A RICH diversity of unique plant and animal species live in World Heritage Listed Kakadu National Park. These include vast flocks of magpie geese, which congregate in millions to feed on water chestnuts growing on the floodplain of the South Alligator River. Unfortunately, this pristine northern Australian wetland now faces severe threats from climate change, feral animals and invasive weeds.
The Kakadu wetlands formed about 6000 years ago. This occurred after sea levels had stabilised, following an earlier rise of 120m at the end of the last ice age. Ironically, it could be further sea level rise that spells the end of these wetlands. Among the many effects of human-induced climate change are rising sea levels and more intense cyclones in the tropics.
About 20cm of sea level rise occurred during the 20th century. At least double that amount – and perhaps much more – is predicted for the 21st century. Both sea level rise and more intense storm surges act to increase the regularity and severity with which seawater washes through the low-lying freshwater wetlands. At the Mary River mouth, extensive earthen barrages have been built already in an attempt to hold the burgeoning tides at bay.
If emissions of greenhouse gases are not curtailed quickly and substantially, by the end of this century, the sea level rise caused by global warming will have inundated extensive tracts of Kakadu. What remains will be isolated patches of freshwater wetlands within a mire of brackish swamps and saltwater mangroves. Stripped of their prime habitat, the spectacular aggregations of magpie geese will decline and fragment. They will become an occasionally spotted curiosity, rather than a tourism mainstay.
Indigenous people will be robbed of a traditional bush food. Many other species of birds, as well as frogs, water snakes and freshwater fish will also retreat or disappear. One of Australia’s natural jewels will have lost its lustre. (Prof. Ross Garnaut, in his draft report on the economic impacts of climate change on Australia, pinpoints Kakadu as one of the areas most under threat)