[Kydlaw]

> I have no doubt that if humanity wanted to, it could sequester all the carbon necessary to reverse climate change

While this solution is appealing, it always leads to more questions than answers. Let's assume the How is solved. Where do you store it? Can it scale and if yes with which scenario? - Infinite growth? No way, it's physically impossible. - With a reduction? Maybe, but what will be the cost then? Will it be cost effective?

I think at that point we are back at the OP question.

[qchris]

If only there were existing storage mechanisms that existed in remote areas like forests or swamps. We could probably protect those areas, maybe even put new storage devices in. Ideally, of course, they'd run off a renewable source of energy like solar and be self-cooling. Of course, we wouldn't want the upfront cost to be prohibitive, so something self-replicating would be great. And to diagnose the health of these systems, maybe something humans have had centuries of experience managing? It'd be even cooler if we could locate a bunch of them dispersed throughout the ocean too.

Plants. The answer is, and always has been, to stop emitting additional carbon from fossil fuels, restoring ecosystems, and letting plants and algae and natural carbon sequestration mechanisms do their thing. It also feels pretty inarguable that making that change would be possible if literally everyone on Earth went "yeah, let's do that."

[TeMPOraL]

And of course the counterpoint is, plants don't sequester carbon, they only buffer it. Plants are carbon-netural - they release what they stored as they decompose. Being self-replicating and something we have lots of experience with are good features, but to turn this into a carbon sequestration mechanism we need to have a program of continuously cutting these plants down and storing them in places the air can't reach.

[qchris]

Those mechanisms do already exist--marine snow, compacted biomass in wetlands, heck, even things like whale falls store carbon for enormously long periods of time.

The buffer duration/cycle period matters significantly. I agree, turning every bit of carbon released into sticks n wildfire zones won't solve the problem, but in the current situation a) buffering will make a difference in the short term, and b) there are natural mechanisms that do sequester carbon on a functionally permanent basis and keeping those functioning or adding to their capacity through ecological restoration is extremely important and doesn't require new technology.

[notabee]

We are burning the equivalent carbon of millions and millions of years of plant growth, trapped in fossil. Our current available plant mass, even if we cover every square inch of the earth with vegetation, cannot absorb millions of years of carbon. As another poster has replied, plants also release that carbon back when they decompose, unless they are buried. The only answer to digging up millions of years of dead organic matter and burning it is to suck it back into the ground, or fire it into space, or anything else that actually removes it from being recycled in the biosphere.

[Retric]

There is only really one option to store it, underground.

Now you might ask if that’s in pure carbon, CO2, or dead organisms but that is just an economic question. While multiple options exist picking one is far less difficult than funding it’s implementation.

[throwaway0a5e]

>Where do you store it?

Someone creates some magical building material that is high in carbon, non-reactive (or at least doesn't leach carbon into the air), economically viable and is mostly recyclable.

Imagine something along the lines of synthetic high carbon asphalt or masonry products.

[Retric]

A lot of CO2 has been released.

10 Trillion metric tons / 7.8 billion people ~= 1,300 tons per person which is well beyond the amount of building materials used.

[TeMPOraL]

Yup, but the point is that with such magic building material, we could not only build buildings and facilities with it, we could just pile heaps of it above ground for the purpose of only sequestering carbon.

[bryanlarsen]

That's about 130 trees or 13 houses. Yes, that's well beyond the amount of building materials used, but not unimaginatively so.

[lostapathy]

How much pavement exists per-capita? I'm sure that would lower the multiplier a lot too.

[bryanlarsen]

In case anybody missed the subtlety here, I assume that throwaway0a5e is talking about wood and similar products such as bamboo.