In different locations worldwide, scientists are digging holes below the surface of the earth. Since 2009 they have been probing the deepest parts of our planet, building a picture of the ecosystem that thrives in such unlikely surroundings. And in December 2018 they revealed some of their incredible discoveries.
From the strange creatures that dwell in the depths of the world’s oceans to the countless insects and spiders that inhabit earth, our planet plays host to a dizzying array of life. In fact, a study published in the journal PLOS Biology estimates that almost nine million species currently exist here.
Amazingly, however, most experts believe that we have barely scratched the surface in terms of life on earth. And according to the same study, some 86 percent of all animals and plants that live on land remain to be discovered – along with a staggering 91 percent of those in the seas.
With this in mind, it’s clear that our world is teeming with undiscovered life. In fact, scientists identify up to 18,000 new species every year. And while some of these will be microscopic organisms invisible to the naked eye, others are more substantial and have gone undetected by humans for centuries.
From the grasslands that occupy the savannas and prairies of Africa and North America to the vast marine habitats that make up the planet’s oceans, many different ecosystems thrive on earth. And unsurprisingly, it is in these complex, connected environments that many of the world’s newest species are found.
However, ecosystems such as these are not the only place where new life is being discovered. And thanks to a group of scientists from around the world, we are learning more about a completely different biosphere. Indeed, it exists thousands of feet beneath our feet.
Below the surface of our planet sits the lithosphere – a firm outer shell that comprises Earth’s crust, as well as the upper mantle. And beneath that is the asthenosphere, a sticky layer where temperatures can reach a staggering 2,336 degrees Fahrenheit.
According to experts, some 90 percent of all the carbon on our planet is located inside earth. Yet scientists are only now learning just how deep carbon impacts life on the surface, the atmosphere and the oceans.
In 2007 Robert Hazen, a senior staff scientist from the Carnegie Institution’s Geophysical Laboratory in Washington, D.C., gave a talk at New York City’s Century Club. In it, he discussed the role of geophysics in kickstarting life on earth. And apparently, his ideas impressed Alfred P. Sloane Association program director Jesse Ausubel, who was in the audience at the time.
Fortunately, the Alfred P. Sloane Association hands out grants to research projects. And with its help, Hazen and his colleagues established the Deep Carbon Observatory (DCO) in 2009. Based at the Carnegie Institution, the project sought to discover how deep carbon cycles affect our planet as a whole.
Today, the DCO Science Network consists of more than 1,000 scientists from around the world. At around 100 different locations worldwide, representatives from over 50 countries work to further mankind’s understanding of deep carbon. And with the ten-year project finishing in 2019, some amazing results have been emerging.
At the DCO, research is split into four communities: Extreme Physics and Chemistry, Deep Life, Deep Energy and Reservoirs and Fluxes. Using a variety of techniques, each group works to build up a better understanding of how deep carbon impacts life on this planet. Meanwhile, the central Data Science Team collects information from across the project and converts it into vital datasets.
So far, the project has revealed some fascinating finds. For example, in the Reservoirs and Fluxes department, scientists are exploring how much of earth’s carbon originates from its interior. Meanwhile, the Extreme Physics and Chemistry community is working towards getting a better understanding of how the element reacts to extreme conditions.
Meanwhile, the Deep Life community are making some staggering discoveries. Apparently, these scientists study life beneath the surface of earth, exploring how this complex biosphere interacts with our planet’s deep carbon cycle.
When the DCO first launched, scientists involved in the Deep Life project began their search cautiously. “Ten years ago, we had only sampled a few sites – the kinds of places we’d expect to find life,” associate professor Karen Lloyd at the University of Tennessee at Knoxville told Phys.org in 2018.
However, over the years the DCO’s search has expanded to cover hundreds of sites under a number of continents and seas worldwide. In some locations, researchers drilled more than a mile and a half deep beneath the ocean floor. They also sampled microbes from boreholes and mines more than three miles deep.
At these depths, high temperatures, intense pressure and a lack of nutrients and light all contribute to unfavorable conditions for life to exist. However, what researchers have discovered has shocked the scientific community – and changed what we know about life on earth for good.
On December 10, 2018, the annual meeting of the American Geophysical Union began in Washington, DC. And to mark the occasion, the DCO announced some of its discoveries over the past nine years. Apparently, the deep subsurface of our planet is far more welcoming than we might have believed.
Amazingly, scientists have found a vast biosphere beneath the earth’s surface that is twice the size of the world’s oceans. In fact, they believe that it could extend to over half a billion cubic miles. Moreover, the ecosystem is thought to weigh as much as 23 billion tons. For reference, that’s almost 400 times heavier than all of the humans on earth put together.
Apparently, this underground biosphere is so populous that scientists have referred to it as a “subterranean Galapagos.” And just like the famously diverse islands in the Pacific Ocean, this unlikely habitat has spawned a staggering array of life. In fact, researchers have discovered that all three biological domains are present in the subsurface of the earth.
According to the three-domain system of classification, all known life can be split into three categories: bacteria, archaea and eukaryote. And amazingly, research from the DCO suggests that a staggering 70 percent of the planet’s bacteria and archaea live beneath the surface of the earth.
“It’s like finding a whole new reservoir of life on earth,” Lloyd told the Guardian in 2018. “We are discovering new types of life all the time. So much of life is within the earth rather than on top of it.” In fact, it is believed that millions of different organisms exist there, mostly still undiscovered and uncategorized.
Regardless, some particularly fascinating organisms have already emerged. For example, researchers were able to take a closer look at Altiarchaeales, a barbed type of archaea that thrives in sulphuric springs, and Geogemma barossii, a single-celled microbe that lives in temperatures of 250 degrees Fahrenheit.
At one site, researchers retrieved an organism from a depth of 1.5 miles. Apparently, it existed buried underground for millions of years – where it may have developed a method of energy production completely independent of the sun. Instead, experts suspect that it produces methane, using the gas to restore itself rather than reproduce.
In fact, experts were stunned to discover that any life was present under such limiting conditions. “The strangest thing for me is that some organisms can exist for millennia,” Lloyd told the Guardian. “They are metabolically active but in stasis, with less energy than we thought possible of supporting life.”
According to experts, much of the life discovered by the DCO exists on a completely different timescale than that which occupies the surface of the earth. And amazingly, some of them consume nothing but energy drawn from the surrounding rocks. Furthermore, they might only move in circumstances where the earth itself shifts, such as volcanic eruptions and earthquakes.
“We humans orientate towards relatively rapid processes – diurnal cycles based on the sun, or lunar cycles based on the moon – but these organisms are part of a slow, persistent cycle on geological timescales,” Oregon State University microbial ecologist Rick Colwell explained to the Guardian.
Apparently, various scientific innovations have allowed scientists to dig deeper in search of life than ever before. And while new drilling techniques have allowed them to penetrate further into the earth’s crust, advances in microscopic technology have enabled them to observe life at ever smaller levels.
Amazingly, research has yet to reveal the limitations of life in earth – at least as far as factors such as pressure, temperature and energy are concerned. Indeed, there are microbes that are able to survive in temperatures up to 250 degrees Fahrenheit. For reference, that is 90 degrees hotter than the temperature of a well-cooked steak.
Currently, the record for the deepest lifeform is held by an organism that was discovered over three miles down. Meanwhile, in marine waters, the record is more than 6.5 miles below sea level. Organisms at these depths are subjected to intense pressure at least 400 times greater than that on the surface.
Scientists believe they will discover organisms that can live in temperatures higher than the current record 250 degrees Fahrenheit. “Exploring the deep subsurface is akin to exploring the Amazon rainforest,” senior scientist Mitch Sogin of the Marine Biological Laboratory Woods Hole told Phys.org.
“There is life everywhere,” Sogin continued, “and everywhere there’s an awe-inspiring abundance of unexpected and unusual organisms.” He also touched on an ingredient which doesn’t emit energy or light known as “dark matter,” and suggested that there may be far more to it than scientists have previously believed.
“Molecular studies raise the likelihood that microbial dark matter is much more diverse than what we currently know it to be, and the deepest branching lineages challenge the three-domain concept introduced by Carl Woese in 1977,” Sogin explained. “Perhaps we are approaching a nexus where the earliest possible branching patterns might be accessible through deep life investigation.”
Interestingly, associate professor Karen Lloyd at the University of Tennessee at Knoxville believes that they may find life forms existing in temperatures exceeding current temperature records. “There’s no one I know who thinks that’s the theoretical limit,” she told the BBC in 2018. “For example, we know some of the problems associated with high temperatures, such as the disordering of liquids and membranes, are at least partially compensated by higher pressures.”
And if we do discover organisms living at even greater temperatures, this could have far-reaching implications. In fact, if lifeforms can thrive in such extreme conditions on earth, it’s possible that other planets in our solar system might be harboring similar secrets below the surface.
“I think it’s probably reasonable to assume that the subsurface of other planets and their moons are habitable, especially since we’ve seen here on earth that organisms can function far away from sunlight using the energy provided directly from the rocks deep underground,” Colwell told the BBC.
Meanwhile, back on the earth’s surface, the DCO’s research has raised a number of fascinating questions. For example, scientists have queried why life in the subsurface is so similar on different continents, such as South Africa and Seattle in Washington – two places located some 10,000 miles apart.
Moreover, researchers have questioned what exactly deep carbon can tell us about the evolution of life. Specifically, they wonder whether organisms emerge in the molten depths of the earth and migrate outwards, or if they start out on the surface and travel down through the planet’s crust.
Today, research at the DCO continues, with scientists drilling ever deeper in search of life. And with techniques and equipment constantly improving, it seems likely that records will continue to be broken. But with so many strange organisms already discovered, what other secrets might be lying in wait?
“Our studies of deep biosphere microbes have produced much new knowledge, but also a realization and far greater appreciation of how much we have yet to learn about subsurface life,” Colwell told Phys.org. “For now, we can only marvel at the nature of the metabolisms that allow life to survive under the extremely impoverished and forbidding conditions for life in deep earth.”