Bacteria in volcanic mineral (Photo: Stefan Weiss)Scientists have released a study about a little-known ecosystem: the ground beneath our feet. Known as the "subterranean biosphere", it is almost twice the size of all the world’s oceans combined. It is difficult to imagine living things surviving inside rocks deep beneath the Earth's surface. There is no light, barely any food, and, a few kilometres down, intense pressure and heat. But scientists say that this ecosystem is, in fact, teeming with life. Researchers say it contains many billions of tonnes of micro-organisms—equivalent to between hundreds of times the combined weight of every human (around 7.7 billion of us) on the planet.
Deep-ocean rock containing archaea-eating worm (A.Thurber)The team at the Deep Carbon Observatory combines 1200 scientists from 52 countries. Samples were taken from boreholes more than 5 kilometres (3 miles) deep and at undersea drilling sites. The researchers estimate that the weight of micro-organisms—between 15 and 23 billion tonnes—beneath the Earth's surface dwarfs the amount of life existing on top of it. The results suggest that 70% of Earth’s micro-organisms—bacteria and archaea—exist underground. “It’s like finding a whole new reservoir of life on Earth,” said Karen Lloyd, an associate professor at the University of Tennessee in Knoxville. “We are discovering new types of life all the time. So much of life is within the Earth rather than on top of it.”
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