The Earth is surrounded by a thin blanket of gases, known as the atmosphere. 

Contained in the atmosphere are a number of gases including carbon dioxide, methane and water vapour. 

These are known as greenhouse gases because they trap heat from the Sun, warming the Earth. 

This is a natural process, and without it the Earth would be too cold to support life, and we wouldn't be here.  So in itself, the greenhouse effect is a very good thing, but over the last few hundred years we have upset this delicate process that has taken millions of years to reach a balance.

Across the world we use 12 times as much energy as was used at the start of the 20th century.  This is because of the birth of motorised transportation, consumer electronics and a rapidly growing population.  Most of our energy in the UK is made by burning coal, oil and gas in power stations, boilers and vehicles.  These fuels are known as fossil fuels, because they are made from the remains of prehistoric animals and plants.  When they were alive, these creatures took carbon dioxide from the air, releasing oxygen and keeping most of the carbon stored in their bodies. 

The carbon is the bit that burns well, and when we burn it we once again release carbon dioxide back into the atmosphere.  This doesn't seem to be much of a problem as it is replacing the carbon dioxide that originally came from the atmosphere, though the difference is that the carbon that we have released in the last 200 years took millions of years to form.  The speed at which we are releasing it back into the air is causing disruption, as the atmosphere isn't used to dealing with such quick changes.

Have a look at the video below from the Climate Challenge Project (courtesy of www.youtube.com), to find out a bit more about the causes of man-made climate change.  Press the play arrow to watch the video.

  Climate change evidence - worldwide