Source: Te Herenga Waka—Victoria University of Wellington
It holds enough ice to raise global sea levels by three to four metres and, until recently, has been viewed as relatively stable. But a major new study is now calling for urgent research on East Antarctica’s Wilkes Subglacial Basin and its potential to dramatically increase sea-levels as the climate warms.
“The Wilkes Subglacial Basin is incredibly important for predicting future sea-level rise, but it’s also largely unexplored. The limited evidence we do have highlights the risk of rapid change as temperatures rise,” said study co-author Professor Nancy Bertler, a climate scientist at Te Herenga Waka—Victoria University of Wellington and Earth Sciences New Zealand.
Piecing together existing data on the region and using computer modelling to predict future changes, the study found retreat of this vast ice-filled basin could result in a sharp increase in meltwater, adding to sea-level rise and potentially disrupting ocean circulation and marine ecosystems.
Signs of change have already been seen. Since the 1990s, the basin’s main glacier—the Cook Glacier—has been thinning at an increasing rate. It currently discharges about 40 billion tonnes of ice each year.
“There is now broad scientific agreement that the basin has the potential to change under future warming, but we still don’t know how quickly change could occur, what climate thresholds may trigger large-scale retreat, and how much the basin may ultimately contribute to future sea-level rise,” said Professor Bertler.
These gaps in knowledge need to be urgently addressed, said lead author Professor Matt King from the University of Tasmania.
“The Wilkes Subglacial Basin is arguably the last unexplored place in Antarctica. No ship has ever been within 150 kilometres of the front of Cook Glacier. If we can understand this region and project its future better, we’ll be more prepared for future sea-level rise both here in the Pacific and globally,” said Professor King.
Risk of runaway retreat
The landscape hidden beneath the Wilkes Subglacial Basin is of major interest to scientists.
“The basin itself sits on bedrock that gets deeper inland, a feature that can lead to accelerating retreat as warmer seawater comes into contact with the ice and starts melting it from below. When this melting reaches a tipping point, the ice sheet can quickly become unstable,” said Professor Nick Golledge, an ice sheet modelling expert from Victoria University.
This phenomenon has been the focus of attention in parts of West Antarctica, where scientific efforts have largely been concentrated. It’s only recently been recognised that regions of East Antarctica have similar characteristics.
Clues to how the basin may change as the climate warms lie buried in marine sediment records from previous warm periods in Earth's history.
“Together, these sediment records and modelling studies indicate parts of this basin previously underwent substantial retreat when the Earth was warmer. The evidence points to a clear need to find out more about how this region will change as the climate warms,” said Professor Rob McKay, director of Victoria University’s Antarctic Research Centre.
International response needed
The study, co-authored by researchers from 14 countries, calls for a coordinated international effort to collect data on the Wilkes Subglacial Basin as quickly as possible.
Research priorities include mapping the seafloor and collecting sediment samples from deep beneath the basin to shine more light on changes that occurred in the past when the climate was similar to today’s.
“Existing seafloor maps are unreliable, we have sparse data on ocean temperatures, and sediment records are limited. We need to find out what’s happening beneath the sea ice—is warm ocean water already reaching the basin’s glaciers—as well as what’s happening on land,” said Professor Bertler.
Collecting this information will be no easy task. Thick sea-ice blocks regular ship and plane access for much of the year, hampering access to this remote region.
In response to changes occurring in the Antarctic sea-ice system, the Scientific Committee on Antarctic Research has established an action group to facilitate international collaboration, align research efforts, and coordinate field deployments. This initiative is led by Professor King, Professor Bertler, and Dr Laura De Santis from Italy's National Institute of Oceanography and Applied Geophysics.
“We’re asking governments, the scientific community, as well as philanthropists to support this research and help us find the answers to the crucial questions about the Wilkes Subglacial Basin and the climate risks it may be hiding,” said Professor Bertler.
The study is published in the journal Nature Reviews Earth & Environment.