The carbon way below - We've only skimmed the surface

Where has all of Earth's carbon gone? A study says 90 percent is missing, and probably resides in the planet's deepest regions. We might be able to tap it. Uh-oh?
Written by Mark Halper, Contributor
Where has all the carbon gone? Look out below!

Now that we've found the Higgs Boson, we can turn our attention to tracking down a more tangible little rascal and figuring out its hidden mysteries: Carbon.

In a theory full of fossil fuels, diamonds, microbes and some tough tiny creatures called extremophiles, an international team led by the Carnegie Institution of Washington postulates that we've literally only scratched the surface of finding all of the planet's "C."

If true, it would be a walloping finding, considering that carbon is already the world's fourth most abundant element, and one that for all of its life-affirming properties (it is the essential ingredient in organic compounds) is most associated these days with the environmentally villainous carbon dioxide emissions of burning coal, oil and natural gas.

Scientists at Carnegie's Deep Carbon Observatory (DCO) believe that over 90 percent more carbon exists on Earth than is generally known. They say that meteorite studies show that the planet originated with three percent carbon by weight, or 30 times more than the currently measured 0.1 percent.

"So where did it all go?" asks Robert Hazen, DCO's executive director, and the co-editor of a new downloadable book (warning: big file) out today called Carbon in Earth.

Hazen and his colleagues have an answer: Most of Earth's carbon resides below Earth's surface. And when they say below, they mean it.

"Significant amounts may be locked into minerals and melts in the mantle and core," says Hazen.


For a quick review of your geology lessons: That plunges us down over 6,000 kilometers because each of those planetary wads has a radius of about 3,000 kilometers. Temperatures in the mantle and core can exceed 3,000 degrees C, at pressures 300 times of Earth's surface.

"It isn't a question of whether it exists," says Hazen, who I spoke with briefly last week as he and his colleagues were preparing for the DCO's three-day International Science Meeting that began yesterday in Washington, D.C., where they are revealing and discussing the book's findings. Whereas the Higgs hunt was a more existential exploration for a subatomic particle that no one had ever found, the carbon project is more of a giant behavioral examination of a common but also widely AWOL element.

"It's a question of where did it go?," notes Hazen. "How is it locked in? How does it cycle? What happens to Earth and how has Earth changed?" How does it contribute to the origin of life and changing life through Earth's history?"

Spot the oil gear. It's hard to miss the hydrocarbon hunter in the montage above from DCO's website. DCO is also looking for big clues on how to naturally store CO2.

Those are indeed big, interesting, probing, intellectual questions. And yes, SmartPlanet reader, it does indeed include a search for hydrocarbon fuel from those staggering depths.

After all, Shell Oil sits on the DCO's executive committee. And it's hard to miss the picture of the oil "pumpjack" - also known as a "nodding donkey" - on DCO's home web page.

According to Hazen, if there are hydrocarbon fuels down there, they won't be fossil fuels as we know them. Rather than originating from biological sources, as fossil fuels do, they would have formed from "abiotic" processes, like the pressurized heating of water and carbon, notes DCO's Rajdeep Dasgupta from Houston's Rice University.

Hazen says it would be unlikely to find oil, because temperatures would be too high. Natural gas - methane - would be more probable, he says.

"We expect that there is a source of natural gas that could come from the mantle, perhaps mixing with the other sources," he says. "One of the things we want to understand is exactly how much might there be. Methane could migrate up to the surface."

In a presentation in Paris last October, DCO's Christopher Ballentine from the U.K.'s University of Manchester said one of the goals was to "develop techniques to resolve the relative roles of biotic versus abiotic hydrocarbon production, with experimental investigation of abiotic methane synthesis under lower crust and upper mantle conditions."


The Carbon Observatory is not out to extract the stuff itself. They are doing the science. They are three years into a 10-year, $500 million study that is trying to ascertain the carbon contents. Their methodology includes examining magma and volcanic gases, and recreating the extreme temperature and pressure condition.

The team includes academics from 40 countries and many universities, such as Dasgupta's Rice and Ballentine's Manchester, the University of Washington and University College London. DCO is funded by the Alfred P. Sloan Foundation.

Up from the deep. DCO scientists are studying volcanic gases, such as above at the Mutnovsky crater in Kamchatka, Russia.

But you can bet that if Hazen's crew find natural gas, the likes of Shell and BP will figure out how to get it. If you find it, they will come. And extract. And burn. And release carbon dioxide.

Now, before you say, "woops, there goes the planet," take heart.

"What we're trying to do is understand the much more fundamental scientific basis for how that methane forms, how it moves within earth, how it interacts with rocks, and how that basic knowledge can be used to better understand and perhaps husband our planet," says Hazen.


Husband the planet?

Yes, says Hazen, the study could provide excellent tips on how to store carbon we burn on the surface, rather than release it to the atmosphere. If Earth has managed to keep 90 percent of its carbon underground, then the study could reveal clues as to how it keeps it there, and how regular Earthlings could do the same.

"If you understand something more about how carbon is being processed by our planet, it really becomes the key knowledge you need if you're going to sequester that carbon, if you're going to rebury it," says Hazen. "Earth is sequestering carbon in a very efficient process that's been going for billions of years."

Hazen points out that "extreme microbes" - small living organisms that survive in the deep and dark and that scientists also call "extremophiles" - are probably playing a role.

"We're also fascinated by deep microbial life," says Hazen. "Microbes that never see the light of day, that make their living by eating rock. Basically they look for chemical environments where they can eek out just a very slow life -'extremophiles,' which is the name for these kinds of microbes - are incredibly good at turning carbon dioxide into rock, into limestone. It's just how fossils' shells come about. It's how clams and mollusks make their shells."

Understanding the process could then help "potentially engineer microbes to speed up the process of burying CO2," he adds.

An in-depth knowledge of such extreme microbial action could then apply not only to carbon storage, but also to detoxifying all sorts of nasty waste, whether it's from factories, dumps, nuclear sites, or others, he points out.

The DCO also hopes to shed light on other aspects of Earth, such as the origins of life related to viruses and hydrogen, and the age of diamonds.

Who knows - they might even stumble across some potent antibiotics as they root through their extremophiles.

Images from Deep Carbon Observatory. (Middle image is a screen shot from its website).

Note: The original version of this story referred to the picture of the oil gear as a "derrick." It's actually a "pumpjack," also known as a "nodding donkey" and by other names. Thanks to reader Jeremy Boak for correcting, as you'll see in his comment below. Changed at around 8:15 a.m. PT, March 5.

Other deep dives on SmartPlanet (not all quite as deep):

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