When I visit classrooms to talk about where our energy comes from, I like to bring along a decent-sized chunk of wood from my woodpile. It’s a prop I use to make a specific point about something students may have learned conceptually but might not yet grasp fully. I want them to understand that atmospheric carbon dioxide isn’t just an invisible, weightless gas — it has real, tangible weight.
I explain how most of our energy sources, whether wind, hydropower or fossil fuels, all trace back to solar energy stored over vastly different time scales — from minutes and hours to millions of years. Then, holding up the heavy log, I ask: Where do the molecules that make up this wood come from?
Students often know about photosynthesis, but they’re still often stumped by the question. Someone nearly always guesses it comes from the soil. But if that were true, we’d see sinkholes or empty spaces under trees as they grew — and we don’t.
It’s usually when I give them a clue that things start to click. I ask, What happens when I burn this log in my wood stove? Where does the mass of the wood go? That’s when the lightbulb moment happens: Of course! The carbon in the wood came from the atmosphere, where the trees absorbed it, using solar energy to build their structure. When we burn that log, poof — most of that carbon goes right back into the atmosphere.
Carbon the shapeshifter
It’s no surprise that kids don’t immediately connect the dots — it’s not intuitive. The vast amount of woody biomass around us — our birch and spruce forests — is literally manufactured from thin air. Even after learning about it in school, it’s hard to grasp that all this solid mass comes from something as invisible and seemingly weightless as carbon dioxide.
It’s equally hard to understand how something so seemingly innocuous is responsible for affecting the Earth’s climate so dramatically. Yet science overwhelmingly tells us it does. Carbon dioxide, or CO₂, is a major part of Earth’s thermostat—it’s our planet’s blanket that keeps us warm. And just like the quilt on our bed, how thick that blanket is matters a lot. The amount of carbon in our atmosphere is closely linked to Earth’s climate and has been for billions of years.
The total amount of carbon on Earth has remained essentially constant since the planet formed. However, where carbon is located and the form it takes can vary widely. There are four main “reservoirs” where carbon is stored, including the atmosphere, the oceans, the biosphere (all living things, including you, me, and that log from my woodpile). But the vast majority of carbon on Earth, like, well over 99%, is found in the rocks under our feet.
Rock Weathering and the Slow Carbon Cycle
The exchange of carbon between rocks and atmospheric carbon is ongoing, but it usually happens over much longer timescales than the growth of trees in our backyard. Those trees are part of the fast carbon cycle; rocks, on the other hand, belong to the slow carbon cycle. Carbon can be locked into rocks when living things die and are buried, taking their carbon with them. That can include tiny crustaceans, whose shells over time form rocks like limestone that have very high carbon content. Or, it can include everything we call fossil fuels — ranging from long-dead trees that have been buried and cooked into coal, or marine microorganisms that were converted to oil and gas.
Rocks also interact directly with the atmosphere, absorbing and releasing carbon over time through processes like weathering. If you break open a rock, you’ll notice that the inside often looks different— darker, smoother or shinier. That’s because the outer surface has undergone chemical reactions with the air. If the rock has a lot of iron in it, the rocks might react with oxygen, literally rusting and turning reddish. But rocks also interact with CO2 to form carbonates. Rain, which picks up CO₂ as it falls through the atmosphere and becomes weakly acidic, interacts with rocks, binding up carbon molecules with the exposed rock matrix in a process called chemical weathering. The outside of the rock forms a weathered “rind,” like the peel of an orange.
This chemical weathering of rocks is a slow process, which is why scientists call it the slow carbon cycle. Over time, the freshly exposed surface will weather to look just like the outside, but it won’t happen quickly. But on geological timescales, carbon is continually cycled between rocks and the atmosphere, usually in a pretty balanced way. When that balance gets out of whack for some reason, so does the Earth’s climate. Carbon isn’t the only factor controlling climate, but it’s one of the most influential.
For example, the Himalayas, one of Earth’s youngest mountain ranges, haven’t been worn down much yet. Some geologists believe that when the Indian subcontinent collided with Asia 55 million years ago, it pushed up a massive amount of fresh, carbon-poor oceanic crust like a giant planetary sized bulldozer, exposing it to the elements. This exposed crust weathered, absorbing CO₂ from the atmosphere and tipping the global balance, kicking off a period of ice ages that technically we are still in today.
Taking out the trash
As a thought experiment, imagine if carbon didn’t just vanish when we burned fossil fuels. What if we had to physically dispose of the CO₂, like taking out the trash? For every cord of wood I burn, I produce about a ton of CO₂. That’s far more than the ashes I scoop out of my wood stove each week. Or, imagine that for every gallon of gasoline I burn, I’m left with 20 pounds of waste—because that’s how much CO₂ each gallon produces. If this was solid waste, after a typical fill-up, I’d be dealing with 400 pounds of waste. If every Fairbanks resident had to manage that amount, and we included CO₂ produced through local power generation and heating, it would create a massive waste problem. If we piled it all up, it would result in a hill about a square mile in size and six feet tall. Every year. That’s a lot of waste.
But we don’t have to take out that trash, or even think about it that much. Those tons of CO₂ we produce each year just float away. That makes it easy to ignore. Yet there’s growing evidence that we can’t afford to ignore it. Ideally, we’d dramatically reduce the amount of CO₂ we release into the atmosphere. However, there is increasing consensus among scientists that reducing emissions alone won’t be enough to meet climate goals.
That’s why the idea of a “second approach” to tackle climate change is gaining traction. In addition to transitioning to renewables, we may need to capture CO₂ directly from sources like power plants or industrial sites — or even from the air — and store it permanently underground. This approach could become a vital companion strategy in our efforts to combat climate change.
Alaska has some of the best carbon storage potential in the world
Alaska has an abundance of oil and natural gas, largely thanks to its unique geology. Two key ingredients are needed to create oil and gas reserves. First, you need organic material buried deep underground and “cooked” over time. Second, you need a way to trap the hydrocarbons formed in that process. Without a trap, hydrocarbons would either be too diffuse to harvest or would gradually escape to the surface.
Typically, hydrocarbons migrate through the subsurface until they encounter an impermeable seal — like a layer of clay — that traps them in tightly sealed natural “containers” for millions of years. Once emptied, these natural containers could potentially be repurposed to store carbon. If done properly, there’s no reason to think the carbon couldn’t remain stored for millions of years, just like the original oil and gas.
To store carbon underground, we would want to use well-characterized containers, or reservoirs. These reservoirs can be found thousands of feet below the surface in layers of sand, coals, and even salt. Depleted oil and gas fields are prime candidates for carbon storage because data exists from years of production that allow us to understand the size, seals, and faults that have held materials in that container over geologic time.
In Alaska, the Cook Inlet region is receiving attention as an excellent potential carbon storage location. Preliminary estimates of its depleted oil and gas fields and unmineable coal seams indicate it may have some of the greatest storage capacity on the West Coast of North America. Its prime location at tidewater offers access not only for local storage but also for markets in Asia seeking locations on the Pacific Rim to sequester their carbon emissions as part of their decarbonization goals.
Storing carbon underground is already being done in other places. About a year ago, I joined a group of Alaskans to visit North Dakota, which is one state that is leaning into this opportunity in a big way. We were able to tour an ethanol plant that is sequestering CO₂ to get pretty close to a zero-waste operation. And just to the north, adjacent to the Boundary Dam coal plant in Saskatchewan, is the largest carbon capture and storage facility currently operating in North America.
The other place that has been a leader is Australia, and Santos, who operates the Moomba carbon storage facility in Cooper Basin, is working to bring some of their technologies and strategies to Alaska. Along with partners such as Arctic Slope Regional Corporation Energy Services, they recently won two grants from the Department of Energy. One for $3 million to perform feasibility analysis of direct air capture technology in three regions of Alaska, and another for $50 million to further characterize the storage suitability of a location on the North Slope. This is in keeping with ASRC’s goal of operating their Pikka field as a near-zero carbon operation.
Turning atmospheric carbon into stone
But Alaska is big, with a complex and varied geology. We have all kinds of rocks, which means more options for carbon storage than just using spent oil and gas fields.
There are also ways to accelerate natural processes like chemical weathering of rocks, which normally take place over geologic timescales. For example, in Iceland, they’re capturing CO₂, mixing it with warm geothermal water (mimicking acidic rain but supercharged), and injecting it underground — like fizzy seltzer water — where it reacts with fresh volcanic rock. This process turns CO₂ into stone in just years, rather than centuries.
In Greenland, they’re experimenting with using glacial silt — often called “glacial flour” — which hasn’t been exposed to the atmosphere and is therefore unweathered. They’re shipping it to Denmark to spread on farm fields, where it serves two purposes: It absorbs CO₂ quickly and provides minerals that naturally boost crops. Because this fine material has a high surface area, it reacts faster than larger rocks.
And guess what? We also have a wealth of volcanic rocks and plenty of glacial silt. This combination of resources makes Alaska uniquely positioned to explore innovative carbon storage and capture methods.
Could Alaska be the next leader in carbon capture and storage?
Recent polling indicates that over half of Alaskans are unfamiliar with carbon capture and storage — also called CCS for short. Even fewer are aware that Alaska’s unique geological features, such as depleted oil and gas fields in Cook Inlet and the “right” rocks, position it as a prime candidate for CCS initiatives. These resources could facilitate the development of a new industry focused on carbon warehousing, direct air capture plants, and innovative strategies like those Iceland and Greenland are experimenting with.
By leveraging its natural assets, Alaska could become a leader in carbon management, attracting investments and creating jobs in this emerging sector. As uncertainty around oil and gas production in Alaska grows, could carbon management be a key new industry for diversifying and bolstering Alaska’s economy in the future?
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