For nearly two decades, the Earth's axis of rotation has drifted by 80 centimeters. An anomaly which once again reveals the colossal impact of human activities on the balance of our planet.
A planet “unhinged” by our activities
A recent study published in Geophysical Research Letters reveals an alarming phenomenon: the massive redistribution of groundwater by human activities has destabilized the Earth's axis of rotation. Between 1993 and 2010, the extraction of 2,150 gigatons of water shifted the balance of our planet. This transfer caused an average annual deviation of 4.63 centimeters from the axis of rotation, or a total of 80 centimeters in less than twenty years.
To understand this phenomenon, the researchers, led by Ki-Weon Seo of Seoul National University, used mathematical simulations based on historical astronomical observations. The latter, which date back to 1899, make it possible to detect fluctuations in the earth's axis thanks to apparent variations in the constellations.
A global redistribution of water that weighs heavily
Scientists identify the main culprits of this “planetary scoliosis”: the intense water movements observed in certain specific regions, notably western North America and northwest India. These areas, subject to intensive exploitation of their groundwater, played a key role in this mass redistribution.
By moving huge volumes of water from land areas to the oceans, humanity is altering the Earth's natural balance, much like adding weight to a spinning top. Consequence? Not only is the axis of rotation changing, but sea level rise is accelerating. According to the South Korean model, this redistribution would have contributed to a rise in water levels of 6.24 millimeters, a figure which adds to the already known impacts of global warming.
A disruption with multiple consequences
Groundwater extraction is not the only human activity singled out. Other factors, such as melting ice and rising ocean levels, also contribute to these fluctuations, according to NASA. These disturbances explain approximately 90% of the variations in the Earth's axis. The remaining 10% is thought to be attributable to internal processes, including the tilt of the Earth's core, over which humanity has no direct influence – yet.
A wake-up call for our future
This shift in the earth's axis once again highlights the massive impact of humanity on its environment. While discussions around climate change and the depletion of natural resources are increasing, this discovery illustrates another dimension of our influence: the capacity to disrupt fundamental mechanisms which govern the balance of our planet.
Far from being trivial, these disturbances can have chain repercussions on ecosystems, weather and human habitats. This observation calls for more responsible management of water resources and global awareness to limit our footprint on the planet.
Sources :
- Seo, K.-W. et al. (2024). Geophysical Research Letters.
- NASA Earth Science Division, 2023.
- Popular Mechanics, 2024.
