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By Root 2167 0

expensive than either of those two problems are the damages caused by salt corroding infrastructure, including roads, railroads, airfields, bridges, buildings, water pipes, hot water systems, rainwater systems, sewers, household and industrial appliances, power and telecommunication lines, and water treatment plants. Overall, it is estimated that only about a third of Australia’s economic losses arising from salinization are the direct costs to Australian agriculture; the losses “beyond the farm gate” and downstream, to Australia’s water supplies and infrastructure, cost twice as much.

As for the extent of salinization, it already affects about 9% of all cleared land in Australia, and that percentage is projected under present trends to rise to about 25%. Salinization is currently especially serious in the states of Western Australia and South Australia; the former state’s wheat belt is considered one of the worst examples of dryland salinization in the world. Of its original native vegetation, 90% has now been cleared, mostly between 1920 and 1980, culminating in the “Million Acres a Year” program pushed by the Western Australia state government in the 1960s. No other equally large area of land in the world was cleared of its natural vegetation so quickly. The proportion of the wheat belt sterilized by salinization is expected to reach one-third within the next two decades.

The total area in Australia to which salinization has the potential for spreading is more than 6 times the current extent and includes a 4-fold increase in Western Australia, 7-fold increase in Queensland, 10-fold increase in Victoria, and 60-fold increase in New South Wales. In addition to the wheat belt, another major problem area is the basin of the Murray/Darling River, which accounts for nearly half of Australia’s agricultural production but which now gets progressively saltier downstream towards Adelaide because of more salty underground water entering and more water being extracted for irrigation by humans along its length. (In some years so much water is extracted that no water is left in the river to enter the ocean.) That salt input into the Murray/Darling arises not just from irrigation practices along the river’s lower reaches but also from the impact of increasingly extensive industrial-scale cotton farming along its headwaters in Queensland and New South Wales. Those cotton operations are considered Australia’s biggest single dilemma of land and water management, because on the one hand cotton by itself is Australia’s most valuable crop after wheat, but on the other hand the mobilized salt and applied pesticides associated with cotton-growing damage other types of agriculture downstream in the Murray/Darling Basin.

Once salinization has been initiated, it is often either poorly reversible (especially in the case of dryland salinization), or prohibitively expensive to solve, or solutions take a prohibitively long time. Underground rivers flow very slowly, such that once one has mobilized salt through bad land management, it may take 500 years to flush that mobilized salt out of the ground even if one switches overnight to drip irrigation and stops mobilizing further salt.

While land degradation resulting from all those causes is Australia’s most expensive environmental problem, five other sets of serious problems deserve briefer mention: those involving forestry, marine fisheries, freshwater fisheries, freshwater itself, and alien species.

Apart from Antarctica, Australia is the continent with proportionately the least area covered by forests: only about 20% of the continent’s total area. They used to include possibly the world’s tallest trees, now-felled Victorian Mountain Ash, rivaling or topping California Coast Redwoods in height. Of Australia’s forests standing at the time of European settlement in 1788, 40% have already been cleared, 35% have been partly logged, and only 25% remain intact. Nevertheless, logging of that small area of remaining old-growth forests is continuing and constitutes yet another instance of mining the