Whilst natural climatic changes have always occurred over millions of years, the 'climate change' we are witnessing today and which is causing global warming is predominantly due to human activity. These changes have taken place in the last hundred years and at an unprecedented rate. People are causing the change by burning nature's vast stores of coal, oil and natural gas to fuel their activities. The burning of fossil fuel releases billions of tonnes of greenhouse gases into the atmosphere every year, the main one being carbon dioxide (CO2). This, together with other man-made greenhouse gases, such as methane and chlorofluorocarbons (CFCs) traps the Sun’s radiation within the troposphere much like a blanket causing it to heat.

If current trends continue, we will raise atmospheric CO2 concentrations to double pre-industrial levels during this century. That will probably be enough to raise global temperatures by around 2 - 5°C.