TIPPING POINT?
LOOKING ACROSS THE windswept plateau of World Heritage-listed Macquarie Island in December 2008, ecologist Dana Bergstrom realised something was seriously wrong.
“It was Christmas, and I was in alpine tundra,” recalls Dana, now head of Biodiversity Conservation with the Australian Antarctic Division’s Environmental Protection Program. “Everything should have been greening up. The cushion plants there go brown during winter, then turn green in spring–summer. But lots were still brown and some appeared dead.”
Individual Macquarie cushions usually live hundreds of years. It’s a keystone plant species on the plateau, meaning it’s integral to much of the life on the Australia-governed subantarctic island, located in the Southern Ocean, between Tasmania and the Antarctic continent.
Research by Dana and her island colleagues ultimately identified that protracted and unprecedented dry conditions caused by climate change were behind the demise of the cushion plant and the ecosystem it defined. “The plateau had been losing water in summer, with records showing that for 17 straight years more water was going out of its soil than was being replaced by rain,” says Dana, explaining that by the time moist conditions returned, disease had spread through the surviving cushion plants. Suddenly the species was critically endangered, and Macquarie’s scientists watched helplessly as the plateau’s ecosystem collapsed as a result.
Then came reports of something similar happening at Casey Station, one of Australia’s Antarctic mainland research stations. There, a collapse was also being seen, in the ecosystem based on moss beds – known as the Daintree of the South, because, like tropical rainforest, it supported a particularly high level of biodiversity. “Was this happening elsewhere across Australia?” Dana says was the obvious question.
The distressing answer came last February via a scientific paper accompanied by a 101-page detailed report compiled, with the support of the Australian Academy of Sciences, by Dana and 37 other ecologists and climate change experts. Most have
