Scientists trace South Georgia’s ice cap history20/03/17Environment
A team of scientists from the UK, Germany and Australia have discovered that South Georgia was seemingly covered by a giant ice cap.
Some 20,000 years ago the island’s glaciers pushed out 50km and more from their current positions, reaching to the edge of the continental shelf.
South Georgia was in effect covered by a giant ice cap.
This discovery is reported in the current edition of the journal Nature Communications and is the result of investigations of the seafloor.
Dr Alastair Graham from Exeter University, UK, said: “We were able to find a tracer of this ice cap – a ridge at the outer margin of the continental shelf that’s larger than all others, pretty much; and it’s fairly contiguous.
“You see it to the west, to the north, to the east, and even to the south where we don’t have much data. It’s quite a surprise because many scientists had assumed any ice cap was quite small.”
Graham and his colleagues conducted sonar surveys around South Georgia using the British Antarctic Survey’s (BAS) research vessel, the James Clark Ross, and Germany’s RV, the Polarstern.
These ships mapped the troughs cut by ancient glaciers.
The investigation revealed that the giant ice cap was at its fullest extent at the height of the last ice age – around 19 to 26 thousand years ago.
Then, as the global climate warmed, the glaciers went into a fast retreat, pulling back to positions not far beyond the present coastline.
Graham said: “In the last 10,000 years the ice cap has wobbled back and forth, but never really gone out much beyond the fjords.”
“And then in the 1950s, things seemed to go pear-shaped for South Georgia. The glaciers now are in a massive retreat, which could have quite serious implications for local ecosystems.”