Using satellite data on how water moves around Earth, NASA scientists solved two mysteries about wobbles in the planet’s rotation. Earth’s spin axis drifts slowly around the poles; the farthest away it has wobbled since observations began is 37 feet (12 meters). These wobbles don’t affect daily life, but they must be taken into account to get accurate results from GPS, Earth-observing satellites and ground-based observatories.
In a paper published in Science Advances, researchers found that the loss of mass from Greenland and Antarctica’s rapidly melting ice sheet alone don’t generate the amount of energy needed to pull the spin axis as far as it has shifted.
“The bulk of the answer is a deficit of water in Eurasia: the Indian subcontinent and the Caspian Sea area,” said Surendra Adhikari of NASA’s Jet Propulsion Laboratory.
Although this region has lost much less water mass due to depletion of aquifers and drought than in the ice sheets, the spin axis is very sensitive to changes occurring around 45 degrees latitude, both north and south.
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