Posted 13th May 2001

Global Warming Forecast to Hit Australia Hard Australia will be hotter and drier in coming decades according to the latest climate change estimates of the Commonwealth Scientific Industrial Research Organization (CSIRO), the government's research branch. "Rising concentrations of greenhouse gases are the culprit," says Dr. Peter Whetton from CSIRO Atmospheric Research. CSIRO today released its projections of the likely extent of climate change in Australia and the expected impacts across the country. Greenhouse gases such as carbon dioxide and methane form a blanket in the upper atmosphere trapping the heat of the Sun close to the Earth where it warms the planet more than it has been warmed for thousands of years. The World Meteorological Organization (WMO) said most of the last decade has been warmer than usual. "The year 2000 was much like those of the 1990ís, some areas of the globe experienced extreme heat, extreme cold, extreme rainfall and extreme drought while many others experienced near normal conditions, but when averaged together the global climate continues to be warmer than normal," the WMO said last December. The changing climate is likely to have a profound effect on Australia, with many winners and losers. "Warmer conditions will produce more extremely hot days and fewer cold days," says Dr. Whetton. "Natural ecosystems most at risk are coral reefs, alpine ecosystems, mangroves and wetlands." Also under threat are tropical forests, savannas, deserts and native grasslands. Over most of the island continent, annual average temperatures will be 0.4 to two degrees Celsius greater than 1990 by 2030. By 2070, average temperatures are likely to increase by one to sixdegrees Celsius. The temperature ranges quoted indicate the scientific uncertainty associated with the projections.

Greenpeace Australia calls the CSIRO report "devastating" and has staged a protest against the country's first shipment of shale oil which the group calls "Australiaís worst new source of greenhouse pollution." Five Greenpeace swimmers and divers were arrested trying to stop the oil carrier Probo Emu from loading the first shipment of oil from the experimental Stuart Oil Shale Project, at Gladstone, next to the Great Barrier Reef World Heritage Area. Greens Senator Bob Brown is part of the protest. He says, "Climate change threatens us all. Our scientists are telling us we need to act, yet the Howard government is wasting $240 million of taxpayers money to prop up the shale oil industry. If we want to save the climate we need to shut this industry down and switch to clean energy. "The warming won't be the same everywhere," Dr. Whetton says. "There will be slightly less warming in some coastal areas and Tasmania, and slightly more warming in the northwest." Southwestern Australia can expect decreases in rainfall, as can parts of southeastern Australia and Queensland. Wetter conditions are possible in northern and eastern Australia in summer and inland Australia in autumn.

In areas that experience little change or an increase in average rainfall, more frequent or heavier downpours are likely. Conversely, there will be more dry spells in regions where average rainfall decreases. "We may also see more intense tropical cyclones, leading to an increase in the number of severe oceanic storm surges in the north. Rises in sea level would worsen this effect," says Dr. Whetton. Sea level is likely to rise at a rate of between 0.8 and eight centimeters per decade, reaching nine to 88 centimeters above the 1990 level by the year 2100. "Evaporation will increase over most of the country. When combined with changes in rainfall, there is a clear decrease in available moisture across the country," Dr. Whetton predicts. "A better understanding of the likely impacts of climate change can contribute to adaptation strategies designed to minimize adverse impacts and optimise benefits," says Dr. Whetton. "Natural systems have little opportunity to adapt to climate change. Higher temperatures and lower rainfall will be a threat. Climate change and sea level rise will add to the vulnerability of many of Australia's wetlands." Higher carbon dioxide concentrations will increase plant productivity and the efficiency with which plants use water.

A moderate rise in temperature will increase plant growth in temperate areas but may reduce it in the north. Warmer conditions will reduce frost damage to many crops. But, fruit trees need cold weather to set fruit, so some fruit yields may decline. Wheat yield will rise with warmer conditions if rainfall doesn't change. A rainfall decline of 20 percent with temperature increases of more than one degree Celsius will lower yield. "The net effect on agriculture will be a trade-off between the positive impact of higher carbon dioxide and the negative effect of lower rainfall and higher temperatures," says Dr. Whetton. Forests will benefit from a carbon dioxide enriched atmosphere, but gains may be offset by warmer conditions. "Some tropical pests, like the Queensland fruit fly, may spread southwards. Other temperate pests, like the light brown apple moth, may move to cooler areas," he says. "We're also likely to experience more water shortages and less snow." CSIRO's new projections incorporate findings of the Intergovernmental Panel on Climate Change. CSIRO issued its last climate change projections in 1996. These new projections suggest a greater temperature increase than was proposed in the past. Rainfall changes are similar in direction but greater in magnitude than those released five years ago. For Greenpeace climate campaigner Shane Rattenbury the issue is simple. "If we want to protect Australia from the devastating floods, droughts and rising temperatures that the CSIRO has predicted, this dirty fossil fuel industry must be stopped."