Scientists know the effect of underground reservoirs on maintaining Earth's balance. Geophysicist Ki-Weon Seo has discovered that humans have extracted so much groundwater from under our feet that the tilt of Earth's axis has changed. This shift has been big enough to relocate the North Pole. The mass of polar ice is drifting by more than four centimetres a year. Professor Seo calculated that we extracted more than two trillion tons of groundwater between 1993 and 2010. This caused Earth to wobble. Seo said the pumping of groundwater has caused sea levels to rise by 6.24 millimetres.

Professor Seo explained that groundwater affects gravity. He said: "Every mass moving around on the surface of the Earth can change the rotation axis." Scientists have recently found out how groundwater affects Earth's axis. They previously thought water-driven shifts were caused by melting glaciers. Seo was puzzled at how this could cause a tilt. He concluded that extracting underground water was also a factor. Much of the extraction of groundwater is due to irrigation. Another researcher said: "The very way the planet wobbles is impacted by our activities."