Japanese and German researchers have found billions of bacteria and other tiny organisms living in a layer of sediment which traps the CO2 under the seabed. Their survival in such a hostile natural environment suggests that something similar could be happening on other planets.
If water and CO2 are present below the surface in polar environments, says Fumio Inagaki at the Japan Agency for Marine-Earth Science and Technology in Yokosuka, "I expect that life signatures utilising chemical materials and CO2 for growth might be found."
Inagaki's team and researchers at the Max Planck Institute for Marine Microbiology in Bremen, Germany, investigated an area at the southern end of the Okinawa Trough, about 1400 metres under the East China Sea. There, hot black sulphurous fluids are vented into the water from two seabed "chimneys" known as Tiger and Lion, a stunning phenomenon captured on video by the research team. View the footage here.
The microbes were discovered 50 m south of the chimneys in samples taken from the crust of sediment covering a lake of liquid CO2. The video also shows a clear stream of CO2 bubbles escaping from the hole made by the researchers' sample corer.
This is a sight that few people have ever seen, says Kenneth Nealson at the University of Southern California in Los Angeles, US. It looks "almost surreal", he says in a commentary accompanying the research in the journal Proceedings of the National Academy of Sciences.
Inagaki hopes that his research will also help plans to dispose of climate-wrecking CO2 by injecting it into the seabed. Care needs to be taken to make sure that acidification does not damage ecosystems, he told New Scientist.
Inagaki's study should be available soon at the Proceedings of the National Academy of Sciences here.