Friday, 15 March 2013

Cook, Shackleton and now Melanie Leng: Preparing for an expedition to South Georgia


Image comprising a series of pictures stitched to show Myviken Bay looking along the Bore Valley from the North, South Georgia.
British Antarctic Survey © NERC
In a few days I'll be following in the footsteps of James Cook (1775) and Ernest Shackleton (1916) and embarking on an adventure in the South Atlantic. I'm bound for fieldwork on South Georgia, a remote and inhospitable island with no permanent inhabitants, approximately 200km SE of the Falkland Islands.   

Me!
 The Geology (& wildlife!) Bit

The Island has a complex geological history; it is part of a small block of continental crust bound to the north and south by inactive faults against the Antarctic and South American continental plates. The rocks that comprise the island are of Jurassic to Cretaceous age, largely formed of volcanic and sedimentary rocks which were subsequently metamorphosed. The hard metamorphic rocks form towering mountains on the island rising to in excess of 2000m. Fringing the island is a low lying zone which has been eroded by the retreating glaciers around 10,000 years ago. This relatively low lying coastal zone is home to tundra type vegetation, mostly grasses, mosses, lichens, ferns and an abundance of wild life. South Georgia is one of the most densely populated wildlife regions on the planet with vast colonies of penguins and seals as well as the non native reindeer, rats and mice which were introduced by man.


The Expedition Bit 

Once there I will be taking cores (tubes) of sediments from peat bogs, lakes, lagoons and in the shallow marine environment. The sediment that has accumulated in these environments has done so in a time ordered sequence, the oldest being at the bottom and the most recent at the top. By pushing tubes into the soft sediments we retain that time sequence of sediments. 

I plan to look at fragments of plants, tiny insects and the chemistry in the sediments to reconstruct the past environmental conditions since the glaciers retreated from the coastal zone. I expect to see warmer conditions (and retreating glaciers) around 9,000 years ago when the ice shelves collapsed in Western Antarctica, and cooler temperatures (and re advancement of glaciers) around 7-3,000 years ago when the ice shelves reformed in Western Antarctica. 

On South Georgia I will be taking cores of sediments
from different environments including lakes (using a
raft like colleagues on Lake Windermere)

By also looking at rates of warming and match those to recent ice shelf collapse I hope to be able to forecast what will happen around South Georgia in the future. By reconstructing climate and environmental change at different places around Antarctica I hope to unpick natural from anthropogenic global warming, and show how different areas are affected in different ways by the same global change. Our planet is an amazingly fragile place and understanding future impacts of higher atmospheric CO2 is paramount.

This expedition and research is in collaboration with the German Research Foundation, and I will be part of an international team of scientists travelling to South Georgia on board the German research ship, the Polarstern. We embark from Punta Arenas in southern Chile, will be dropped off on the NE coast of South Georgia, from where we hike inland with all our gear to make a base camp, we will be collected a few weeks later and taken to the Falkland Islands where the RAF are flying me home. Even today it is amazing how travel to and from South Georgia is difficult; imagine what Cook, the 19th century Norwegian sealers, and Shackleton had to endure! 
 
Chinstrap Penguins (Pygoscelis antarctica) on brash ice
in front of the Neumayer Glacier, Cumberland West Bay,
South Georgia. British Antarctic Survey © NERC
The weather of South Georgia during March and April will be autumnal, with average day time temperatures of around freezing, with squally showers from the westerlies that constantly thrash the island. Communication while I am away will be patchy, but I hope to update you when I can. Wish me luck!
 
Melanie Leng
Follow me on twitter @MelJLeng

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