Deep Earth Dynamics Behind East Antarctica's Ice Sheet: Mantle Waves, Uplift and the Two Ice-Age Mysteries

Overview

An international team proposes that East Antarctica’s ice sheet was primed by deep Earth processes rather than climate alone. They trace how mantle waves, generated during the breakup of the Gondwana supercontinent, destabilised the base of the adjacent continent and gradually lifted its interior. This uplift, culminating in a vast plateau that could sustain year-round snow, helped East Antarctica glaciate around 45 million years ago—even as Arctic regions remained relatively ice-free for tens of millions of years more. The result reconciles a long-standing puzzle about why the Arctic cooled later and why Southern Ocean temperatures stayed unexpectedly warm after the ice sheet formed.

• Mantle waves from Gondwana breakup uplift East Antarctica’s Gamburtsev region, enabling glaciation.
• Elevation thresholds around 2 km allowed snow and ice to persist year round.
• Arctic cooling lagged behind due to topographic constraints, while the Southern Ocean remained warm after East Antarctica glaciate.
• Geology can precondition climate for ice ages, shaping future ice-sheet behavior.

Author: Science

Introduction

East Antarctica hosts the largest ice sheet on the planet, holding enough water to raise sea levels by about 52 meters if it were to melt completely. Two intertwined mysteries have long challenged scientists: first, why Antarctica became ice-covered roughly 34 million years ago during the Eocene-Oligocene transition while the Arctic stayed ice-free for another 25 million years; and second, why Southern Ocean surface temperatures remained unexpectedly warm for about 10 million years after the East Antarctic Ice Sheet formed. A new study, published in Science, suggests the answer lies deep beneath the ice: Antarctica’s own mountains and the slow, mantle-driven tectonic forces that built them. This work builds on a growing view that deep Earth processes can influence surface climate on long timescales, setting the stage for ice ages before climate crosses the necessary thresholds.

From Gondwana to Gamburtsev

The narrative begins about 170 million years ago when Antarctica and Africa were still connected in the Gondwana supercontinent. Their subsequent breakup sent Antarctica on a rapid journey toward the South Pole and triggered a chain of sub-surface events. Mantle upwellings beneath breaking continents create mantle plumes and waves that propagate through the rock below continents for tens of millions of years. In their Nature investigations, the researchers show that these mantle waves could trigger diamond-bearing volcanic eruptions far below the surface, lifting large portions of the continental crust as the deep roots are removed and reconfigured. The waves also generate uplifts away from the original rift zones, a phenomenon the team traces to East Antarctica.

Using computer models that simulate landscape evolution over tens to hundreds of millions of years, the team linked these mantle waves to a coastal escarpment that grew more than two kilometers high. Inland, the waves stripped away rock from deep beneath the continent, allowing the land to rise gradually. The Gamburtsev mountains, now buried under kilometers of ice, became the focal point of this uplift and the subsequent paths of erosion and topographic development.

Uplift and the Ice Sheet

Elevation plays a pivotal role in ice formation. The model calculations indicate a critical elevation threshold around two kilometers. Before this threshold was crossed around 50 million years ago, the Gamburtsev region sat too low for snow to survive the summer. Beginning around 45 million years ago, the mantle-waves’ uplift pushed much of the range above 2 km, enabling snow and ice to persist through summers and eventually coalesce into glaciers. This uplift coincided with a global cooling trend that reduced mean temperatures from roughly 30°C to around 20°C over a 50-million-year period, but the Arctic did not reach the same threshold required for widespread glaciation. The authors conclude that the East Antarctic ice sheet could begin to form under regional topographic conditions even as global temperatures remained comparatively moderate and Arctic ice remained limited for a longer period than expected.

Feedbacks and Reconciliation of the Mysteries

Two feedback mechanisms amplified ice-sheet growth. First, increasing ice and snow cover reflect more sunlight than exposed rock, contributing to regional and possibly global cooling. Second, cooling over Antarctica reduces atmospheric water vapor, a potent greenhouse gas, weakening the insulating blanket and allowing temperatures to fall further. Together, these loops enabled the ice sheet to extend from its highland refugia toward the coast, eventually merging into the present-day East Antarctic Ice Sheet. The model also explains why global cooling was not sufficient to freeze the Arctic: the Arctic landmasses lacked the elevation needed to cross the same threshold as Antarctica, so major Arctic ice sheets did not form for another 25 million years or more. Additionally, the global cooling from ice sheet formation did not by itself dramatically lower polar ocean temperatures, helping reconcile the mysteries regarding East Antarctica’s origin of the ice sheet and the Southern Ocean’s warmth after glaciation.

Setting the Stage for Ice Ages

The paper emphasizes a broader principle: the height of the land can determine whether a particular climate yields cold enough conditions for ice sheets. If deep Earth processes can condition a landscape for ice well before climate cools to the necessary levels, they may have contributed to earlier ice ages as well. The work also underscores a fundamental point about future climate: continental ice sheets form under highly specific conditions and on geological timescales, and their melting would occur far more rapidly than their formation. Once ice sheets are lost, they are unlikely to regrow quickly in the same manner without equally long and unlikely changes in climate and sea-temperature patterns.

Implications for Past and Future Climate

Beyond addressing the East Antarctica enigmas, the findings offer a framework for understanding other climate events in Earth’s history. If deep Earth dynamics can condition landscapes long before climate changes push ice formation, such processes may have played a role in other past ice ages as well. In terms of future climate, the study highlights the fragility and slow pace of continental ice sheets; while climate can shift more rapidly, rebuilding such ice would require long timescales and the convergence of multiple geological and climatic factors.

Conclusion

The study presents a compelling view that East Antarctica’s ice sheet did not simply arise from atmospheric cooling. Instead, slow, deep Earth processes—mantle waves triggered by the breakup of Gondwana—set the stage by lifting East Antarctica’s interior to elevations favorable for persistent snow and ice formation. The research integrates geological history with climate evolution, providing a coherent narrative for two long-standing mysteries, and offering a lens through which to examine the potential role of deep Earth processes in shaping Earth’s climatic past and future.