An international team called for an urgent need to study the least understood region of Antarctica, which contains enough ice to raise the global average sea levels by an estimated three to four metres. This is the Wilkes Subglacial Basin, one of the areas of East Antarctica most vulnerable to the effects of climate change, yet the least explored to date. To gauge the climate risk hidden beneath the ice in East Antarctica, the scientific community would need to be able to answer the most basic questions: is warm ocean water reaching the glaciers? What does the continental shelf look like beneath the ice? Are we approaching the threshold of warming that could trigger large-scale ice retreat?
These are the issues addressed in an article in the journal Nature Reviews Earth & Environment , authored by experts from 14 countries and to which Dimitris Evangelinos, a researcher from the Marine Geosciences Research Group (Gmar) at the Faculty of Earth Sciences of the University of Barcelona, has contributed.
The study is led by Matt King, from the Australian Centre of Excellence in Antarctic Sciences (ACEAS) and the University of Tasmania, reviews findings from geology, oceanography, climatology, satellite observations and ice sheet modelling to assess the current state of knowledge regarding this vast ice-filled basin.
Perhaps the last unexplored place in Antarctica
"The Wilkes Subglacial Basin is arguably the last unexplored place in Antarctica," says Professor King, the paper's lead author. "No ship has ever been within 150 kilometres of the front of one of the key glaciers, the Cook Glacier. There is no in situ seabed mapping data of the sea floor, and we have very limited information about the oceanic conditions that could drive future melting."
The Wilkes Subglacial Basin measures approximately 1,400 kilometres by 400 kilometres and consists of an ice sheet sitting on a bedrock much of which is deeper than 2,000 metres below sea level. "Much of the continental shelf off the basin is covered by sea ice for much of the year, and in some areas it is exceptionally thick," notes Evangelinos, a member of the Department of Earth and Ocean Dynamics at the UB.
According to various projection models, "if the retreat exceeds certain stabilization points on the bedrock, it could accelerate and reach speeds of up to approximately one kilometre per year", warns the researcher. "The models also indicate that, during this century, conditions could arise that trigger changes in the ice sheet which would continue to unfold over thousands of years."
The characteristics of the basin could make the ice sheet particularly vulnerable to ocean-driven melting and retreat. "The bedrock of this basin has a retrograde slope: in other words, rather than becoming progressively shallower towards the interior of the continent, it becomes deeper. This geometry may contribute to the instability of the marine ice sheet," says Evangelinos.
"The ocean also plays a key role," he continues. "If relatively warm ocean water reaches the cavities beneath the ice shelves, it can increase basal melting, thin the ice shelves and reduce the restraining effect they exert on the inland glaciers."
