Non-energy emission abatement

The other important anthropogenic greenhouse gases emitted in Australia are methane and nitrous oxide. Compared with carbon dioxide, little is known about either sources of, or possible abatement measures for these gases, particularly nitrous oxide. The most important source of methane, thought to account for about two-thirds of total emissions, is domestic livestock, principally cattle, sheep and pigs. Landfill (municipal garbage) is also an important source. Small quantities of methane are released as a result of coal mining and from the natural gas distribution system. Agricultural activities, in this case soil denitrification associated with both the application of nitrogenous fertilizers and the use of legumes in improved pastures, is thought to be the main source of nitrous oxide (Ecologically Sustainable Development Working Groups 1992). Measures which it is thought could contribute to reducing these emissions include: the use of rumen modifiers (anti-bloat capsules) with intensively reared cattle; a modest decrease in stocking rates on some pasture types used for extensively reared cattle; aerobic, rather than predominantly anaerobic treatment of piggery waste; and the optimization of application rates of nitrogen fertilizers. The ESD did not estimate the scope, let alone the cost of these measures if applied on a large scale.

Abatement of atmospheric carbon dioxide levels by increased tree growth in Australia has been analysed superficially. Over the last few years growing concern about deforestation and soil erosion stimulated a variety of government and privately supported programmes to reverse the trends of two centuries of European colonization. These programmes could perhaps stop and perhaps reverse the continuing emission of carbon dioxide previously sequestered in biomass in trees and in the soil. As such they can legitimately be seen as an important part of national activities to curb greenhouse gas emissions, although that is not the reason they were initiated. From a greenhouse perspective, therefore, they are costless measures. However, much more far-reaching tree plantation programmes would be required to make a significant contribution to offsetting carbon dioxide from energy related activities. No estimates are available yet of the possible cost and scale of such programmes in Australia.