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Antarctic Science Facts

Working with an ice core

How can you tell how old the ice is in the ice cores you drill?

The chemical composition of snow changes with the seasons, and this allows a dating of the ice near the surface by counting the annual cycles as you drill downwards. For example, in Antarctic ice, sea salt (at around 1 part per million in snowfall) increases as the winds increase and as the sea ice cover of the Southern Ocean pulses in and out during the year. We also discover that more snow falls in warmer years. You can check the age of ice at particular depths by observing the debris from nuclear bomb tests and from major volcanic eruptions. These provide a "time-line" across the whole of the Earth. The deeper you drill the more the layers become squashed, because the ice is flowing in a glacier. Eventually the whole cycle is smeared out and the annual layer becomes too thin to detect the seasons. Then glaciologists use mathematics and physics to calculate the age of the ice. They use knowledge of how ice deforms, together with the connection they found between temperature and rates of snowfall near the surface. Finally these calculations can be checked in a cunning way. During the many changes of climate that have affected the Earth the gas methane has changed its concentration in the atmosphere dramatically. Methane together with other gases are trapped in the ice, and changes in the concentration of methane are used in the same way as volcanic eruptions to identify an event that occurred simultaneously around the world. Dating is also checked by looking at tree rings (outside Antarctica!) and changes in deep-sea sediments that are both also climate controlled. There is less uncertainty in providing their dates because sediments and wood don't flow like glaciers!

Is there a possibility that volcanic and seismic activity from volcanoes such as Mt Erebus could cause part of the Antarctic continent to break off?

There is a slight risk that volcanic and seismic activity could cause a loss of ice from the Antarctic. Heat generated by volcanic activity could melt ice, especially if the volcano was actually under the ice sheet, having been buried by 30 million years of snowfall.

Parts of the Antarctic ice sheet are breaking off all the time. Iceberg production is the final part of the flow of glaciers downhill to the sea. It is only when there is more ice breaking away than in earlier years can we be sure that the ice cover is shrinking. Currently this is the case in the warmest part of the Antarctic - the Antarctic Peninsula. The ice is retreating and the scientists are now very sure that climate warming is to blame.

I don't know about the whole of Antarctica but I can tell you about the plant and animal life in our local area. Wherever you go around Rothera and its local islands you will see lots of lichens. There are approximately 100 species on the Antarctica Peninsula, and they come in many exciting shapes, sizes and colours. My favourites are the large cup-shape Umbilicaria lichens on Lagoon Island, which have grown as big as dinner plates. Lichens are very good at invading new and hostile environments, which can then help the mosses and other plants to grow. There are approximately 40 species of mosses on the Antarctic Peninsula. We have only two types of flowering plants on the Peninsula, the most common is a grass, Deschampsia Antarctica, and the other Colobanthus quietensis. They both like to grow in very sheltered spots with the mosses and lichens, where soil and water has been trapped.

For those of you that like insects we have two major types of creepy crawlies that live in the patches of moss and lichens, and under stones. There are the mites (Acari), and the springtails (Collembola), and we have a few species of each in our area. These tiny insects manage to survive the extreme cold temperatures of the Antarctic winter by producing a chemical similar to antifreeze.

At Rothera this year we have seen many Ad?e penguins, a few chinstrap penguins and one emperor penguin who seemed to be lost. He stayed around the base for a month and we called him Billy. The Ad?es are incredibly funny to watch and I have seen them run up and down our runway in long lines before jumping into the sea. They look very clumsy on land, hopping, waddling, falling on their bellies, and tripping over rocks.

I have seen some magnificent birds during my time here including the pure white snow petrels, the big ugly giant petrels, patterned cape petrels, the tiny Wilsons petrels, fulmars, gulls, blue-eyed shags, skuas and terns. Five types of seals have visited Rothera Point, the Weddell, crabeater, leopard, elephant and fur seals. Elephant seals are my favourite as they are big, fat, smelly and burp a lot. Within the next month the Weddell seals will start to come ashore and have their pups so look out for cute pictures on the BAS web site. I have also been very lucky to see minke whales and humpback whales in the bay to the south of Rothera and hopefully I will soon see a killer whale. Several were spotted during the summer but I was never on base at the time.