What lies beneath: Scientists make shocking discovery under the Antarctic Ice Sheet

Daily Mail​

7 days ago

It is the least explored continent in the world, famous for its harsh and remote environment.
Now, scientists have made a shocking discovery lurking beneath the Antarctic Ice Sheet.
Researchers have discovered 332 hidden trenches known as submarine canyon networks carved deep into the ocean floor - five times more than previously thought.
Some of these underwater trenches reach staggering depths of up to 13,000 feet (4,000m) - roughly as deep as Mont Blanc is tall.
Scientists have found roughly 10,000 submarine canyons all over the world.
And with just 27 per cent of the sea floor mapped in detail, there are likely to be many more waiting to be found.
However, the researchers say those beneath Antarctica's ice are the largest and most impressive anywhere on the planet.
David Amblas, of the University of Barcelona, says: 'The most spectacular of these are in East Antarctica, which is characterized by complex, branching canyon systems.'
Scientists have made a shocking discovery lurking beneath Antarctica's Ice Sheet (pictured), and it could have big implications for global sea level increases
The submarine canyons around Antarctica are so large because they are carved by a phenomenon known as turbidity currents.
These are underwater avalanches of sediment and water, which flow at speeds up to 45 miles per hour down the steep slopes of the continental shelf, digging out deep channels as they pass.
Dr Amblas says: 'Like those in the Arctic, Antarctic submarine canyons resemble canyons in other parts of the world.
'But they tend to be larger and deeper because of the prolonged action of polar ice and the immense volumes of sediment transported by glaciers to the continental shelf.'
These vast canyons play a vital role in a number of important ocean processes.
They transport nutrient-rich sediment from the coast to wider ocean, connect shallow and deep waters, and create habitats rich in biodiversity.
However, despite being so important, these unique environments remain profoundly understudied - especially in remote, hard-to-reach locations like the Antarctic.
In their paper, published in the journal Marine Geology, Dr Amblas and his co-author used the most complete and detailed map of the Antarctic to hunt for previously unnoticed canyons.
By analysing the map with a semi-automated method for identifying canyons, the researchers found far more canyons beneath the ice than had previously been expected.
Interestingly, these new maps revealed that there is a big difference between the canyons in different parts of the continent.
Co-author Dr Riccardo Arosio, a marine geologist from University College Cork, told MailOnline: 'It has been very interesting to discover a striking difference between East and West Antarctic canyons, which had not been observed before.'
Dr Arosio says that those in the East form 'long canyon-channel systems, and have more frequent U-shaped profiles'.
Meanwhile, canyons in the West of the continent are 'shorter, steeper, and V-shaped'.
This is likely because the canyons in the West have been carved by the water released by relatively recent melting of the ice sheet while those in the East are the product of a much longer process of glacial activity.
The researchers say this discovery could have much wider implications for how we predict the impacts of climate change.
The Antarctic canyons help exchange water between the deep ocean and the continental shelf.
This allows cold, dense water formed near the ice sheet to sink into the deep ocean, and drive global ocean circulation currents that help keep the climate stable.
At the same time, these canyons also bring warmer waters in from the open sea up to meet the floating ice shelves - driving the ice melt, which is weakening Antarctica's inland glaciers.
By affecting how quickly water from the ice sheet enters the ocean, these channels have a direct impact on global sea level increases.
However, the ocean models used by organisations such as the Intergovernmental Panel on Climate Change (IPCC) don't take the effects of these hidden canyons into account.
Dr Arosio says: 'Omitting these local mechanisms limits the ability that models must predict changes in ocean and climate dynamics.'
In the future, by gathering more high-resolution data in unmapped areas, the researchers expect to find even more submarine canyons beneath the ice.
Properly understanding these canyons and how they affect the circulation of water around the poles could be key to accurately predicting the impacts of climate change.
Antarctica's ice sheets contain 70% of world's fresh water - and sea levels would rise by 180ft if it melts
Antarctica holds a huge amount of water.
The three ice sheets that cover the continent contain around 70 per cent of our planet's fresh water - and these are all to warming air and oceans.
If all the ice sheets were to melt due to global warming, Antarctica would raise global sea levels by at least 183ft (56m).
Given their size, even small losses in the ice sheets could have global consequences.
In addition to rising sea levels, meltwater would slow down the world's ocean circulation, while changing wind belts may affect the climate in the southern hemisphere.
In February 2018, Nasa revealed El Niño events cause the Antarctic ice shelf to melt by up to ten inches (25 centimetres) every year.
El Niño and La Niña are separate events that alter the water temperature of the Pacific ocean.
The ocean periodically oscillates between warmer than average during El Niños and cooler than average during La Niñas.
Using Nasa satellite imaging, researchers found that the oceanic phenomena cause Antarctic ice shelves to melt while also increasing snowfall.
In March 2018, it was revealed that more of a giant France-sized glacier in Antarctica is floating on the ocean than previously thought.