Groundwater is stored under land but, once pumped up for drinking or agriculture, most eventually flows to sea, redistributing its weight around the world. The research, published in the journal Geophysical Research Letters, showed glacial losses accounted for most of the shift, but it is likely that the pumping up of groundwater also contributed to the movements. But Deng’s research breaks new ground by extending the link to before the satellite’s launch, showing human activities have been shifting the poles since the 1990s, almost three decades ago. Gravity data from the Grace satellite, launched in 2002, had been used to link glacial melting to movements of the pole in 20, both following increases in ice losses.
“The accelerated decline resulting from glacial ice melting is the main driver of the rapid polar drift after the 1990s,” concluded the team, led by Shanshan Deng, from the Institute of Geographic Sciences and Natural Resources Research at the Chinese Academy of Sciences. Since 1980, the position of the poles has moved about 4 metres in distance. The scientists found the direction of polar drift shifted from southward to eastward in 1995 and that the average speed of drift from 1995 to 2020 was 17 times faster than from 1981 to 1995. But the new research shows that since the 1990s, the loss of hundreds of billions of tonnes of ice a year into the oceans resulting from the climate crisis has caused the poles to move in new directions. In the past, only natural factors such as ocean currents and the convection of hot rock in the deep Earth contributed to the drifting position of the poles.