More than 12,000 kilometres of Australia's sandy beaches are threatened by coastal erosion by the end of the century, with greater losses predicted if greenhouse gas emissions remain high.

The projections, made by European researchers and published in Nature Climate Change on Tuesday, used satellite data that tracked shoreline change from 1984 to 2015. They found a "substantial proportion" of the world's sandy coastline is already eroded, a trend that could worsen as climate change pushes up sea levels.

Australia's coastline has already seen significant areas of retreat in recent years, such as at Inverloch, in Victoria. Credit:Google News Lab

Under a "moderate" effort to curb emissions - with carbon pollution peaking at 2040 and then declining - at least 12,324 kilometres of Australia's sandy coast will be threatened with erosion by 2100. That tally is the most of any nation, and would amount to about 40 per cent of the country's sandy beaches.

Should greenhouse gas emissions continue to rise through the century - the so-called 8.5 Representative Concentration Pathway - Australia's sandy coastline at risk increases to 15,439 kilometres, the paper said.