Scientists have long known that there are “gravity holes” – areas where gravity is particularly weak – beneath the surface of Antarctica. Given the various threats currently facing the region, scientists want to better understand this anomaly. At last, they may have a new clue.

Perhaps unsurprisingly, changes in Antarctica’s gravity coincide with major changes in the region’s climate and geology. Historical analysis of Antarctic gravity holes detailed in recent paper scientific report The paper explains that the hole was initially weak, but became stronger between 50 million and 30 million years ago, when widespread glaciers covered Antarctica.

But the research team has yet to confirm whether and how the gravity hole could affect Antarctica, especially as the effects of climate change worsen each year.

Not all spots are equal

of geoid It is an uneven and irregular sea surface shaped by the influence of Earth’s gravity. Gravity varies from region to region on Earth, but the differences are so small that you won’t see people flying or being crushed by gravitational anomalies. For you and me, it’s very subtle. In the case of water, these gravity differences can have meaningful effects.

In fact, these changes have significant effects on the Earth’s oceans. For example, sea levels in areas of relatively low gravity, such as Antarctica, are usually lower than expected because water tends to flow toward areas of stronger gravity.

The term “cyclone” here refers to “a widespread depression in Earth’s gravitational field caused by a lack of deep mass,” the researchers explained in their paper. release Graduated from the Paris Institute of Geophysics.

trace the path of gravity

According to the paper, the research team used global earthquake records and “seismic, geodynamic, and mineral physics data” to reconstruct the 3D structure of the Earth’s interior. The team’s model took into account factors such as mantle dynamics, gravitational field data, and changes in the Earth’s rotational behavior.

“Imagine doing a CT scan of the entire Earth, but not an X-ray like you would in a doctor’s office. Earthquakes happen,” the study’s lead author Alessandro Forte, a geophysicist at the University of Florida, said in the paper. university statement. “Seismic waves provide ‘light’ that illuminates the Earth’s interior.”

The researchers then used similar techniques to “rewind the internal rock flow and trace changes back 70 million years.” Simulations revealed that gravity near the south pole was initially lowered by colder, denser material sinking deeper into the mantle.

Then, between about 50 and 30 million years ago, a hotter, lighter mantle began to rise from the depths, redistributing mass across the continents. The combination of a cold, sinking mantle and a hot, rising mantle amplified the overall lack of mass beneath the South Pole, the study explained.

something that sinks

Sea levels and tidal dynamics then influence climate patterns, so researchers believe a deeper understanding of the gravity hole could lead to new insights into Antarctica’s geological history, especially given the threats looming over the region today.

“A better understanding of how Earth’s interior shapes gravity and sea level will provide insight into the factors important to the growth and stability of large ice sheets,” Forte said.