Climate change causes
The Earth is surrounded by a blanket of gases called the atmosphere, which enables the planet to sustain life by keeping temperatures largely in balance over long periods and allowing all living organisms to breathe.
Atmospheric gases are mainly comprised of nitrogen (79 per cent), oxygen (21 per cent) and carbon dioxide (0.03 per cent), with very small amounts of other gases such as argon and krypton.
The climate has changed many times over millions of years − changes brought about by the sun's activity, continental drift, the nature of the oceans and the composition of the atmosphere.
Impact of human activity
Now, human activity such as clearing forests, agricultural activity, and burning fossil fuels have all added to the concentrations of greenhouse gases, particularly carbon dioxide (CO2) in the atmosphere
As we burn fossil fuels − coal, oil and gas − to heat and light our homes, to power industry and by using vehicles and planes to get from place to place, the carbon which these fuels are largely made from is released into the atmosphere as CO2 emissions.
This additional CO2 increases the blanket effect of the atmosphere, trapping in heat, which would normally escape to space, and as a result our global atmosphere is beginning to warm. The 20th century saw a global warming of 0.6o centigrade (C). (For comparison the last ice age was brought on by atmospheric cooling of between 2oC and 5oC
The Earth's climate has experienced natural changes over millennia but this global atmospheric warming brought about by additional CO2 release is beginning to change the Earth's climate in ways which have never been experienced by humankind.