WASHINGTON – The remains of life forms that thrived long ago in a temperate Antarctic have probably been converted into a large cache of methane that could be released if the ice sheet shrinks, researchers report.
A collaborative research team representing Canada, the Netherlands, the United Kingdom and the United States released the finding on August 29. The U.S. National Science Foundation, the British Natural Environment Research Council and the Leverhulme Trust were among the funders of the research.
“This continent was teeming with life” 35 million years ago, according to Professor Slawek Tulaczyk in the Earth and planetary sciences department at the University of California, Santa Cruz, and a co-author of the study. “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.”
Beneath an ice sheet as much as 1.5 kilometers thick lies the bedrock surface of Antarctica, the coldest, driest and windiest continent, surrounded by the Antarctic Ocean. When winter comes, the deep freeze can create an iced-in area that exceeds the land mass of the continent.
The continent is divided by the Transantarctic Mountains, with ice sheets on each side. The research team estimates that half of the West Antarctic Ice Sheet and one-quarter of the East Antarctic sheet cover pre-glacial sediment that could contain 21 trillion metric tons of organic carbon.
“Our laboratory experiments tell us that these sub-ice environments are also biologically active,” said Jemma Wadham, study co-author from the University of Bristol School of Geographical Sciences, “meaning that this organic carbon is probably being metabolized to carbon dioxide and methane gas by microbes.”
If the researchers are correct, shrinking of the Antarctic ice sheet could release the methane into the atmosphere, boosting the level of greenhouse gas emissions that are already contributing to climate change, and also causing the diminution of glaciers and sea ice in the northern reaches of the planet.
“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,” Tulaczyk said.