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Environmentalists are warning a new report showing the Great Barrier Reef has bounced back five times from major "death events" doesn't mean it will survive a sixth. A 10-year-long multinational study, published in Nature Geoscience journal this week, shows the reef has suffered five major climate-related events over the last 30,000 years, but has rebounded each time. However the report's authors stress the current pressures being put on the reef, including increasing sediment runoff, rising water temperatures and influxes of pest species, are happening at a much faster rate than in the past. World Wildlife Fund's head of Oceans and Sustainable Development, Richard Leck, said there was still a chance to preserve the reef in some form, but the window for action was rapidly closing. "It sounds like hyperbole, but if you look at the science it shows a rise of over two degrees by 2050, and at that point there aren't reefs for our kids to enjoy," he said. "If you look at the signs from the last few years, we may be witnessing the beginning of the sixth extinction of the reef." Mr Leck said action on climate change could help to reduce the impact on the reef, as well as action on sediment runoff into reef catchments. But he warned a tipping point was coming which would mark a point where the reef couldn't recover sufficiently as it had in the past. The study drilled fossil cores from a number of sites along the length of the reef, finding at various times it migrated both towards the shore and out to sea at rates of up to 1.5 metres a year to adapt to rising and falling sea levels and changes in water temperature. However changes to temperature happened at the rate of a few degrees over 10,000 years, while current forecasts predict up to two degrees increase over the next century. The federal government announced this month it would spend $500 million to help restore and protect the reef in the coming years, including improving water quality. Australian Associated Press

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