The Earth's atmosphere
CO2 and other greenhouse gases occur naturally in our atmosphere. They provide a protective layer around the planet and retain some of the Sun's heat on Earth. Surplus heat is radiated back into space. This protective layer keeps the average temperature on Earth at a pleasant 15°C.
Climate change
Since the Earth came into being some 5 billion years ago its climate has been changing constantly, with changes tending to occur very gradually. However, temperatures have risen far more rapidly over the past 50 years than ever before. This is because the concentration of CO2 in the atmosphere has increased very sharply, caused by factors such as the burning of fossil fuels and deforestation. As a result more heat is being held 'captive' in the atmosphere, causing the temperature on Earth to rise rapidly.
Effects
The effects of the rise in temperature are already noticeable. Entire areas have become unsuitable for agriculture because of prolonged drought, for example, with all its consequences. Climate models predict that the North Pole will be completely ice-free in the summer of 2013. The changing climate will have major consequences for mankind, while many animal and plant species will become extinct. Climate change is nothing new. However, the speed at which it is now occurring, in combination with the enormous population density on our planet, means the effects on society will be drastic.
Fore more information about climate change also see: