The formation of Antarctica's vast East Antarctic Ice Sheet may have been driven not only by falling atmospheric carbon dioxide but also by the slow uplift of the continent itself, according to a new study. The findings highlight how interactions among tectonics, topography, climate, and ice-sheet dynamics can fundamentally shape Earth's long-term climate evolution. The East Antarctic Ice Sheet (EAIS) is the largest and oldest ice sheet on Earth. Its formation roughly 34 million years ago is widely attributed to a decline in atmospheric carbon dioxide (CO2), which triggered global cooling and glaciation. However, if the decline of CO2 alone drove this glaciation, a broad, synchronous cooling affecting both hemispheres should be evident. Instead, the Northern Hemisphere did not glaciate until more than 20 million years later, and evidence suggests that some parts of the Southern Ocean remained relatively warm for millions of years after the EAIS began to grow. This paradox has posed a long-standing question: just how did the EAIS form? Here, Thomas Gernon and colleagues argue that uplift of the Antarctic continent may have played a critical role alongside falling CO2 levels. To test this theory, Gernon et al. used a variety of geodynamic models, topographic reconstructions, ice-sheet models, and energy balance models to understand the long-term interaction between tectonic uplift, climate, and ice growth during the Eocene in the Dronning Maud Land and Gamburstev Mountain regions of Antarctica. The authors found that the formation of the EAIS was the culmination of a chain of geological and climatic events that began more than 120 million years earlier with the breakup of the Gondwana supercontinent. This tectonic reorganization gradually uplifted Antarctica's interior regions, creating high-altitude plateaus and mountain ranges that became cold enough to sustain extensive snow and ice accumulation by 45-40 million years ago. This regional uplift enabled rapid ice-sheet expansion, despite the surrounding Southern Ocean being relatively warm.
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