The British Antarctic Survey (BAS) has released the most detailed map of Antarctica yet, showing what it would look like after stripping away the ubiquitous ice and snow cover. The map, based on 60 years of data, will help scientists better understand ice flows.
Antarctica is the most difficult of all continents to map because nearly its entire land surface and even much of the surrounding seabed are sealed beneath an eternal ice sheet that contains 70% of the world's freshwater supply. The average thickness of the ice sheet is 1.2 miles (1.9 kilometers), and mapping it requires more than a theodolite, a ranging pole, and a pot of coffee.
In fact, BAS says it had to use six decades of radar, sonar and gravity anomaly readings collected by planes, satellites, ships and dog sleds (although dogs are terrible at determining bearings), combined with complex computer models, to complete what it calls Bedmap3.
It is the third such map produced by the National Academy of Sciences and an international team of scientists since 2001. The aim is to peel back the 6.5 million cubic miles (27 million square kilometers) of ice sheet to reveal the bedrock underneath.
The result is a new map of the Antarctic continent that is far more detailed than any previous map. The discoveries include Antarctica's highest mountains and deepest canyons, as well as the ice's deepest point reaching 15,607 feet (4,757 meters).
According to BAS, the purpose of this is not just for the completeness of the map. It also sheds light on the mechanics of Antarctica - in particular how glaciers flow on its surface and how underground rivers of warm water affect the ice, which could have global consequences.
Dr Hamish Pritchard, a glaciologist at the National Institute for Scientific and Industrial Research and lead author of the study, said: "This is the basis of the computer models we use to study how ice and snow will flow across the continent as temperatures rise. Imagine pouring syrup on a stone cake - all the lumps, all the bumps and bumps will determine where the syrup flows and how fast it flows. The same is true in Antarctica: some ridges block the flow of ice; and depressions and smooth places are where the ice can accelerate."
One odd thing about this bedrock map is that its accuracy depends on the presence of ice. If you remove the ice, everything changes. First, the water on the ice must flow elsewhere, which would cause global sea levels to rise 190 feet (58 meters).
Even stranger is the fact that the ice sheet weighs an astonishing 24.759 megatons. If it were removed, the entire continent would spring back, pushing it out into the ocean, just as Europe, North America and Asia have been rising in the roughly 12,000 years since the end of the last ice age.
This is why terms like mean sea level are not as simple as they first appear, and often cause great distress to oceanographers and geodesists.
The research was published in Scientific Data.