![]() Meanwhile, environmentalists fear that when climate change hits, the extra water promised to make rivers healthy may be the first thing to go. Extra water will be available if the State Government decides to end logging in catchments (it is now investigating the practice). But any Government that takes water from farmers to give to a city is asking for political trouble. Some observers say Melbourne must look to water from north of the Great Dividing Range. The Bracks Government has ruled out building a new reservoir because it is too costly and environmentally destructive. And as water resources shrink, the city's thirst expands. In a warmer world, this is expected to increase to 12 by 2020 and 12 to 18 by 2050. ![]() Melbourne, on average, experiences nine days of 35 degrees or more a year. And then there's the frequency of hot days. ![]() As the mercury rises, so does evaporation. Temperatures in Australia have already increased 0.67 degrees since 1910. Under the CSIRO's worst case, average temperatures could rise another 2.5 degrees by 2050. In other words, a significant amount of rain will fall in Bass Strait and on Tasmania, reducing run-off to Melbourne's reservoirs. But Roger Jones, a co-author of the report and a senior research scientist with the CSIRO's atmospheric division, says modelling shows the "whole system moves poleward" under climate change. The system relies on westerly rain belts. They act like sponges, soaking up autumn and winter rains until the water runs off into the reservoirs. Melbourne's water catchments are forested mountain ranges in the city's east. But in the simulations of future climate patterns by scientists from the CSIRO and Bureau of Meteorology, Victoria, NSW and the south of Western Australia all experience less run-off to water storages. Across the world, the climate will change differently. Climate change is caused by global warming - when carbon dioxide from burning fossil fuels prevents the Earth's heat radiating into space.
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