Life in liquid carbon dioxide
Well, ok, perhaps it’s not life really in liquid carbon dioxide, but as you’ll see it’s pretty close. The study of extreme environments on Earth plays a big role in our expanding knowledge about places that support life but are radically different from the sunny, temperate, beer swilling, tea drinking surroundings we find ourselves in. As such these may represent good analogs to certain spots on worlds like Mars, Europa, Enceladus, or even further afield. Some of the most remarkable and provocative discoveries of extreme conditions have been those around deep ocean hydrothermal vent systems. Often located on or near to the planet-straddling mid-ocean volcanic ridges these are places where water has been siphoned into the sub-seafloor, superheated and enriched with all manner of soluble compounds (like metal sulphides, which are very bad for our delicate constitutions but just the stuff for chemoautotrophic organisms) before being squirted back out into the chill marine environment at depths of over a kilometer. Down here the ambient temperature is about 3 Celsius, and pressures can be hundreds of times that at the Earth’s surface. As the chemically rich water, often at temperatures of over several hundred degrees, sprays out into this dark cold environment it not only quickly deposits minerals but it provides oases for some of the most bizarre and unexpected ecosystems we have discovered. From extremophilic archaea and bacteria, to their symbiotic relationship with creatures like tube-worms, these locations flourish in the abyssal gloom.