Melting Polar Ice Reshapes Earth, Scientists Find
The planet is becoming rounder as melting ice sheets in Greenland and Antarctica remove pressure from the Earth's crust.
Updated on Oct. 22, 2026 in Geography
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Between 2011 and 2015, researchers observed that the Earth's poles are rising and its equatorial bulge is shrinking by approximately 1 millimeter per year. This shift toward a rounder shape is driven by the redistribution of mass as polar ice sheets melt.
Why it matters
The redistribution of mass caused by melting ice removes significant pressure from the Earth's crust, which in turn influences the planet's rotational speed. Understanding these structural changes is essential for maintaining the precision of satellite-based navigation and global positioning systems.
The Earth's diameter at the equator is approximately 12,756 kilometers, with the planet becoming flatter by 0.8 millimeters per year when accounting for both the solid crust and global oceans. The rate of rounding is increasing by 0.4 millimeters per year each decade.
The details
The study utilized direct data from the Global Navigation Satellite System to monitor planetary shape changes alongside observations of the Earth's gravitational field. These mass redistribution effects also contribute to the long-term slowing of the Earth's rotation.
Timeline
Between 1997 and 2000, the Earth became rounder at a rate of 0.5 millimeters per year.
Between 2011 and 2015, the poles rose and the equatorial bulge shrank by 1 millimeter annually.
The Big Picture
This research utilizes the Global Navigation Satellite System to redefine our understanding of how mass redistribution alters the planet's physical form. It marks a departure from static models of Earth's geometry by demonstrating a quantifiable, ongoing shift in shape driven by ice loss.
While these shifts occur on a planetary scale, they impact the accuracy of global positioning technologies that millions of people rely on daily. Refined measurements help scientists and engineers maintain the precision of navigation systems as the planet continues to physically evolve.
The takeaway
The Earth is not a static sphere and responds dynamically to the loss of mass at its poles. These findings underscore the interconnected nature of global climate change and the physical stability of our planet.
Further reading
Learn more about planetary dynamics in our Geography section.
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Do you believe human actions are the primary driver of major changes to our planet's shape?
