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Photo: Kevin Krajick/Earth Institute.
Geologist Peter Kelemen surveys an outcrop of exposed mantle rock in Oman. “The light material is a carbon-based mineral that has reacted with the rock to form a solid deposit,” reports Columbia University.

Scientists from many specialties are working on new angles for dealing with global warming and carbon in the atmosphere. Today’s story features geologists.

Kevin Krajick reports at Columbia Climate School’s State of the Planet, “Geologist Peter Kelemen has been working in the desert of Oman for more than 15 years to study natural chemical reactions within rare deep-earth rocks that pull carbon from the air and lock it into solid mineral form.

“His goal: harnessing and speeding up those reactions to remove carbon on an industrial scale. Based in large part on his research, Omani entrepreneurs recently formed 44.01, a company working to scale up and commercialize the processes. The company was just awarded a $1.2 million Earthshot Prize. … We spoke with Kelemen about the science behind the project, its current state, and its prospects for the future.

Tell me about the rocks in Oman, and what makes them special.
“The mountains of northern Oman and along the coast of the United Arab Emirates host a huge block of oceanic crust and upper mantle that was thrust onto the edge of the Arabian continent. … It is 350 kilometers long, up to 50 kilometers wide, and many kilometers thick. It is tilted, and exposes rocks that formed more than 20 kilometers below the sea floor. Surface exposures of the Earth’s mantle are quite rare, and this is the largest in the world. …

“Rocks like this react rapidly with CO2 in the atmosphere and surface water, and this forms solid carbonate minerals, for example limestone. The process is spontaneous. So we’ve been seeking to understand how it works, and then design methods that accelerate it in order to store significant amounts of CO2 on a human time scale. We are focusing on injecting CO2 dissolved in water underground. It might use a lot of water, and of course water is very valuable in the Middle East, so we look for areas near the coast. …

How did 44.01 start, and what is your involvement?
“I and my colleague Jürg Matter, who was formerly at Columbia, were first approached by on Omani entrepreneur, Talal Hasan, in about 2017, when he was working for Oman’s sovereign wealth fund. Talal hoped to persuade the government to invest in CO2 storage in the mantle rocks. But then he ended up leaving the fund, and he and a childhood friend founded 44.01. Jürg now works with them about half time. I plan to remain in more of an advisory role.

Where would the carbon come from?
“44.01 has obtained a solar-powered device that removes CO2 directly from air, from the Swiss company Climeworks. They’re operating it near Oman’s capital city, Muscat. For pilot studies, we could also use CO2 captured from smokestack sources, like the many gas-fired power plants, water desalination plants and other industrial operations in Oman and the UAE. …

“We’ve obtained government permits and run some small pilot projects at a former scientific drilling site. We are now planning two much larger pilot projects, both expected to take place in 2023. Ideally we would achieve substantial results before the COP28 meeting in the UAE, in 2023. Eventually, we hope, some government or group of governments would pay them to lock up the carbon, at a rate of maybe $30 a ton. Globally, such costs end up being a few percent of GDP, comparable to the current costs of solid waste management.

“The main concern is that the rocks are not very porous. That leads to two difficulties. One, it can be difficult to get fluids to circulate rapidly through the rocks, and two, the pore space might eventually clog up with newly formed carbonate minerals. However, we are inspired by the fact that in some places the rocks have naturally become fully carbonated. That is, every magnesium and calcium atom in them has combined with CO2 to create solid minerals. So we know this can happen, and we have ideas about how it works. We have done theoretical calculations, and conducted experiments at the laboratory scale. But in the end, only field scale experiments will allow us to refine methods to do this at a reasonable cost.

Are there other places with similar rocks?
“Yes, but Oman and the UAE are the best. The next largest outcrops are in New Caledonia and Papua New Guinea. They would be great places to take CO2 from the air, but I think we need to demonstrate that this process works on the Arabian peninsula before trying to get things going on islands in the southwest Pacific. There are other, smaller areas that could work, including parts of California and Oregon. However, those spots are water-limited, and I expect local stakeholders would be concerned about that. …

“In addition to forming solid carbonate minerals, the reaction of surface waters with mantle rocks can form free hydrogen gas. It is widely viewed as a potential replacement for fossil fuels, specifically natural gas and oil, for transportation and home heating. And if derived at low cost from natural sources, it could also be used to generate electricity. We are continuing academic research on the rate of hydrogen formation, and studying ways that could be accelerated.”

More at Columbia Climate School’s State of the Planet, here.

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Photo: Guangxi speleology research team 702 via the Guardian.
Cave explorers have come across a sinkhole, or karst, in a semi-autonomous region of southern China. Previously known only to locals, it is 306 metres (335 yards) in length, 150 metres (164 yards) wide and 192 metres (210 yards) deep. It has a forest at the bottom.

When I was a kid spending summers on Fire Island, we all thought the Sunken Forest the most magical place ever. But just imagine if a forest were so removed from the world that it harbored previously unknown species! Scientists in China are beginning to study a forest of tantalizing possibilities at the bottom of a huge sinkhole.

Stephanie Pappas reports at Live Science, “A team of Chinese scientists has discovered a giant new sinkhole with a forest at its bottom. 

“The sinkhole is 630 feet (192 meters) deep, according to the Xinhua news agency, deep enough to just swallow St. Louis’ Gateway Arch. A team of speleologists and spelunkers rappelled into the sinkhole on Friday (May 6), discovering that there are three cave entrances in the chasm, as well as ancient trees 131 feet (40 m) tall, stretching their branches toward the sunlight that filters through the sinkhole entrance. 

” ‘This is cool news,’ said George Veni, the executive director of the National Cave and Karst Research Institute (NCKRI) in the U.S., and an international expert on caves. Veni was not involved in the exploration of the cave, but the organization that was, the Institute of Karst Geology of the China Geological Survey, is NCKRI’s sister institute. …

“Veni told Live Science, [that] southern China is home to karst topography, a landscape prone to dramatic sinkholes and otherworldly caves. Karst landscapes are formed primarily by the dissolution of bedrock, Veni said. Rainwater, which is slightly acidic, picks up carbon dioxide as it runs through the soil, becoming more acidic. It then trickles, rushes and flows through cracks in the bedrock, slowly widening them into tunnels and voids. Over time, if a cave chamber gets large enough, the ceiling can gradually collapse, opening up huge sinkholes. 

” ‘Because of local differences in geology, climate and other factors, the way karst appears at the surface can be dramatically different,’ he said. ‘So in China you have this incredibly visually spectacular karst with enormous sinkholes and giant cave entrances and so forth. In other parts of the world you walk out on the karst and you really don’t notice anything. Sinkholes might be quite subdued. … Cave entrances might be very small, so you have to squeeze your way into them.’ 

“In fact, 25% of the United States is karst or pseudokarst, which features caves carved by factors other than dissolution, such as volcanics or wind, Veni said. About 20% of the world’s landmass is made of one of these two cave-rich landscapes. 

“The new discovery took place in the Guangxi Zhuang Autonomous Region, near Ping’e village in the county of Leye, according to Xinhua. Guangxi is known for its fabulous karst formations, which range from sinkholes to rock pillars to natural bridges and have earned the region UNESCO world heritage site designation.

“The sinkhole’s interior is 1,004 feet (306 m) long and 492 feet (150 m) wide, Zhang Yuanhai, a senior engineer with the Institute of Karst Geology, told Xinhua. … Chen Lixin, who led the cave expedition team, told Xinhua that the dense undergrowth on the sinkhole floor was as high as a person’s shoulders. Karst caves and sinkholes can provide an oasis for life, Veni said.

‘I wouldn’t be surprised to know that there are species found in these caves that have never been reported or described by science until now,’ [team leader] Lixin said.

“In one West Texas cave, Veni said, tropical ferns grow abundantly; the spores of the ferns were apparently carried to the sheltered spot by bats that migrate to South and Central America.

“Not only do sinkholes and caves offer refuge for life, they are also a conduit to aquifers, or deep stores of underground water. Karst aquifers provide the sole or primary water source for 700 million people worldwide, Veni said. But they’re easily accessed and drained — or polluted.” More at Live Science, here. No firewall.

The Washington Post offers more on the forest. Reporter Marisa Iati writes, “Large sinkholes are known in Chinese as ‘tiankeng,’ or ‘heavenly pits.’

“The sinkhole near Ping’e village is known to local residents as Shenying Tiankeng, or ‘the bottomless pit.’ From a distance, the cliff looks like a pair of soaring wings, the Guangxi Daily newspaper reported.

“The researchers arrived at the sinkhole May 6 and saw dense trees blocking the bottom of the pit, the newspaper reported. They used drones to explore the area and then rappelled and hiked to the bottom for several hours, passing dense thorns and fig plants. They found three caves in the wall that may have formed early in the sinkhole’s evolution, Zhang Yuanhai, senior engineer at the Institute of Karst Geology of China Geological Survey, told Chinese state-run news agency Xinhua.

“While trees exist in other sinkholes, Veni said they can only grow if the hole is shallow enough and has a big enough opening to let in sunlight. The newly explored sinkhole is almost definitely home to small animals, such as insects, that are currently unknown to scientists, he said.”

More at the Post, here.

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Photo: Matthew Genge, Imperial College London.
The simulation of the Scottish countryside for an online geology class included buildings, walls, and gravestones.

Although it always seemed likely I would turn out to be an English major, I did have to choose a science in college. My mother thought it was charming that the geology class had the same two professors from the time she was there. She recommended the course. And a few people said geology would be easier than the other sciences. Ha! They were wrong about that! But I learned as much as I could, if not very well, and to this day I can tell you if your dorm is made of Wissahickon Schist.

If I thought geology was hard back then, what would it have been like this past year? At Atlas Obscura, Robin George Andrews reports on the challenges of teaching it online during the pandemic.

“If you decide to pursue a degree in geology,” Andrews notes, “be prepared to spend some time in the wilderness, where you will be asked to find and analyze rocks that will help teach you how the planet works. You will sketch curious outcrops, smash stone to pieces, peer at crystals through a hand lens, and, every now and then, even lick rocks, if it comes to that, all under the watchful, judging eye of your instructors.

“When the pandemic kicked into gear back in March 2020, these both scintillating and stressful field schools were no more. Geology instructors across the world were at a bit of a loss as to what to do. Many understandably concluded that there was no way to replicate this hands-on learning experience and just made do, but Matthew Genge, a planetary scientist at Imperial College London (ICL), had an epiphany.

“By happenstance, he had taken up the hobby of video game design a decade earlier. ‘It’s pure problem solving,’ he says. ‘You get that achievement buzz when you make something work or overcome some challenge.’

“One of his colleagues, fellow ICL geoscientist Mark Sutton, had also been dabbling in the same digital sandbox. So they decided to put their skills to pedagogical use:

They built video game versions of the field trips their undergraduate students would normally go on, where they could practice the same techniques and learn about the planet in the same way they would in the real world.

“It started with a 3D replica of Sardinia (and Mt. Etna on Sicily), where students galivanted about, looking for ancient fossils, prodding volcanic rocks, and exploring an abandoned silver mine. But like in all good video games, things escalated quickly. Before long, students were piloting spaceships, fending off hostile fighters, and trying to find a good place to land on an asteroid (to study its chemistry). …

“Back in 2019, Sutton had brought a drone to Sardinia — one of the usual field trip locations — and took a bunch of photographs of the places they were visiting to learn geology. A year later, Genge used those photographs, along with some bespoke computer code, to whip up a virtual version of the study area.

“In the (real) field, the objective would be to examine a location, study it scientifically, pose a research question, and then attempt to answer it. The same scenario played out in the virtual world Genge and Sutton created.

“For example, an area that was once a lake, 330 million years ago, is now jam-packed with plant and animal fossils. There are even ancient traces of rain, which made little indentations that have been naturally preserved. Some of these impressions are elongated in one direction, which can be used to estimate wind speed. A student might find these rain prints, examine them in high resolution, and then write something about how they might be used to understand what Earth’s atmosphere was like back then.

“The students were engaged, and the quality of their work was similar to what the instructors had seen in previous field seasons. ‘Two of the projects were close to being publishable,’ says Genge.”

More details (including how the video game meant the study of meteorites could become a space adventure) at Atlas Obscura, here.

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