Groundwater Pumping Changes Earth’s Tilt, Research Shows

A recent study published in Geophysical Research Letters reveals that by pumping and relocating water from underground sources, humans have caused a significant shift in the Earth’s orientation.

Between the years 1993 and 2010, this activity led to a noteworthy eastward tilt of approximately 80 centimeters (31.5 inches).

Previously, scientists used climate models to approximate that humans extracted 2,150 gigatons of groundwater from 1993 to 2010. This amount is equivalent to a sea level rise of more than 6 millimeters (0.24 inches).

Understand by examining the Earth’s rotational pole

One way to investigate this phenomenon is by examining the Earth’s rotational pole, which 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.

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.

Ki-Weon Seo, a geophysicist from Seoul National University who headed the research, said that the Earth’s rotational pole has undergone significant changes.

Seo 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.

‘Drift of Earth’s rotational pole and the movement of water’

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 centimeters (31 inches), equivalent to an annual drift of 4.3 centimeters (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.

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 rotational drift, acknowledged the significance of the researchers’ achievement in quantifying the impact of groundwater pumping on the polar motion.