WHAT IS THE CAUSE?

Global warming is caused by increases in levels of greenhouse gases attributable to human activities.
Carbon dioxide is the main contributor responsible for 80% of emissions from industrialised countries. The gas is released into the atmosphere primarily from burning fossil fuels: oil, petrol and natural gas. A growing population coupled with increasing demands on transport and energy, has led to emissions increasing at dramatic rates.
Other greenhouse gases which arise from a range of industrial and agricultural sources are:

• Methane
• Nitrous oxide
• Hydrofluorocarbons (HFCs)
• Perfluorocarbons (PFCs)
• Sulphur Hexafluoride (SF6)

Combined, these greenhouse gases absorb infrared radiation in the atmosphere and thus change the dynamic balance between energy arriving from the sun and energy escaping.
For further information: UN Framework Convention on Climate Change (UNFCCC) - Climate Change Information Kit.