Rising Seas Could Cost Australia $855 Billion by 2100, Study Finds

Rising sea levels and storm surges could cost Australia at least $855 billion in economic losses by 2100, according to the first study of its kind in the country, published in the journal Scientific Reports. The research, led by University of Melbourne Professor Tom Kompas with colleagues at the Australian National University, estimates that coastal flooding could affect almost 270,000 properties and 2 million hectares (4.9 million acres) of land, including homes, farms, infrastructure and environmental assets.

The study uses an Intergovernmental Panel on Climate Change scenario called SSP2-4.5, an intermediate emissions pathway leading to about 2.7 degrees Celsius of average global warming above preindustrial levels by 2100, broadly consistent with current climate policies but well above the 1.5-degree target agreed in the Paris Agreement. Researchers mapped likely flood zones using sea-level projections, storm-surge estimates and elevation data, then estimated the value of properties and land at risk.

Every state and the Northern Territory would bear significant costs, ranging from $230.5 billion in Western Australia and $214.5 billion in Queensland to $7.9 billion in Tasmania. Queensland has the most properties at risk, with 93,157, followed by New South Wales and Western Australia. The Gold Coast alone faces $84.4 billion in projected losses, the single most exposed urban area in the country.

The modeling holds storm intensity constant, excludes erosion losses, and does not account for the possibility of a rapid collapse of ice sheets in Greenland and West Antarctica, which could bring up to 2 meters (6.6 feet) of sea-level rise by 2100. "Sea level rise may physically affect a large number of Australians, as the majority of Australians live within 50 kilometers (31 miles) of the coastline," Kompas said.

The study underpins the Climate Council's "Rising Seas Rising Bills" report. Co-author Andrew Watkins said Tropical Cyclone Alfred cost the City of Gold Coast $35 million in beach repairs alone, showing how storm surges riding on higher seas already worsen coastal flooding. Kompas said avoiding construction in the highest-risk areas and restoring coastlines are among the least costly ways to reduce future damage.