[#9] Geo-Engineering II - Nature's Way

Asking Nature to Atone for our Climate Sins

There’s a better way to remove atmospheric carbon. If DAC is brute force, akin to karate or boxing, nature-based solutions are subtle, more like Tai Chi or jiu jitsu. Nature itself is a massive solar-powered carbon-sucking system, tweaked for efficiency over billions of years. Leveraging those carbon flows is a far more efficient way to atone for our carbon sins than DAC.

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The earth breathes. As the biosystem inhales – forests and fields, oceans and plankton - carbon dioxide breaks into the carbon that’s the backbone of all biomass. As it exhales – leaves fall, trees rot and cellular life dies – that same carbon re-combines with oxygen and returns to the atmosphere. In and out. Each day, every year. As you might imagine (given the size of the planet) gargantuan amounts of carbon move through this cycle. Compared with our annual emissions, these earthly lungs are like a beachball next to tennis balls. The earth breathes a volume of carbon dioxide more than ten times[1] current emissions.

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That relative difference is the basis of an intuitively elegant geo-engineering solution. If we can tweak those giant lungs – trigger forests, fields or oceans to retain a few percent of its carbon – we’d alter the carbon cycle on a scale relevant to the problem. Slight interference in carbon flows at the scale of a beachball might result in changes the size of a tennis ball. The National Academy of Sciences estimates that we need to remove about 10 GT of CO2 annually by 2050. That’s just 3% of the natural cycle.

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Sounds easy. Reality is more complex. Scale - not much of that biomass is easily available. Permanence - the grabbed carbon must be stored effectively forever. Speed - this needs to happen within decades. And, of course, Bad Warming will put enormous stresses on natural carbon cycles. To be clear: this is no substitute for reducing emissions – it’s a Hail Mary insurance play to lower atmospheric carbon after we’ve reduced our emissions to zero.

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In theory, we could plant tens of billions of trees and be done with it. Groups like OneTreePlanted solicit donations to plant trees all over the world. Bands like Coldplay regularly claim to have planted enough to offset their rock tours. It sounds right - the wood pulls carbon out of thin air into solid form. But we don’t have enough land to grow trees in sufficient quantity since we use most of it for farming[2] . Permanence is also an issue since those trees can burn, or die – especially under Bad Warming. But it’s a start.

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Tropical rain forests hold massive amounts of carbon. Today we tear them down for cow pastures. It’s nuts. Restoring just a fifth of what we’ve destroyed would offset most historical emissions[3] . That’s not a technical problem, but a financial and political one. Money would solve it. Pay Brazil, Indonesia, Congo and Angola and other countries to restore tropical forests before they’re gone for good. That sounds a lot cheaper than the tens of trillions DAC would take. This feels so obvious, it’s hard to believe we haven’t done it yet. Countries don’t chop down forests because they want to. They do it because poor people need to make a living, or cattle farmers are greedy. Both can be paid off.

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Soils are a huge carbon reserve, about twice that of the atmosphere, mostly roots and charcoal. Much of the carbon held by croplands has been lost over the past few centuries by ploughing. Restoring that carbon could reverse historical emissions. Incentives to change farming behaviour are key. Start with no-till farming, so plant crops into pasture grasses. What happens above ground, dictates what happens below. Roots grow as deep as the plant is tall. Change grazing practices from heavy intensity to moderate to increase root growth. Plant switch grass across vast swaths of marginal land, and cut or burn it each fall, so the roots constantly push more carbon into the earth.

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Biochar is my favourite intervention in natural carbon flows. Intercept a small amount of annual biomass production – crop residue, forestry waste, or just fallen trees that would rot on forest floors – chop it up and expose the residue to high temperatures with no oxygen (pyrolysis). This transforms biomass, which rots, to mineralized carbon, which doesn’t. Done right, that carbon is stable for decades or centuries. Biochar has value. Put in agricultural fields to enhance soil health and water retention. But we could just make giant piles – carbon mined from the sky. Unlike DAC, biochar doesn’t need external energy. Imagine massive distributed systems of biochar production: large stationary industrial sites where biomass is produced or grown to purpose; smaller mobile units move across the countryside to covert seasonal biomass; robots[4] roam fields post-harvest to convert crop residue on the spot.

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We could burn biomass for energy and capture the exhaust carbon - traditional CCS with a biomass twist (BECCS). But BECCS comes with the complexity of CCS. Seems silly to let nature concentrate the carbon then re-capture it after it’s dilute again. Plus, electricity is a low-value output.

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There’s a better way to use biomass and capture its carbon. Woodland Biofuels (an ArcTern portfolio company) profitably converts waste biomass into hydrogen, renewable natural gas (rNG), methanol (shipping fuel) or ethanol. A happy side-product is a pure stream of CO2 – no need to ‘re-capture’ it in the stack. Hence, the incremental cost of storing the carbon is near-zero. Nature captures, we use and store. Their plants are massively carbon-negative[5] chemical factories. Seven Woodland hydrogen plants (of the hundreds existing biomass waste could support) capture what the entire global DAC industry has planned today. Profitably.

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The downside to the natural carbon cycle is it cuts both ways. Bad Warming will stress natural systems. These massive carbon flows may turn against us. If that happens, it’s all over. Just like a tropical forest sucks a lot of carbon, it gives up a lot if it dies. As the Amazon gets cut, it may de-stabilize[6] and pass a point of no return to die off. That’s a massive carbon bomb, equivalent to more than century of human emissions. Canada’s forests have long been a carbon sink (to the tune of ~60 MT, or 10% of our national emissions) but in the past couple of decades have turned from sink to source as fires, drought and disease take hold. They now give off as much ghg’s as we’ve reduced from industry. We simply cannot let natural systems degenerate any further.

Biogeotherapy - renewed, re-invigorated natural systems as therapy for our planet. Life as? geological healing force. Biogeotherapy doesn’t just atone for our climate sins, but keeps functional the ecosystem services we rely on: rain, nutrient cycling, erosion control, water regulation, pollination, forest health, oceanic food chains. Once broken, they’re effectively unfixable. These services fall outside economic frameworks. Want to put a price on it? These services have an economic value of around $50 trillion[i] annually (twice global GDP).

Re-connecting with nature ain’t a hippie thing. It’s a survival thing.

[1] We emit 37 GT of CO2 annually. About half is taken up by plants and oceans now, so net emissions are ~20 GT/yr. Total biomass production – oceans, soils, plants - is ~150 GT (half is carbon, which decomposes to ~275 GT of CO2).

[2] If we all became vegetarian pressure on land use would be alleviated since most industrial grain goes to animal crops – a highly inefficient way of producing protein.

[3] See Flannery, T., Here on Earth, 2010, pg. 260 “If we could reverse this dismal trend, and by 2050 restore between 8 and 17 per cent of what we have destroyed, then between forty billion and two hundred billion tonnes of CO2 could be sequestered in the growing rainforest. Given that we’ve put around two hundred billion tonnes of CO2 into the atmosphere over the past two hundred years, that reversal could theoretically get close to balancing Gaia’s carbon books.”

[4] Startup Climate Robotics’ field robots take in crop residue, and pass it through heated augers to poop out biochar in-situ. Move the factory to the biomass, not the biomass to the factory.

[5] For example, sixteen tonnes of CO2 is stored for each tonne of hydrogen produced. Compared to green hydrogen, which is (theoretically) zero-carbon, this is deeply carbon-negative.

[6] That giant tropical forest makes its own rain: after rain initially falls on the west coast, it re-evaporates into new clouds, moving eastward, and the cycle repeats. Unless it has a certain scale, that cycle can’t get going, and the eastern parts face drought.

[i] See The value of the world’s ecosystem services and natural capital, Nature, Vol 387, May 15, 1997 and Changes in the global value of ecosystem services, Global Environmental Change, Vol 26, May 2014, pg 152-158

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