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In this chapter:

  • Temperatures on the Antarctic coast are warmer than temperatures further inland
  • Temperatures on the Antarctic Peninsula are rising
  • Melting ice is natural, but problems are caused when there is too much melting ice
  • Humans have increased the amount of greenhouse gases in the atmosphere
  • There is a hole in the ozone layer above Antarctica

Introduction

Scientists believe that the Earth's climate is being altered due to changes in the atmosphere known as the greenhouse effect. The greenhouse effect is particularly significant in the polar regions of the Arctic and Antarctic, where much of the world's fresh water is frozen in huge quantities of ice. On the Antarctic Peninsula, temperatures have been recorded as increasing two to three times more quickly than the rest of the Earth.

How ice melts in Antarctica

Hardly any ice melts in the centre of Antarctica because it is too cold.

Ice travels from inland Antarctica to the coast via glaciers. This continual process transfers ice along the glacial rivers, eventually reaching the ocean. When icebergs break away from glaciers and float into the ocean, most of the melting ice is taken from underneath the iceberg. It is difficult to tell how much ice melts from icebergs because we cannot see it.

The melting of ice in Antarctica is a natural part of the Earth's water cycle. Problems would arise if  there were more ice melting than there was snow falling. If this were to happen, a lot of water would be added to the world's oceans and the sea levels would rise. This would create problems for countries that are very close to sea level, as they would be flooded.

Melting ice and rising waters

Temperatures are rising quickly on the Antarctic Peninsula because the land in this area is more closely surrounded by ocean. This means that average coastal temperatures here are around - 5oCelsius, while temperatures in the middle of the continent are around - 37oCelsius. This means that ice can melt more easily in the Peninsula region. Temperatures there can even rise above 0oCelsius in the summer months, which is much warmer than in other parts of Antarctica. Some ice shelves on the Antarctic Peninsula have melted and floated away on the ocean.

See images 1, 2, 3 and 4
 

Climate change

The Earth has always experienced changes in its climate. One of the most dramatic climate changes take place during ice ages and the thaw that follows. The main difference between past climate changes and the climate change that is happening in modern times, is the human cause and speed of the changes. Humans have increased the amount of greenhouse gases in the atmosphere.

Greenhouse gases

The greenhouse effect is a natural process that warms the Earth. It is the process where warmth from the sun is trapped in gases in the lower atmosphere of our planet. Without the greenhouse effect, the world would be a much colder place.

One of the gases that traps the warmth from the sun is carbon dioxide. By burning fossil fuels and timber from forests, humans have created more carbon dioxide than the Earth needs. The extra greenhouse gases in our atmosphere are making the world a warmer place and are contributing to the ice melting in Antarctica.

Hole in the ozone layer

The ozone layer surrounds the Earth and absorbs harmful ultraviolet radiation from the sun. In the 1980s, scientists discovered that a hole in the ozone layer was beginning to appear above Antarctica. The hole was caused by chlorine found in chlorofluorocarbons (CFCs), which were used in aerosol sprays and fridges. The CFCs floated in the atmosphere and made their way down to Antarctica. In the winter months, the chlorine attached itself to ice found in the polar atmosphere. In spring, the ice particles melted and the chlorine reacted with the ozone, creating the hole in the ozone layer.

These days, CFCs are much less common. It is hoped that the hole in the ozone layer will become smaller with time. See image 5 and animation

The effect on Antarctic ecosystems

The burning of fossil fuels causes large amounts of heat to remain trapped in the atmosphere. This heat acts as a suffocating blanket, leading to increases in temperatures around the globe.

Evidence of the damage caused by rising temperatures can be seen in Antarctica, for example, the declining population of the Adelie penguins. Penguins dive into cracks in the sea-ice to catch their food in winter. The decline in these populations stems from the decline in the penguin's primary food source, crustaceans called Antarctic krill.

Less sea-ice results in less algae, which is the primary food source for krill larvae in winter. Evidence suggests that the krill are either not surviving or not fully developing as the winters become warmer. As a result, the entire Antarctic food chain suffers severe consequences. The baby krill are pivotal in the  Antarctic food chain. Without krill there are no whales or seals. If global warming continues, Antarctic ecosystems will suffer devastating effects as the decrease of sea-ice result in less algae, and therefore less krill and ultimately less wildlife in Antarctica.


Chapters: Weather Global warming Plants and animals

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Question 1/5

1. The large and growing amount of greenhouse gases in the atmosphere is mainly due to:

plant decay

volcanic eruptions

human activity

earthquakes

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