Ground Water Extraction Affecting Earth’s Spin on its Axis
A new study came into the news, showing that extraction of groundwater from the earth is affecting its rotation on its axis. Yes, a study published in Geophysical Research Letters on Advancing Earth and Space Science revealed that humans’ thirst to pump out fresh water from the underground surface of the earth has tilted its axis approx 80 centimetres (31.5 inches).
The study says, between the years 1993 and 2010, humans extracted 2,150 gigatons of groundwater from the earth. This amount is equivalent to a sea level rise of more than 6 millimetres (0.24 inches). And the study shows the redistribution of groundwater actually has the largest impact on the drift of the rotational pole of the earth.
Groundwater Distribution vs Earth’s Rotational Pole
As per the discoveries by the scientists, the Earth’s rotational pole, serves as the central point around which the planet rotates. This pole undergoes a process known as polar motion, where its position relative to the Earth’s crust varies.
Here the distribution of water across the planet plays a crucial role in altering the distribution of mass. Similar to how adding a small weight affects the spinning motion of a top, the movement of water has an impact on the Earth’s rotation.
As per the geophysicist from Seoul National University, Mr Ki-Weon Seo, who headed the research, the Earth’s rotational pole has undergone significant changes.
He emphasized that their study reveals how the redistribution of groundwater holds the most significant influence on the shifting of the rotational pole among various climate-related factors.
How Movement of Water Affecting Earth’s Rotational Pole?
The location of the groundwater matters for how much it could change polar drift; redistributing water from the midlatitudes has a larger impact on the rotational pole. During the study period, most water was redistributed in western North America and northwestern India, both at mid-latitudes.
Countries’ attempts to slow groundwater depletion rates, especially in those sensitive regions, could theoretically alter the change in drift, but only if such conservation approaches are sustained for decades, Seo said.
The rotational pole normally changes by several meters within about a year, so changes due to groundwater pumping don’t run the risk of shifting seasons. But on geologic time scales, polar drift can have an impact on climate, Adhikari said
In 2016, researchers uncovered the impact of water on the Earth’s rotation. However, until recently, the specific role played by groundwater in these rotational changes remained unexplored.
In this new study, scientists delved into this topic by constructing models to understand the observed shifts in the Earth’s rotational pole and the movement of water.
Initially, they focused solely on ice sheets and glaciers and later introduced various scenarios of groundwater redistribution into their analysis.
The researchers discovered that their model matched the observed polar drift only when they included 2,150 gigatons of groundwater redistribution. Without considering this factor, the model deviated by 78.5 centimetres (31 inches), equivalent to an annual drift of 4.3 centimetres (1.7 inches).
Seo expressed his delight at uncovering the previously unexplained reason behind the drift of the rotation pole. However, as someone who resides on Earth and a parent, he conveyed a mix of concern and surprise upon realizing that the pumping of groundwater serves as an additional contributor to the rise in sea levels.
While on tghe other hand, Surendra Adhikari, a research scientist at the Jet Propulsion Laboratory who did not participate in this study, commended the findings, describing them as a valuable contribution and an important record of information.
Adhikari, who authored a paper in 2016 exploring the influence of water redistribution on the rotational drift, acknowledged the significance of the researchers’ achievement in quantifying the impact of groundwater pumping on polar motion.
Source: Greek Reporter
