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07-08-2024

Antarctic ice sheet: Past, present, and future

Recent research highlights the accelerating melt of the Antarctic ice sheet, particularly in West Antarctica, driven by global warming. 

Glaciation of Antarctica 

An international team led by the Alfred Wegener Institute has discovered that the permanent glaciation of Antarctica began around 34 million years ago, initially confined to East Antarctica. 

Sediment samples and climate modeling indicate that West Antarctica remained ice-free until at least seven million years later. 

These findings suggest that East and West Antarctica responded differently to external climatic changes, with East Antarctica glaciating first due to conducive climatic conditions and topography, while West Antarctica only later experienced ice sheet advances.

Transition to an icehouse world 

The transition from a greenhouse world to an icehouse world around 34 million years ago marks one of Earth’s most significant climate shifts, leading to the formation of the Antarctic ice sheet. 

However, data gaps, especially from West Antarctica, have left uncertainties about the exact timeline and mechanisms of this glaciation. 

The experts filled these gaps by analyzing a drill core retrieved offshore from the Pine Island and Thwaites glaciers. The findings show that East Antarctica saw the first large-scale glaciation while West Antarctica remained ice-free, characterized by dense forests and a temperate climate.

West Antarctica’s ice sheet lagged behind

Combining new sediment data with climate models, the researchers demonstrated that the conditions necessary for permanent ice formation were present only in East Antarctica’s coastal regions, particularly Northern Victoria Land. 

Here, moist air masses and the rise of the Transantarctic Mountains facilitated snow accumulation and ice cap formation, which then spread inland. 

In contrast, West Antarctica’s ice sheet formation lagged by millions of years, requiring significantly colder conditions to develop due to its below-sea-level topography in many areas.

Differing responses to climate change 

These findings underscore the differing responses of East and West Antarctica to climatic changes. Even slight warming can trigger significant ice melt in West Antarctica, a concern given current global temperature trends. 

The research provides crucial insights into the historical climate transition from greenhouse to icehouse conditions and improves climate models that predict the interactions between ice, ocean, and atmosphere.

Closing critical knowledge gaps 

The researchers utilized advanced technology, including the MARUM-MeBo70 drill rig, during the 2017 expedition PS104 on the research vessel Polarstern, to extract sediment cores from previously inaccessible hard seabed off West Antarctica. 

These technological advancements enabled them to uncover new data, closing critical knowledge gaps about Antarctica’s glaciation history and enhancing our understanding of future climate dynamics.

Significance of the study

Dr. Johann Klages of the Alfred Wegener Institute, who led the research team, emphasized the significance of these findings for contemporary climate studies. 

“Even a slight warming is enough to cause the ice in West Antarctica to melt again – and that’s exactly where we are right now,” Klages said. This knowledge is vital as the world faces potential fundamental climate changes akin to those experienced millions of years ago.

The integration of geological data with sophisticated climate models offers a more detailed and accurate picture of how Antarctica’s ice sheets have evolved and how they might respond to future climate scenarios

The study, published in the journal Science, not only illuminates past climate dynamics but also informs strategies to mitigate and adapt to ongoing and future climate impacts.

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