Life has been discovered 1.5 miles beneath the West Antarctic Ice Sheet, in a lake that has not been disturbed for millions of years.
Scientists from Montana State University and the University of Tennessee reported their findings in the journal Nature, saying they found microorganisms that convert ammonium and methane into energy for growth.
The lake they were found in has not seen sunlight or been exposed to wind for millions of years.
Lead author Brent Christner said: "It's the first definitive evidence that there's not only life, but active ecosystems underneath the Antarctic ice sheet, something that we have been guessing about for decades. With this paper, we pound the table and say, 'Yes, we were right.'"
John Priscu, chief scientists of the project, added: "We were able to prove unequivocally to the world that Antarctica is not a dead continent."
Priscu said he was not completely surprised to discover life in such a remote area – he had published two manuscripts over 10 years ago describing how microbial life could thrive under Antarctic ice. However, he said he was excited to find out how the microbes function without sunlight in such cold conditions.
Findings showed the organisms are archaea – one of three domains of life. The others are bacteria and eukaryote.
Many of the organisms found use energy in the chemical bonds of ammonium to fix carbon dioxide and drive metabolic processes, while another group uses energy and carbon in methane to survive. The ammonium and methane is likely from the breakdown of organic matter from hundreds of thousands of years ago, the authors said.
Researchers believe their findings have implications for life in other extreme environments, including space.
Jill Mikucki, one of the researchers on the study, said: "Because Antarctica is basically a microbial continent, exploring below its thick ice sheet can help us understand how life has evolved to survive in cold darkness. I hope our findings motivate new research on the role of these extreme microorganisms in the function of our planet and other icy worlds in our solar system."