Earth is far more alive than we previously thought, according to "deep life" studies that reveal a rich underground ecosystem beneath our feet that is almost twice the size of all the world's oceans. Despite extreme heat, no light and intense pressure, scientists estimate it has between 15 billion and 23 billion tonnes of microorganisms. "It's like finding a whole new reservoir (储藏) of life on Earth, " said Karen Lloyd an associate professor at the University of Tennessee.
Results suggest 70 percent of Earth's bacteria and archaea exist in the subsurface. One organism found 2.5 kilometers below the surface has been buried for millions of years and may not rely at all on energy from the sun. Also, the methanogen (产甲烷菌) has found a way to create methane in this environment, which the methanogen may not use to reproduce or divide, but use to replace or repair broken parts. Lengths of their lives were completely different. Some microorganisms have been alive for thousands of years, barely moving except with shifts in earthquakes or eruptions. They're just active inside, with less energy than people thought possible to support life.
The team consists of 1, 200 scientists from 52 countries in disciplines ranging from geology and microbiology to chemistry and physics. A year before the conclusion of their study, they will present the findings before the American Geophysical Union's annual meeting opens this week, which they say are made possible by technical advances on drills and microscopes.
The scientists have been wondering about the point beyond which life cannot exist, but the deeper they dig, the more life they find. There is a temperature maximum—currently 122℃—but they believe this record will be broken if they keep exploring and developing more advanced instruments.
Questions remain, including how the microbes interact with chemical processes, and what this might reveal about how life and Earth coevolved.
