The Coldest Continent
Antarctica is the coldest continent on Earth. At the South Pole, the average temperature is -49°C and the lowest temperature ever recorded on Earth (-89.2°C) was recorded at the Russian Base Vostok in Antarctica in 1983.
Antarctica in winter and summer temperature ranges
One of the reasons why Antarctica is so cold is that the continent’s permanent ice cover reflects about 80% of the Sun’s radiation – this means that only 20% of the energy from the Sun is absorbed. This explains why Antarctica remains cold, even in the long daylight periods of summer. Scientists call this the albedo effect and very simply it means that dark colours soak up heat while white reflects heat away. You can try this effect for yourself by seeing what the difference is between wearing a white T-shirt on a hot, sunny day and then wearing a black T-shirt.
Another reason why Antarctica is so cold is its location over the Earth’s South Pole. How much heat an area receives from the Sun depends on whether the Sun is overhead or not. This is why it is always hot near the equator, as the Sun is almost directly overhead. Because the Earth’s surface curves, at the poles, the Sun’s rays are spread over a wide area and so temperatures are almost always below 0°C.
Winters are severe in Antarctica, not only because of the low temperatures, but also because of the long periods of darkness. At New Zealand’s Scott Base, the sun sets at the end of April and is only seen rising again at the end of August. For two of these four months, there is complete darkness.
Antarctica’s low temperatures greatly affect the sea ice that surrounds the continent. Not only does the sea ice vary in amount between summer and winter, its presence is dependent on Antarctica’s low temperatures and in turn, the weather in Antarctica relies on the sea ice because there is so much of it in contact with the air.
BAS Scientist with weather balloon
BAS Scientists regularly take meteorological measurements in Antarctica for weather forecasting locally, and on a global scale as even small changes to Antarctica’s climate could have important implications for the whole world. However BAS knowledge on the workings of Antarctica’s climate system is far from complete and so research is ongoing to develop further understanding of the interactions between Antarctica’s atmosphere, sea-ice and ocean.
The main ocean current in the southern hemisphere is the Antarctic Cicumpolar Current (ACO), which flows around Antarctica. The ACO acts as a “conveyor belt”, mixing the waters of the Atlantic, Pacific and Indian Oceans and helping to control their climates.
But global warming could cause a slowdown in this system if the cold salty water of the Antarctic became too warm or diluted with too much fresh water from melting glacier ice. Scientists believe that such a slowdown would create a major influence on many places on Earth, as they would become much hotter or colder then they are now.
That might not sound too bad, but as temperatures change, so rainfall patterns shift and conditions change in climate zones. Living things are perfectly suited to the climate in which they live and they may die out if they can’t adapt rapidly enough to the new conditions. Eventually we could lose plants from all over the world that are currently used to treat serious illnesses and as all animals eat or are eaten by other living things, some animals could starve and be lost forever.
Flood in South Asia
Global warming would also have a direct effect on people. Some effects of global warming, such as flooding, threaten food supplies and clean water. Also, more areas of the world would be warm enough for harmful insects and germs to thrive, which will lead to widespread outbreaks of insect-carried diseases like malaria.
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