Antarctic: Scientists unexpectedly discover concealed river system the size of Germany and France combined
The surprising discovery of a 460-kilometer-long river beneath the Antarctic ice sheet may accelerate ice melting as the planet warms, according to a new study published in Nature Geoscience today (Oct .27).
While the discovery gives us a new perspective on how a changing Antarctic can affect the planet, it also reminds us how much more there is to learn about the continent.
'There are whole systems down there, interconnected by vast river networks'
Researchers from Imperial College London, the University of Waterloo in Canada, Universiti Malaysia Terengganu, and Newcastle University made the discovery.
The study describes how the river gathers water from an area the size of Germany and France combined at the base of the Antarctic ice sheet. They demonstrate that the ice sheet's foundation has more active water flow than was previously believed and argue that this may make it more vulnerable to climatic changes.
"When we first discovered lakes beneath the Antarctic ice a couple of decades ago, we thought they were isolated from each other. Now we are starting to understand there are whole systems down there, interconnected by vast river networks, just as they might be if there weren't thousands of meters of ice on top of them," said Professor Martin Siegert in a press release, who is from the Grantham Institute at Imperial College London and is co-author of the study.
"The region where this study is based holds enough ice to raise the sea level globally by 4.3 meters. How much of this ice melts, and how quickly, is linked to how slippery the base of the ice is. The newly discovered river system could strongly influence this process," Seigert added.
Ice sheet hydrology models and airborne radar measurements revealed a river system beneath the ice
The discovery was made by combining ice sheet hydrology models and airborne radar measurements that allow researchers to see beneath the ice. The team concentrated on an understudied and largely inaccessible region that contains ice from both the East and West Antarctic Ice Sheets and extends to the Weddell Sea.
"From satellite measurements, we know which regions of the Antarctic are losing ice and how much, but we don't necessarily know why. This discovery could be a missing link in our models. We could be hugely underestimating how quickly the system will melt by not accounting for the influence of these river systems," explained lead researcher Dr. Christine Dow from the University of Waterloo.
The new study debunks a previous theory that assumes the Antarctic has 'tiny amount of water'
There are two major ways that water can get beneath ice sheets. One way is through melting at the base brought on by friction as the ice moves over land and the inherent heat of the Earth. Another way is through surface meltwater flowing downward through deep crevasses (moulins).
In the Antarctic, the summers are too cold to produce sufficient amounts of surface melting to create moulins. It was therefore assumed that this indicated there was just a tiny amount of water present at the foot of the Antarctic ice sheets.
The latest finding refutes this theory by demonstrating that there is enough water from basal melt alone to form significant river systems beneath kilometers of thick ice.
Could the Antarctic be heading to a Greenland-like state of rapid ice loss?
For instance, future summer temperatures could rise to the point where the ice sheet's base is reached by surface melt. This might significantly impact river systems and push the Antarctic to a Greenland-like state, where ice loss is more rapid.
Additionally, there may be feedback loops that increase the melting of the ice. For instance, if the ice begins to flow more quickly as water builds up at the base, this will increase friction as the ice travels over dry terrain and may lead to an increase in basal melting and water production.
Future research is underway to learn more about the Antarctic's impact on Earth
The team is now collecting more information from surveys regarding these novel systems. They hope to adapt their models to other areas to understand better how a changing Antarctic could influence the planet.