IndoAustralian Plate. Surrounded by the Indian and Pacific oceans, it is separated from Asia by the Arafura and Timor seas. It the sixth largest country in area after Russia, Canada, China, the United States and Brazil. It is the flattest and (after Antarctica) the driest of continents, yet it has extremes of There are rainforests and vast plains in the north, snowfields in the south east, desert in the center and fertile croplands in the east, south and south west. About one third of the country lies in the tropics. Mountain ranges run from north to south along the east coast, reaching their highest point in Mount Kosciusko (2,228 m). The western half of the continent is occupied by a desert plateau that rises into barren, rolling hills near the west coast. Mount Kosciusko
After a rapid GHG release from an initial fire to burn the original biomass, there will still be a long prolonged period, when GHG is released, as coarse roots and root branches decay. It has been estimated that clearing land would release between 17-420 times more CO 2 than the annual GHG emissions the biofuels would save by replacing fossil fuels (Farigone, 2008). Another study has concluded that converting forests and grasslands to new croplands can double the GHG emissions for 30 years (Searchinger, T. 2008). Despite the real threat to deforestation, some studies suggest that biofuels can be successfully grown on marginal lands, such as abandoned agricultural soils, saline soils and reclaimed mining areas (Reijnders, 2008). However, it is highly that biofuels demand can be satisfied only with crops grown on marginal lands. Also, currently, the legislation does not incentivise such approach.
Surface mining is used to produce most of the coal in the U.S. because it is less expensive than underground mining. Surface mining can be used when the coal is buried less than 200 feet underground. In surface mining, giant machines remove the top-soil and layers of rock to expose large beds of coal. Once the mining is finished, the dirt and rock are returned to the pit, the topsoil is replaced, and the area is replanted. The land can then be used for croplands, wildlife habitats, recreation, or offices or stores. Picture 15.2. Surface mining Underground mining, sometimes called deep mining, is used when the coal is buried several hundred feet below the surface. Some underground mines are 1,000 feet deep. To remove coal in these underground mines, miners ride elevators down deep mine shafts where they run machines that dig out the coal. Read about a visit to a real underground coal mine.
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