The Antarctic Ice Sheet may be a major source of the potent greenhouse gas methane. Old organic matter frozen beneath it may have been converted to methane by micro-organisms living there under oxygen-deprived conditions, and as the ice melts, the methane will be released.
Planetary scientist Slawek Tulaczyk says, "It is easy to forget that before 35 million years ago, when the current period of Antarctic glaciations started, this continent was teeming with life. Some of the organic material produced by this life became trapped in sediments, which then were cut off from the rest of the world when the ice sheet grew. Our modeling shows that over millions of years, microbes may have turned this old organic carbon into methane."
He estimates that 50% of the West Antarctic Ice Sheet (1 million square kilometers) and 25% of the East Antarctic Ice Sheet (2.5 million square kilometers) overlies pre-glacial sedimentary basins containing about 21,000 billion metric tons of organic carbon. That’s bad news for climate change.
Researcher Jemma Wadham says, "Our laboratory experiments tell us that these sub-ice environments are also biologically active, meaning that this organic carbon is probably being metabolized to carbon dioxide and methane gas by microbes."
Tulaczyk says, "Our study highlights the need for continued scientific exploration of remote sub-ice environments in Antarctica, because they may have far greater impact on Earth’s climate system than we have appreciated in the past."