The End is Near: Earth's Rotation Begins to Shift

The depletion of massive amounts of groundwater reserves is not only impacting the environment but is also affecting the movement of planet Earth. Recent research findings show that during the 2000-2002 period, landmasses lost more than 1,600 gigatonnes of water previously stored beneath the surface. This loss of water volume on a massive scale has caused changes in Earth’s mass distribution, thereby triggering a shift in the planet’s rotation.

Researchers estimate that the position of Earth’s rotational axis has shifted by approximately 45 cm, with changes in water reserves being the dominant factor behind this phenomenon. Professor Clark Wilson, a geophysicist from the University of Texas at Austin and one of the study’s authors, explained that the movement of water from land to the oceans changes Earth’s moment of inertia, causing the planet’s axis of rotation to shift. “If you take a large amount of water from the land and move it to the ocean, you are redistributing mass across the planet,” Wilson stated, as quoted from Science Focus.

The research, led by Professor Ki-Weon Seo of Seoul National University, utilised a combination of satellite radar data and soil moisture models to reconstruct changes in global water deposits since the end of the 20th century. The findings indicate that between 2000 and 2002, there was a sharp decline in soil moisture, contributing to a global sea-level rise of approximately 1.95 mm per year, far exceeding the contribution from Greenland’s ice melt, which was only about 0.8 mm per year.

This drying trend has not ceased. From 2003 to 2016, an additional 1,000 gigatonnes of groundwater were lost. As of 2021, soil moisture levels have not returned to normal, indicating a long-term shift in terrestrial water storage. This shift in Earth’s axis coincides with regions experiencing extreme drought, including East and Central Asia, North and South America, and Central Africa. Wilson added that although this shift appears small, precise measurement is crucial, as it impacts the accuracy of GPS systems worldwide. Consequently, the movement of Earth’s axis continues to be monitored with millimetre-level precision.