🌍 Is climate linked to the gravitational anomaly under Antarctica?
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It is not a hole in the ground. The force of gravity naturally changes on the Earth's surface depending on the distribution of masses at depth. In this region, the gravitational force is reduced by a tiny, imperceptible amount for a human. An object weighing 100 kilograms (about 220 lbs) would weigh only a few grams less here, but this difference reveals major geological processes.
Maps showing the evolution of Earth's geoid anomalies at three time periods: 65 million years ago, 40 million years ago, and today.
These maps are calculated from a reconstruction of the Earth's mantle structure. A fourth map shows current anomalies obtained with a modern tomographic model. The yellow star indicates the current location of the Earth's geoid lowest point. The magenta star marks the area of maximum geoid depression after correcting for the gravitational effect of the crust.
Comparisons with observations show a strong correspondence, reaching up to a 96% reduction in the discrepancy over Antarctica.
To understand this anomaly, researchers used images of the Earth's mantle obtained from seismic waves. By modeling the flow of rocks over millions of years, they were able to reconstruct the evolution of this gravitational low. Their simulations reveal surprising persistence. The work, led by the University of Florida, indicates the phenomenon is consistent and long-lasting, offering a glimpse into internal dynamics.
This anomaly is therefore not a passing phenomenon. It has existed for about 70 million years, even though its intensity has evolved over time. Models show that changes coincide with major geological events, such as the glaciation of Antarctica 34 million years ago. This synchronization suggests that internal processes could influence surface conditions, although direct links remain to be confirmed.
The change in gravity could influence the local sea level. This raises new questions about the interaction between Earth's internal processes and the climate. Scientists are now exploring how these gravitational changes could affect the stability of ice sheets, with implications for understanding our planet's past and future.
Furthermore, these discoveries are not only about Earth. On other planets like Mars or Venus, analogous gravitational anomalies could reveal long-term internal dynamics. Earth, with its seismic and geological data, offers a case study for reconstructing the evolutionary history of planets, enabling comparisons across the Solar System.
The results of this research have been published in the journal Scientific Reports. The next steps include coupled modeling to test climate hypotheses, with the hope of further clarifying these interactions.