That’s covered under ‘natural’ solutions, also eligible for the prize. All you need to do is develop a plan to scale that economically to gigaton/year capacity and claim your prize! Should be easy, right? So just do it!
Nuclear power plants for desalination plants and the build out water pipelines and rail into the Sahara desert from the ocean.
Use irrigation canals covered in solar power panels for pumps etc.
Plant vegetation and build up forests slowly. Slowly expand across the desert and connect both ends the block off grids and repeat irrigation and planting until the desert is gone.
We can, and we certainly should, but that does not solve the problem because those trees will eventually die and that carbon will cycle back through the biosphere. Mankind extracted a ton of carbon from the ground, where it was locked away, and we put it back into the air. People are trying to find ways of putting all that extra carbon back somewhere where it won't affect the cycles in nature. Trees just temporarily lock up carbon.
If you cut down trees (sustainable forestry with selective, not clear cutting) and use the logs in durable housing construction, furniture making etc you are taking that carbon out of the loop for a hundred+ years if the housing/furniture is well looked after. Most housing could be built with timber. It might be temporary but buys us time, and trees are amazing CO2 capture machines that are cheap to scale up - they run for free on solar energy and look after themselves.
Stopping deforestation and massively boosting reforestation is one of the most effective things we can already do at scale. At this point we also need active carbon capture and significant reduction in emissions too, though - a multi-pronged approach.
Yes, but the point is that there is an upper limit to the contribution, and even reforesting unrealistically vast tracts of land does not make up for carbon extracted from deeper in the crust. Growing, cutting, and burying fast growing trees deep in the Earth, then replanting them, would not have that limit (although there would be other problems keeping the land fertile).
Well, most of the carbon in the ground that we're burning are long-buried trees, right? I wonder what it would take to just bury a lot of trees and let them regrow naturally.
My approach would be to find the best CO2/$ types of trees, buy them straight from the lumber industry, and sequester them in no-longer-used quarries. Just need to figure out a scalable way to ensure anaerobic conditions to help prevent CO2 release on breakdown.
At the time coal deposits formed the bacteria that broke down lingin and cellulose hadn't yet evolved, so just burying trees wouldn't work today as they would decay. You could probably burn the wood to produce charcoal (burning it in a low oxygen environment), and the bury that, but just cutting down a forest and burying it won't work.
I'm no chemist, but, wild guess, you might actually make things worse by favoring decomposition into methane instead of CO2.
I would think that a proper solution would require figuring out how to get all that carbon into a chemical form that is chemically stable and won't biodegrade. The ideal looks a whole lot like coal, I'd guess?
My understanding is that when wood first appeared on Earth nothing was able to decompose all of that cellulose for millions of years until microbes evolved a way to break the molecules apart and feed on them. I don't know if simply burying the trees is enough to sequester it away now that wood decomposes so readily.
Trees, unless you clearcut them (or they die off due to climate change) permanently lock up carbon. Yes, some die and decompose, but new ones grow up to take their place. It's just the total amount of biomass created that matters.
Long term the dead trees might release the carbon again to the atmosphere, but we are currently facing problems over the next decades. Even if trees would only move some amount of carbon "into the future", they could buy us precious time while we deploy other solutions for the problem. And of course, one can try to permanentely capture the carbon bound by trees by not letting them burn/rot after their life.
Dead trees lie on the ground, with all their sequestered carbon sitting there. It's not like the carbon is going back into the atmosphere, at least not without some process like combustion. Coal is basically dead trees. Before we started extracting coal and burning it, it was harmless to the atmosphere.
Doesn't rotting, or being eaten by microbes or termites that eventually get eaten or die and rot eventually lead to the release of the stored carbon?
AFAIK coal is composed mostly of trees that fell back before microbes evolved that could eat through their cellulose walls, and have had millennia of underground compression to further increase their stability - basically that process isn't available naturally to trees that fall today.
It takes roughly twice as long for a tree to decompose as it does to grow; and trees live a lot longer than that! So over time, the net sequestration should be positive.
no. Unless the tree vaporizes or burns, none of it gets back into the air. It is for all intents and purposes a permanent lock up. Mankind is the gatekeeper of whether to unlock this carbon prison in our choice to burn oil or wood.
Trees aren't the complete solution and the reason why has nothing to do with the tree dying and releasing the carbon.
What's going on here is that plants are converting CO2 into mass. A tree that isn't growing isn't creating new mass and therefore isn't lowering carbon in the atmosphere.
It's difficult to get enough total quantity, and it's also not rapid enough as it takes decades after planting (which would also take a lot of time) to soak up that extra carbon.
One aspect is that the required land area - https://climate.nasa.gov/news/2927/examining-the-viability-o... mentions 900 million hectares (2.2 billion acres), which would roughly cover the 10Gt/year asked by the x-prize - is enormous, and it's not an accident or negligence that this land isn't forested now, it's generally because we turned it into farmland or pastures.
Are we willing to take away 900 million hectares of land that produces food for the world and money for the locals away from that productive use and turn all of it into unproductive forest that won't get used for logging? Perhaps we are, but if there are other options for carbon removal that don't require as much land resources, that would be preferable.
Forests are basically carbon neutral once they're mature, peat bogs would probably be much more effective as carbon is continually sequestered underwater.
The problem is the space issue and that it takes a decade or two for there to be meaningful carbon uptake.
Most land is private so you can't go around planting willy nilly. What's worse is that you are technically not allowed to plant on most public land either, although for small amounts of native species, you can sneak by.
Ahem.. Not OP, but Canadian ex-treeplanter here, and I've planted 1.2M trees. I have many friends who've planted more, a couple probably up into the 10M+ range.
It seems insane that we aren't looking at trees more seriously. Here we have a self-reproducing, exponential, solar powered, organic, low-tech, carbon capture system. We don't even have to plant them, we can simply allocate land and let them do their thing on their own if we're patient for natural succession. Or we can accelerate the process by planting select species, thinning etc.
We should also be setting aside more of the remaining old-growth forests to protect them from being logged, as these forests represent a standing carbon sink (aside all of the other ecological benefits of protecting old-growth forest).
I know it's not the complete solution and that we need all the cards on the table, but I fear that in our appetite for high tech fixes, we're overlooking this simple biological solution.
Trees follow a slow-fast-slow pattern for capturing carbon.
Small new trees don't capture much.
Middle-aged trees capture a lot as they grow.
Old-growth trees don't capture as much as they reach the end of their life-cycle.
As others have said, trees are only temporary as they eventually die and need to be replanted. They're also slow to start, and need to be maintained (which costs carbon as well).
That's one country, for one year. The world has been burning coal for more than a century. To get back to preindustrial CO2 levels, all that coal needs to be unburned and buried again. That's the scale of the problem.