the distribution of water on the planet affects the distribution of mass. Like adding a tiny bit of weight to a spinning surface, the Earth spins a little differently when water is displaced, Science Daily reports.

“The Earth’s pole of rotation is actually changing a lot,” said Ki-Weon Seo, a geophysicist at Seoul National University who led the study. “Our study shows that among climate-related causes, groundwater redistribution actually has the greatest impact on the rotation pole shift.”

“I’m not surprised that it would have an effect” on Earth’s rotation, said Matthew Rodel, an earth scientist at NASA’s Goddard Space Flight Center. But “it’s impressive that they were able to pull it out of the data, and that their observations of polar motion are accurate enough to see this effect.”

The Blue Marble’ is a famous photograph of Earth taken on December 7, 1972 by the crew of the Apollo 17 spacecraft en route to the Moon at a distance of approximately 29,000 kilometers (18,000 miles). Credit – (NASA) under Photo ID: AS17-148-22727, Public Domain

Human activity and global climate are factors

You can’t feel it, but our planet’s rotation is nowhere near as steady as the globe on your desk. But if you really think about it, as the Earth moves through space, it’s like a poorly thrown Frisbee.

This is partly because it bulges at the equator and partly because air masses are constantly swirling in the atmosphere and water is splashing across the oceans, pulling the planet ever so slightly this way and that.

And we also have to remember that the Earth’s crust and mantle are rebounding after thousands of years of being covered by gigantic sheets of ice that bounce like an air mattress after a human disembarks.

But the biggest changes have been caused by human activity. These include the melting of mountain glaciers and Greenland and Antarctic ice, changes in soil moisture, depletion of groundwater and the impoundment of our water behind dams.

The location of the groundwater plays a role in how much it could change the polar drift; the redistribution of water from the midlatitudes has a greater effect on the pole of rotation. During the study period, most of the water was redistributed to western North America and northwestern India, both mid-latitudes.

Attempts by countries to slow the rate of groundwater depletion, especially in these sensitive regions, could theoretically reverse the drift, but only if such conservation approaches are sustained over decades, Seo said.

“I am very happy to have discovered the unexplained cause of rotation pole misalignment,” Seo said. “On the other hand, as an Earthling and father, I am concerned and surprised to see groundwater pumping as another source of sea level rise.”

“Observing changes in the Earth’s rotation pole is useful for understanding continental-scale variations in water storage,” Seo said. “Polar movement data has been available since the end of the 19th yearth century. So, we can use this data to understand the variation in continental water storage over the past 100 years. Have there been any changes in the hydrological regime due to climate warming? Polar motion could provide the answer.

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