A sudden zag in which the North Pole was adrift in the 1990s probably resulted in much of the glacial melting caused by climate change, a new study suggests.
The locations of the Earth's geographic poles, where the planet's axis crosses the surface, are not fixed. On the contrary, they roam in seasonal and almost annual cycles, largely driven by meteorological patterns and ocean currents (SN: 15/04/03). But in addition to moving in relatively tight eddies only a few meters in diameter, the poles drift over time as the weight distribution of the planet changes and alters its rotation around its axis.
Prior to the mid-1990s, the North Pole was adrift toward the western edge of Canada’s Ellesmere Island. But then the pole turned east about 71 degrees toward the northeastern tip of Greenland. He continued to drive that way, moving about 10 inches a year. Scientists are not quite sure why this change occurred, says Suxia Liu, a hydrologist at the Beijing Institute of Geographical Sciences and Natural Resources Research.
Liu and colleagues have verified how well polar drift trends matched data from previous studies on glacial melting around the world. In particular, the melting of glaciers in Alaska, Greenland, and the Southern Andes accelerated in the 1990s (SN: 30/09/20). The timing of that thaw, as well as the effects it would have had on the Earth's mass distribution, suggests that climate change-induced glacial melting helped trigger the change in polar drift, the team said in its April 16 geophysical research chart. .
Team analysis shows that while the melting of glaciers may explain much of the change in polar drift, it does not explain everything. Therefore, other factors must be played. With abundant irrigation, for example, groundwater pumped from aquifers in a region can end up in a distant ocean (SN: 10/9/19). Like glacier melting, water management alone cannot explain the North Pole’s impact, the team reports, but it can give a substantial axis to the Earth’s axis.
The findings “reveal how much human activity can have an impact on changes in the mass of water stored on earth,” says Vincent Humphrey, a climate scientist at the University of Zurich who is not involved in this study. And they show how big these massive displacements can be, he says. "They're so big they can change the Earth's axis."