In the year 2000, the Earth’s spin axis made a sudden turn towards the east. While some shifts in the geographical pole occur regularly and are well understood, this sudden shift required a new explanation. According to teams from UT Austin and NASA’s Jet Propulsion Laboratory (JPL), climate change is the driving force behind the north pole’s wayward path.
In 2013, the team from UT Austin proposed that the accelerated melting of ice sheets near Greenland is driving the north pole to the east. Two years later, collaborators at JPL have come forward with a slightly more nuanced solution. The sudden shift is due to a combination of melting ice sheets and the redistribution of water on land. The JPL team suggests a dry spell in Eurasia also exerts an eastward pull on the Earth’s axis.
The team from JPL also claims that these climate induced changes to the Earth’s terrestrial water supply solve another mystery: a periodic shift in the Earth’s spin axis that occurs roughly every 6-14 years. However, there are serious limitations to this claim. JPL only has access to data from the years 2003-2015. Even if the solution provided by JPL correctly explains the mysterious periodic signal, twelve years is not enough time to prove their theory conclusively. It is also impossible to say whether changes in the distribution of water on the Earth’s surface are from a climate induced response to carbon dioxide or natural variability.
Uncertainties aside, the announcement by JPL does point to an inextricable link between the Earth’s climate, water cycling, and the Earth’s axis of rotation. Researchers from UT Austin and JPL both plan to use this knowledge to help separate the effects of man-made climate change from natural variations in climate. One plan is to investigate historical records of the Earth’s axis of rotation, and use the data to infer further information about water cycling and climate development over time. In the meantime, scientists hope that their research can be used to highlight the large scale impacts of climate change.
Acknowledgments: Many thanks to Chris Horvat, a graduate student in Applied Mathematics at Harvard University for providing his expertise and commentary on the subject.
Climate-driven polar motion 2003-2015, as published in Science Advances.