Antarctica's native species are facing invasion as climate change dramatically expands the continent's ice-free zones, a new study warns.
Australian researchers say the warming climate could see ice-free areas increase by almost 25 per cent by the end of the century.
Invasive species that are already changing the ecology of sub-Antarctic islands are likely to take hold further south in newly exposed parts of the continent and may out-compete native species, some of which are found no where else in the world.
"As the climate warms and it gets milder, and there are more ice-free areas, invasive species will become able to establish themselves," says PhD student Jasmine Lee, who helped lead a new study published in the journal Nature.
"They'll probably be able to out-compete the native species, which have evolved over long periods and are very specialised."
The study, under the Australian Antarctic Program, suggests the 70,000 square kilometres that are current ice free could swell to more than 87,000 square kilometres by 2100.
Antarctica's best defence against invasive species - its extreme climate and weather - was eroding with the continent's ice cover and glaciers, Ms Lee said.
"Humans are the primary transporter of these non-native species - scientists and tourists who accidentally carry seeds in bags or on their shoes," she said.
She said one invasive grass species, poa annua, had already managed to colonise a newly ice-free part of the Antarctic Peninsula that had seen glacial retreat.
"It could out-compete the two native Antarctic plants. Those two plants are only found on the peninsula," she said.
It has also established itself on sub-Antarctic islands, where researchers are still working out how what impact it has had on native flora and fauna.
Ms Lee says there could be some opportunity for native species to move around and disperse as ice-free areas expand, but any opportunity comes with the risk of improved conditions for invaders.
"There are going to be winners and losers but more research is needed to find out which species will win and which will lose," she said.
"One of the most important things we need to do is increase biosecurity, and make sure we're not taking invasive species down there as the climate changes and makes it easier for them to survive."
Ms Lee and Australian Antarctic Division senior research scientist Dr Aleks Terauds led the team that put the research together.