Most potent greenhouse gas. Produced by bushfires and burn-offs, decomposition in rice paddies and garbage landfills, and during digestion in cattle, sheep, goats, deer and buffalo. Also released when coal is mined. Levels have more than doubled since 1850. Hard to reduce because many of the processes that produce methane are widely regarded as beneficial.
Major source is disturbance of soil for agriculture and forestry.
Also produced by use of artificial fertilisers, burning of vegetation and fossil fuels, motor vehicle emissions. Not present in atmosphere until introduction by industry in1930s. Used for refrigeration and air conditioning, as aerosol propellant and in foam manufacture. Australia is a significant contributor to global greenhouse gas emissions. In 1990, Australia ranked fourteenth in the world in total quantity of greenhouse gases released.