Earth Poles are Tipping Because of Climate Change

Climate Change, Anthropocene, & Associated Issues

Date posted: 04/11/16

Shannon Hall reports that the north pole is on the run. Although it can drift as much as 10 meters across a century, sometimes returning to near its origin, it has recently taken a sharp turn to the east. Climate change is the likely culprit, yet scientists are debating how much melting ice or changing rain patterns affect the pole wanderlust. The geographical poles, the north and south tips of the axis that the Earth spins around wobble over time due to small variations in the sun and moon pulls, and potentially to motion in Earth core and mantle. But changes on the planet surface can alter the poles, too. They wobble with every season as the distribution of snow and rain change, and over long stretches as well. Roughly 10,000 years ago, for example, Earth woke up from a deep freeze and the massive ice sheets sitting atop what is now Canada melted. As ice mass fled, and the depressed crust rebounded, the distribution of the planet mass changed and the north pole started to drift west. This pattern can be clearly seen in data from 1899 onward. But a recent zigzag in the north pole path (and the opposite movement in the south pole) suggests a new change is afoot. Around 2000, the pole took an eastward turn. It stopped drifting toward Hudson Bay, Canada, and started drifting along the Greenwich meridian in the direction of London. In 2013, Jianli Chen, a geophysicist at The University of Texas at Austin, was the first to attribute the sudden change to accelerated melting of the Greenland Ice Sheet. The result startled his team. If you are losing enough mass to change the orientation of the Earth that is a lot of mass, says John Ries, a Chen colleague at U.T. Austin. The team found that recent accelerated ice loss and associated sea-level rise accounted for more than 90% of the latest polar shift. Of course that includes ice lost across the world, but Greenland represents most of the mass loss. That is what is causing the pole to migrate. Read on.