Global warming is the rapid and continued increase of the Earth's surface temperature. During the last century the Earth warmed by 0.8°C. Now the Intergovernmental Panel on Climate Change (IPCC) is projecting that global surface temperatures are likely to increase by 1.1 to 6.4 °C this century. Already nineteen of the hottest 20 years on record have occurred since 1980 with 2005 being the hottest year in recorded history while the east coast of Australia had its warmest May on record in 2007.

This warming is attributable to human activities that increase the levels of greenhouse gasses (GHGs) in our atmosphere. A natural amount of GHGs are essential for life on Earth, it keeps our planet at just the right temperature by letting sunlight through but retaining only some of the heat. The increased concentration of GHGs in the atmosphere reduces the amount of the sun's warmth that is reflected back into space causing the Earth to become warmer.

The current concentrations of GHGs in the atmosphere are now substantially higher than any time in the last 650,000 years. The increase of GHGs in our atmosphere was kick-started with the industrial revolution, which since the 1850s has largely increased the output of the key GHGs, carbon dioxide, methane and nitrous oxide. At present, atmospheric concentrations of carbon dioxide have increased by over 30% and methane by over 150% above pre-industrial levels and are projected to rise by over 10% every 20 years.

GHGs come from a variety of sources, the burning of fossil fuels from industry and transportation, methane from livestock and paddy rice farming, CFCs in refrigeration, construction of buildings, the making of cement and deforestation. Three quarters of GHG emissions in the last 20 years have come from fossil fuel burning with the remainder coming largely from deforestation. Aviation is responsible for an estimated 3% of global GHG emissions but is expected to increase in the future.

Australia emits about 5 million tonnes of GHGs annually, which equates to less than 1% of the global total. Per capita Australians produce about 25 tonnes of carbon dioxide per year, one of the world's highest levels. Australia consumes about 26 billion litres of fuel a year and emits approximately 71 million tonnes of carbon dioxide. Our heavy reliance on fossil fuel for energy and road transport is the major factor in contributing to the high per capita emissions.

Roughly 70% of man made emissions of carbon dioxide in Australia are caused by fossil fuel burning, the remaining emissions are mainly due to land use change, in particular deforestation. Half of Australia's forests and three quarters of its rainforests have been cleared and over 90% of old growth forests have been logged.

Global warming is unstoppable because of past and current emissions. After 150 years of unprecedented industrial growth, climate change has real momentum and it will continue to affect the earth for centuries to come even if GHG emissions were stopped tomorrow. As a global community we have to reduce our GHG emissions as significantly and as quickly as possible to avert a serious catastrophe. We need governments to make the mitigation of global warming a priority but most are failing to make any serious effort.

Thankfully as individuals we can do something positive to help. First we need to reduce our own greenhouse gas emissions as well as making informed decisions on the products we buy. Have a look at the "Reducing your impact" page to see a list of ways you can reduce your carbon footprint. Coolplanet can also conduct an energy assessment on your home or business and then, if you choose, offset the remaing emissions by funding carbon reduction projects. By taking this initiative, together we can help make global action on climate change a reality.