Study shows groundwater pumping tilts Earth’s spin, may affect climate

New Delhi: A study found that the Earth tilted about 80 cm east between 1993 and 2010 alone due to groundwater extraction, which may affect the temperature of our planet. According to the study, which was published in the journal Geophysical Research Letters, the areas of western North America and northwest India experienced the most water redistribution over the study period.

Scientists have previously estimated humans pumped 2,150 gigatons of groundwater, equivalent to more than 6 millimetres of sea level rise, from 1993 to 2010. However, validating that estimate is difficult.

The researchers noted that water’s ability to change the Earth’s rotation was discovered in 2016, and until now, the specific contribution of groundwater to these rotational changes was unexplored.

The latest study modelled the observed changes in the drift of Earth’s rotational pole and the movement of water—first, with only ice sheets and glaciers considered, and then adding in different scenarios of groundwater redistribution.

The model only matched the observed polar drift once the researchers included 2150 gigatons of groundwater redistribution. Without it, the model was off by 78.5 centimetres or 4.3 centimetres of drift per year.

The researchers said attempts by countries 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.

The rotational pole normally changes by several metres within about a year, so changes due to groundwater pumping do not run the risk of shifting seasons. However, on geologic time scales, polar drift can have an impact on climate, they said.

Mr Adhikari published the 2016 paper on water redistribution impacting rotational drift.

With PTI inputs