They came to document global warming and shrinking polar ice caps – but now they’re desperately waiting for the US Coast Guard to rescue their ship after it got stuck in record-breaking Antarctic ice.

The Coast Guard icebreaker Polar Star left Australia Sunday and is steaming toward Antarctica to rescue crew members from the scientists’ Russian ship – and a Chinese vessel that came to its aid and also got stuck.

The drama began Christmas Eve when the Russian MV Akademik Shokalskiy – carrying scientists and eco-tourists on a mission to study global warming – got trapped in sea ice.

A Chinese icebreaker – the Xue Long or Snow Dragon – came to the Russian ship’s aid, sending its helicopter to ferry 52 of the scientists and passengers to the Aurora Australis, an Australian icebreaker.

But then the Xue Long also got stuck – and the Australian government called on the US to come to the rescue the crews of the Russian and Chinese ships.

“The US Coast Guard stands ready to respond to Australia’s request,” Vice Adm. Paul F. Zukunft, commander of Coast Guard Pacific Area, said in a statement. “Our highest priority is safety of life at sea, which is why we are assisting in breaking a navigational path for both of these vessels.”

The Polar Star will take about a week to reach Commonwealth Bay, where the two ships are stranded, Australia’s Maritime Safety Authority said.

But the crews reportedly have plenty of food and water – and spent time waddling around ice flows with curious penguins.

The scientists and tourists remained safely aboard the Aurora Australis, which did not get stuck but is staying in the vicinity as a precaution until the Americans arrive.

The Seattle-based Polar Star – a 399-foot, 13-ton beast whose engines can deliver 75,000 horsepower – is the Coast Guard’s only heavy-duty polar icebreaker.

With a specially designed hull, it can crash through 6 feet of ice while sailing at three knots, and break through a two-story wall of ice by backing up and ramming.

There was more winter sea ice at the site near the South Pole last year than in any year since record-keeping began in 1978, according to National Geographic.