The new evidence could mean that humans are having an even greater impact than was believed on the carbon dioxide levels which regulate the earth’s temperature, and may change scientists’ minds about which planets could sustain life.
The findings are likely to surprise many in the scientific community, said biologist Dr Kelly Redeker from the University of York, who led the research team.
Previous laboratory research has suggested that bacteria can stay alive at extremely cold temperatures, but the new study is the first to have observed bacteria in a polar environment.
Working on sites in the Arctic and Antarctic, the researchers examined snow in is natural state and sterilised it using UV lamps. They discovered unexpected levels of methyl iodide, a gas known to be produced by marine bacteria, in the untouched snow.
Dr Redeker said the findings would challenge assumptions that gasses trapped in the ice had been rendered sterile, and could “lower the baseline” on the effect human activity had caused to CO2 levels.
“It could mean that we’ve actually enhanced the impact on the atmosphere a little bit more than we thought we had already,” he said.
But the ability of frozen matter to sustain life may have implications beyond the earth, he added.
“The fact that we have observed metabolically active bacteria in the most pristine ice and snow is a sign of life proliferating in environments where you wouldn’t expect it to exist.
“This suggests we may be able to broaden our horizons in thinking about which planets are capable of sustaining life,”
He said Mars, a planet that had once been substantially warmer than it was now, could be capable of having sustained life that had been “frozen in time”.
“It’s possible that it could support some kind of historic life that developed back when it was a nicer place to live. If life was generated in the past, it might still persist today in frozen environments,” he said.
With more research, astrobiologists working to identify planets in the so-called “Goldilocks zone”, whose temperatures could allow for the presence of water, may be able to extend the search for habitable parts of the universe.
Dr Redeker said: “One of the more interesting aspects is the idea that even in effectively frozen environments the nutrient-poor life is still capable of metabolizing and getting on with the business of life.”