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Amazing Antarctica
Factfile |
 Amazing Antarctica |
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The Iciest Continent |
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At 14 000 000 sq km (5 400 000sq miles), Antarctica the fifth largest continent, after Asia, Africa, North America, and South America. At over 58 times the size of the United Kingdom, in winter, this area is extended by pack ice, which forms when the sea water around the continent freezes.
Ice sheet - BAS
Antarctica is the world’s iciest continent with only some parts of the Antarctic Peninsula managing to escape as ice free as an enormous ice sheet, in places up to 4700 m thick permanently covers the region. As this great ice sheet gradually creeps outwards and spills on to the surrounding sea, much of the continent is fringed with floating ice shelves, with the Ross and the Ronne-Filchner ice shelves each being larger than the British Isles. From these ice shelves massive icebergs break off and drift northwards. Each year, two thousand trillion tonnes (2,000,000,000,000,000) of ice leaves Antarctica in the form of icebergs.
Iceberg
Antarctica’s ice sheet contains 30 million km³ of ice, which holds around 90% of the fresh water on the Earth’s surface. But how does Antarctica’s ice sheet have a profound effect not just on the continent itself, but on a global scale?
Antarctica’s ice sheet has been formed over thousands and thousands of years by snowflakes, that fall on the ground and build up year-by-year. As the weight of more snow above squashes these snowflakes, slowly air gets squashed out of the snow and eventually it turns to glacial ice.
Antarctica’s ice sheet may look in a steady state but is it actually a constantly changing body as the ice sheet acts like a conveyor belt, taking snow from the atmosphere and delivering ice back to the sea, creating ice shelves. But the speed at which ice shelves break up to form icebergs can be a sign of climate change.
Larsen B satellite image
Climatologists use satellite image to look at ice shelves. The image above shows Antarctica’s Larsen B shelf in early 2002, when 3250 km ² of ice 200m thick broke off. The shelf had previously been stable for 10 000 years and such an event has been linked to the ongoing climate warming in the Antarctic Peninsula, about 0.5° C per decade since the late 1940’s, almost certainly as a result of global warming.
BAS scientists with ice cores
Currently British Antarctic Survey (BAS) scientists in Antarctica are currently comparing current levels of greenhouse gases with past levels, by analysing ancient air bubbles trapped in glaciers and ice sheets. The deepest ice in Antarctica contains air and dust that’s over 240,000 years old. By then feeding their data into computers, scientists are able to create climate models and these can help us to understand past climates and also give clues to future climate change which ultimately will help us to avoid damaging the Earth's climate further.
One of the many `big questions' for scientists about Antarctica, is what might happen if the global climate warmed up? Over the last century the amount of carbon dioxide, nitrous oxides and methane in the atmosphere has been increasing rapidly mainly as a result of burning fossil fuels. These are `greenhouse' gases in that they tend to prevent radiated heat from escaping from the Earth's atmosphere, in the same way that the glass of a greenhouse traps heat. Over time, it is likely that the accumulation of greenhouse gasses could lead to an increase in global temperatures and the melting of the polar icecaps, so many countries around the world would be flooded. Low-lying cities, such as New York and London, as well as whole countries like the Netherlands, could be flooded. At these temperatures, many of the animals in the polar regions would die out too.
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