A recent exploration has discovered the existence of ancient river valleys beneath the East Antarctic ice sheet. This finding suggests that this region of Antarctica may have been covered in ice for over 30 million years, providing valuable insights into how the ice will respond to future climate change. While most of Antarctica is covered in a thick sheet of ice, radar measurements have offered limited details about the hidden topography.
Researchers, led by Stewart Jamieson at Durham University, used satellite radar measurements of the East Antarctic ice sheet’s surface to gain a new perspective. By comparing the inferred topography from the ice surface with direct measurements taken by ice-penetrating radar during aerial surveys, the team identified a distinct region known as “Highland A”. This 32,000-square-kilometre area is characterized by three land blocks separated by wide troughs, similar to fjords. Without the ice, the topography of Highland A would resemble the peaks and valleys of the Lake District in the UK.
According to the researchers, these features provide insights into the geological history of the region, dating back to the separation of Antarctica from the Gondwana supercontinent around 180 million years ago. They propose that rivers flowing through rifts formed by the break-up shaped the fjord-like troughs which were then further sculpted by glaciers during a cooling period approximately 34 million years ago. As the ice sheet grew and cooling intensified, the surrounding areas’ topography was eroded, but Highland A’s features were preserved due to the glaciers forming a protective mechanism against erosion.
These discoveries shed light on the stability of the East Antarctic ice sheet, which has received less attention compared to the West Antarctic ice sheet in previous research on melting ice. Understanding the stability of this region over millions of years is crucial for developing accurate models that predict the response of the ice sheet to climate change. The preservation of Highland A suggests a high level of stability, at least in that specific area. However, some scientists, like Sean Gulik from the University of Texas at Austin, believe that the ice sheet may have experienced fluctuations as recently as 1.5 million years ago, indicating potential sensitivity to current warming. The limited knowledge about what lies beneath the ice sheet makes it challenging to comprehend its behavior fully.
