“Hole” under the continent helps explain ice evolution and sea level variations.
It may sound like science fiction, but it is a real phenomenon, rooted in geological processes that have been occurring within the Earth for tens of millions of years, since the time when dinosaurs still roamed the planet.
But calm down: it’s not the Apocalypse. This anomaly is actually on scientists’ side and becoming an important piece in understanding the history of the great Antarctic ice sheets and how they influence global climate.
Gravity is generally felt as a constant in everyday life, but it is not the same across the planet, says . Small differences in the distribution of masses and densities inside the Earth translate into variations in the gravitational field. In the mantle, the density of rocks is not uniform. These disparities, over time, influence the ocean: in areas where gravity is slightly weaker, the sea surface tends to be lower, because water flows towards regions of stronger gravitational attraction.
The most marked expression of this reduction occurs in the so-called Antarctic Geoid Low (AGL)sometimes described as the continent’s “gravity hole”.
According to a December 19 study in Scientific Reports, the key to reconstructing the origin and evolution of this anomaly lies in the seismic waves generated by earthquakes in the region.
The researchers turned to an approach that combines seismic data, geodynamics and mineral physics to produce a three-dimensional model of the Earth’s interior.
“It’s like taking a CT scan of the entire planet, but without X-rays: we use earthquakes,” he explained. Alessandro Fortea geophysicist at the University of Florida and co-author of the work, in a statement. Seismic waves work like a “light” that allows us to infer deep structures and flows in the mantle.
Based on this seismic “tomography,” the team compared the new map with satellite analysis and applied advanced computer modeling to “turn back” the geophysical clock to about 70 million yearssimulating how the gravitational field and mantle dynamics evolved. The results suggest that the AGL would have initially been weaker: it intensified later, especially between 30 and 50 million years ago.
This period coincides with large-scale climate changes in Antarctica, including the establishment of glaciations. The formation and expansion of ice, in turn, has cascading effects on ecosystems and the ocean system, impacting average sea level and even ocean chemistry, such as acidity.
The team argues that anomalies like the AGL deserve further investigation and now aim to test more direct links between the strengthening of the “gravity hole” and the evolution of ice sheets. For Forte, the central question is understanding “how the climate connects to what happens inside the planet” — and to what extent internal dynamics can help explain ice stability and sea level variations.
