Desertification and deforestation, for example, are allowing more dust and tiny particles called aerosols to enter the atmosphere, which reflect more solar radiation back into space. Sulphur dioxide emitted by fossil fuel combustion contributes to the cooling of the atmosphere because it forms sulphate aerosols which reflect solar radiation. Sulphate aerosols from volcanic eruptions may also have a similar cooling affect. These aerosols scatter sunlight, reducing the amount that reaches the earth, and also absorb infra-red radiation reflected from the ground. Some aerosols including the sulphates from power stations, are good condensation nuclei, encouraging the formation of clouds that shield the earth from sunlight.
Sulphate aerosols affect climate mainly in the northern hemisphere.
Torok et al. The NSW EPA contracted the Victorian EPA to undertake an inventory of greenhouse gas emissions and sinks in NSW for 1990 with projections for the year 2000. Greenhouse gas emissions in NSW for 1990 totalled 174 million tonnes, expressed in terms of carbon dioxide equivalent. Emissions of the different greenhouse gases and their respective carbon dioxide equivalents are presented in table 4 and the percentage contribution of the individual gases in figure 4 . A detailed summary of the three main greenhouse gases is provided in table 5 .