SYDNEY, Australia — Antarctica could be invaded by rats, insects, and foreign plants as global warming and human intrusion has a devastating impact on the wilderness, Australian researchers say. The last untouched area of Earth is being visited by greater numbers of humans, who are unwittingly importing spores, seeds, and insects.

Experts say climate change is already encouraging the spread of one type of European grass and could help rodents colonize more clement areas, heralding disaster for vast colonies of ground-nesting seabirds, such as penguins.

“Antarctica is the last bastion of a pristine environment,” Dana Bergstrom of the Australian Antarctic Division — and who is also the head of an international “Aliens in Antarctica” research project — said. Alien species already have a toehold on many outlying islands. The Australian-administered territory of Macquarie Island has been overrun by mice, rats, and cats.

Norwegian reindeer introduced to South Georgia, the British territory near the Falkland Islands, overgraze natural sedges and mosses.

Particularly vulnerable to alien invasion is the Antarctic peninsula, which curls toward the southern tip of South America and where less frigid temperatures could enable rodents to establish a foothold.

To try to keep the invaders out, tourism operators require visitors to scrub their boots and ban them from taking food ashore.