What is the Greenhouse Effect?
The earth is surrounded by a layer of air about 50 kilometres thick. The lower atmosphere, called the troposphere, is about 10 kilometres thick and is the closest to Earth. This air contains gases which are important for life on our planet, such as oxygen for us to breathe, carbon dioxide which plants need to grow and other gases which help keep the earth warm.
When the heat from the Sun strikes the Earth, these gases trap some of that warmth before it can escape back into space.
The Greenhouse Effect is a good thing! Without it our planet would be so cold that nothing would be able to survive.
However, human activities are changing the greenhouse effect. Using coal-fired power stations releases large amounts of carbon dioxide into the atmosphere. Driving cars that run on petrol also puts more carbon dioxide into the air. As our population has grown and our need for more and more energy increases, the amount of greenhouse gases in Earth's atmosphere (particularly carbon dioxide) has increased dramatically. All these extra greenhouse gases result in more heat being trapped around the earth.
For many years the precise effects of this were uncertain, but we now have relatively conclusive proof that with more gases to trap the Sun's heat, the Earth's climate is changing. The planet is getting warmer! We call this global warming.
So what is the problem with that?
A rise in the Earth's temperature could seriously affect our planet's weather in a number of ways, such as:
- as water heats up, it expands and our sea levels would rise.
- higher temperatures would melt ice and snow which could make the sea level rise even more.
- some areas might receive higher rainfall than at the moment, resulting in flooding.
- other areas might receive much less rainfall, resulting in drought.
- more severe storms.
- higher temperatures could lead to an increase in the number of serious bushfires.
- animals and plants and their habitats will be affected. Some may increase in numbers some may become extinct.
- growing of crops will be affected.