About 2 billion people live with water scarcity around the world. Only about 1% of Earth’s water is usable, and only half that number is freshwater. India is one of the world’s largest producers of agricultural produce, and a large portion of that production relies on groundwater. Unfortunately, the rate at which water is being pumped from India’s aquifers is causing them to deplete rapidly. This has already resulted in a significant loss of agricultural output, especially for wheat and rice. This may lead to declining household food security and increased poverty and malnutrition. The good news is that solutions require a serious commitment to the issue.
While most of the water on Earth is in lakes, rivers, and oceans, much of it lies under the planet’s surface in aquifers. While this water is generally not saline, it does contain dissolved salts and other minerals. And while most of the world’s aquifers are contaminated with some pollution, it is still an essential water source for many communities.
Because of its oblate shape, the Earth wobbles on its axis as it spins. This is primarily caused by the uneven distribution of the planet’s mass, with heavier areas like mountains and ocean trenches adding to the weight that causes the wobble. The new study published in Geophysical Research Letters found that humans have pumped so much water out of the ground that it has effectively affected the planet’s spin. That is because redistributing the planet’s water has changed its mass, and the poles are moving.
Scientists looked at a wide range of factors to determine what was causing the polar shifts. They found that while natural forces like sloshing molten iron in the Earth’s core, melting ice, and ocean currents could also cause the shifts, the redistribution of groundwater had the most significant impact.
In the 17 years between 1993 and 2010, humanity pumped 2150 gigatons of water from Earth’s aquifers. This is enough to have shifted the weight of the Earth significantly and tipped the polar drift in a way similar to putting more weight on a spinning top, making it move differently. The researchers found that dams and the shifting of ice were not enough to match the observed polar drift – only when groundwater was included did the models align with observations.
While the slight polar drift won’t change the seasons or even affect the location of the continents, the scientists behind this study warn that over geological timescales, it could have significant impacts on climate. They also point out that a quick fix would be to reverse the direction of groundwater pumping. But that will be challenging given the rate at which water is being pulled from aquifers. This is especially important in India, where aquifers are pumped at very high rates. It is estimated that India will have critically low groundwater availability by 2025.