Due to extensive groundwater extraction, our actions have inadvertently influenced the rotation of the Earth. The research team matched the observed polar drift to their model only after including 2150 gigatons of groundwater redistribution
The Earth’s rotational pole has wandered nearly a meter in two decades, with mass shifts and sea level rise caused by groundwater extraction playing a critical role, according to a new study. According to experts, groundwater withdrawal has tilted the Earth.
An unprecedented mass of water was relocated by human activity, tilting the Earth almost 80 centimeters east between 1993 and 2010, discloses the recent study published in the Geophysical Research Letters. Previous estimates from climate models suggested that from 1993 to 2010, humans extracted about 2,150 gigatons of groundwater, leading to a sea level rise of over 6 millimeters. But proving these estimates remains a challenge.
Groundwater Withdrawal Tilted Earth
The Earth’s rotational pole—the point around which the planet spins—shifts due to a process called polar motion, influenced by the distribution of water on Earth. The redistribution of groundwater is found to have the most substantial impact on the pole’s drift.
According to Ki-Weon Seo, the geophysicist leading the study, the potential of water to alter Earth’s rotation was discovered in 2016. But the specific contribution of groundwater to these changes remained unknown until now.
Modeling Effect on Polar Drift
The research team matched the observed polar drift to their model only after including 2150 gigatons of groundwater redistribution. Without it, the model fell short by 78.5 centimeters per year. Seo expresses both relief at uncovering the cause of the pole’s drift and concern about the implications of groundwater pumping on sea-level rise. Surendra Adhikari, an independent research scientist, confirms the study’s significance, underlining the notable impact of groundwater pumping on polar motion.
The Role of Groundwater Location
The impact of groundwater on polar drift is determined by its location. Water redistributed from the midlatitudes significantly affects the rotational pole, with western North America and northwestern India noted as key regions. Measures to decrease groundwater depletion could alter the drift, but only with sustained efforts over decades. While changes due to groundwater extraction don’t threaten seasonal shifts, they could potentially impact climate over geologic time, Adhikari suggests.
Seo suggests that studying past changes in Earth’s rotational pole could provide insights into historical water storage variations and how a warming climate might have affected hydrological regimes.