Earth Has a Gravity Hole Under Antarctica

Here's something most people don't know: gravity isn't the same everywhere. It varies across Earth's surface based on what's underground, specifically the density of rock far below in the mantle, the hot layer between Earth's crust and core. Where the rock is less dense, gravity pulls a little weaker. And the weakest spot on the entire planet is directly beneath Antarctica.

This "gravity hole," known as the Antarctic Geoid Low, has a real, measurable effect on the ocean. Gravity pulls water toward it, so where gravity is weaker, water flows away. The sea surface around Antarctica actually sits lower than it would without this effect. The planet's own uneven gravity is reshaping its oceans.

Researchers at the University of Florida and the Paris Institute of Earth Physics used earthquake waves to reconstruct how this gravity hole formed and changed over 70 million years. Every major earthquake sends vibrations through the entire Earth, and scientists used those waves like a planetary CT scan to see the rock structures deep inside. The gravity hole has been present since the age of the dinosaurs, but intensified significantly between 50 and 30 million years ago, driven by slow movements of hot and cold rock deep in the mantle.

Here's where it gets stranger: that intensification happened at almost exactly the same time Antarctica's climate shifted and its massive ice sheets began to form. Whether the deepening gravity hole helped cause that glaciation, or whether both were driven by the same deep-Earth processes, is the question researchers are now building toward.

Something has been shifting deep under Antarctica for 50 million years. The ice sheets above it may be the only evidence we can see.

Read the full story at University of Florida, February 13, 2026

Hot Take: The planet has been quietly rearranging its own gravitational architecture for 50 million years in ways that may have built the ice sheets that stabilize global climate, and the fact that we needed a CT scan made of earthquakes to figure that out is not a limitation of science. It's the whole point of it.