Environment

Scientists Reveal a Massive Biosphere of Life Hidden Under Earth's Surface

Earth is not the home you think it is. Far below the scant surface spaces we inhabit, the planet is teeming with an incredibly vast and deep 'dark biosphere' of subterranean lifeforms that scientists are only just beginning to comprehend.

Hidden throughout this subsurface realm, some of the world's deepest and oldest organisms thrive in places where life shouldn't even exist, and in new research, scientists have quantified this 'dark matter' of the microbial world like never before.

In a preview of results from an epic 10-year collaboration by over 1,000 scientists, Lloyd and fellow researchers with the Deep Carbon Observatory (DCO) estimate the deep biosphere – the zone of life under Earth's surface – occupies a volume of between 2 to 2.3 billion cubic kilometres (0.48 to 0.55 billion cubic miles).

That's almost twice the volume of all the world's oceans – another enormous natural environment that lies largely unexplored by humans.

And just like the oceans, the deep biosphere is an abundant source of countless lifeforms – a population totalling some 15 to 23 billion tonnes of carbon mass (between 245 to 385 times greater than the equivalent mass of all humans on the surface).

The findings, representing numerous studies conducted at hundreds of sites around the world, are based on analyses of microbes extracted from sediment samples sourced 2.5 kilometres (1.6 miles) under the seafloor, and drilled from surface mines and boreholes more than 5 kilometres (3.1 miles) deep.