The Greenhouse Effect

Here is an article on Australia's Greenhouse gas emissions. An interesting figure to note that nearly 69% of Australia's Greenhouse is producing by human activities

The Greenhouse Effect.

Greenhouse gases are a natural part of the atmosphere. They trap the sun's warmth, and maintain the earth's surface temperature at a level necessary to support life. Human actions are increasing the concentrations of these gases in the atmosphere, creating the prospect of global climate change.

Water vapour is the most important greenhouse gas, but human activities make little direct impact on the amount of water in the atmosphere. Human activities have a significant effect on carbon dioxide that comprises 68.4% of Australian Greenhouse gas emissions, methane comprising 25% and nitrous oxide, 6.4%.

Australia’s net greenhouse gas emissions for 1999 were 458.2 million tonnes of carbon dioxide equivalents, excluding land clearing. Land clearing is accounted for separately due to high levels of uncertainty associated with the estimates. Emissions from land clearing are a result of burning cleared vegetation, decay of unburnt vegetation and from soil disturbance which are offset by carbon sequestration due to regrowth of vegetation on previously cleared land. It was estimated that net emissions from land clearing were 71.7 million tonnes of carbon dioxide in 1999.

Carbon dioxide emissions resulting from direct human activities have significantly altered the global carbon cycle. Carbon dioxide is major type of greenhouse gas released in Australia. In 1999 some 313.5 million tonnes were released of which 256.9 million tonnes resulted from the creation of energy. Electricity generation alone contributed 171.2 million tonnes, with transport the next largest source with 69.5 million tonnes.

Methane makes the next biggest contribution to greenhouse gases. Of the 114.4 million tonnes of methane emitted, agriculture contributed 61.6% of this.

Of the 29.3 million tonne of carbon dioxide equivalents of nitrous oxide emitted, the majority of these emissions were from agricultural soils due to adding fertiliser or burning savannas.

Forest growth provided a CO2 sink of 75.8 Mt, more than offsetting 52.8 Mt emissions from harvesting.