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be discover extract change be relocate drift calculate cause rise
affect move change discover believe cause be conclude be wobble
Perhaps it's only geophysicists who aware of the importance of underground reservoirs on maintaining Earth's balance. Geophysicist Ki-Weon Seo from Seoul National University has that humans have so much groundwater from under our feet that they have the tilt of Earth's axis. This shift has significant enough to physically the geographic North Pole. The mass of polar ice is by 4.36 centimetres a year. Professor Seo that we extracted more than two trillion tons of groundwater between 1993 and 2010, Earth to wobble. Seo added that the pumping of groundwater has caused sea levels to by 6.24 millimetres.

Professor Seo explained how groundwater Earth's gravity. He said: "Every mass around on the surface of the Earth can the rotation axis." Scientists have only recently how groundwater can change Earth's axis. They previously water-driven shifts were by melting glaciers and ice caps. Seo and his colleagues puzzled at how this could cause such a tilt. They that the depletion of underground water was also a factor. Much of the extraction of groundwater due to irrigation, especially in north-western India and western North America. Another researcher said: "The very way the planet is impacted by our activities."

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