"At that price we’d be better off just planting a bunch more trees instead."

Ugh. No, we wouldn't. Planting trees doesn't solve anything. If water is flowing into a bathtub faster than it is draining out, you do not solve the problem by making the bathtub slightly bigger. If you don't change the inflow or outflow, a one-time increase in the amount of storage doesn't do anything except very slightly delay the crisis.

Trees are NOT "the lungs of the world." A mature forest is carbon neutral. For trees to work as a carbon sink, you'd have to cut them down as soon as they mature and then preserve the wood in some way so it can't burn or rot. This is simply not a scalable way to reduce carbon flows. It's too slow, it's too expensive, and what do you do with all the leaves, wood, and other debris?

If you want to do bio-extraction, at least do it in a way that makes sense. Grow something cheaper, faster growing, and much easier to sequester. For example, we could grow Azolla on vast shallow ponds adjacent to the Arctic Ocean every summer. Azolla floats and grows insanely fast in 20+hours of sun, with no fertilizer. When the ponds are covered, open the gates and let the whole mass flow out to sea, where it will die in the saltwater and sink to the bottom.

This is how nature did it. It's very probably how we got from "hothouse earth" to the current climate. There's a thick layer of mud at the bottom of the Arctic that is basically a solid mass of preserved Azolla, containing teratonnes of carbon that used to be in the atmosphere.

Once you have shaped the ponds, it pretty much works for free anywhere you have north-flowing rivers and streams. And, unlike adding to the fixed *stock* of carbon in trees, it would increase the annual *flow* of carbon out of the atmosphere.

The international economic effects of such a system would be interesting too. Most of the first world would need to charge a carbon tax or otherwise find a way to pay Russia and Canada to extract and sequester carbon for them, although the U.S. might be able to do much or all of its own carbon extraction and sequestration along the north and northwestern edge of Alaska. Over time, as the West passes carbon neutrality and into negative net carbon flows, it will become politically unacceptable to ask the West to carry the whole burden. At that point, developing nations will need to get to carbon neutrality either through renewable energy or by charging a carbon tax and contributing to the extraction and sequestration process.

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Feb 9, 2021Liked by Noah Smith

How I hate using images of cooling towers pouring water into the air as a statement about pollution. The bad stuff emitted you can't see. Picky Picky Picky old and failed engineer.

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This is the optimistic take (which is what I’d expect from you, Noah).

Kevin Drum, seeing absolutely zippo collective progress in decreasing CO2 emissions despite the science showing that climate catastrophe was looming even as far back as the ‘90’s, is far more pessimistic:


He thinks that we’ll have to seed sulfate aerosols to block the sun in coming decades in desperation despite unintended effects.

In general, he’s more optimistic about American democracy but less techno-optimist than you. Maybe because he’s an older guy who has cancer.

In this case, Drum may be more on the money.

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1. You can't hold people _morally responsible_ for actions commited before those actions were generally recognised as a moral wrong.

Climate Change wasn't on the agenda before, say, 1980. It's obtuse to ascribe emmisions before that.

2. You can't hold people _morally responsible_ for things their ancestors did.

3. If you're going to do this CO2 legacy stuff, you need to discount early emissions by planetary sink capacity.

4.... and why start at industrialisation? Why not count breathing and log burning from the year 0?

5. I look forward to an article which considers what the economic state of the rest of the world would be if the west hadn't industrialised, and properly ascribes the West a credit for it's innovation and capital accumulation.

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One thing I like to add is that you as a citizen of rich country hugely benefits from what your ancestors did so it isn't just "pay for one's ancestors’ irresponsible lifestyles"

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You may find this paper interesting. It proposes a method of Antartica dry ice based CO2 capture that would be doable with current technology. https://journals.ametsoc.org/view/journals/apme/52/2/jamc-d-12-0110.1.xml

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Here's something I've wondered. Could DAC infrastructure be dual-purposed to pull other pollutants out of the air? Given the massive public health benefits of reducing regular old smog (and such), that could seemingly create a huge additional benefit to weigh against the cost, help curb intra-US climate injustice (if the big dual filtration plants were smartly located), and maybe even get China on board, since they seem quite concerned with old fashioned pollution. I have no idea how this would work technically. But it seems like, if you're already building the massive fans, why not filter the air as, or just before, you pull the carbon out of it...

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Where are you on Nuclear Power?

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The most important thing rich countries can do is spend as much money as possible in clean technology. Where it exists we need it to be as cheap as possible. Where it doesn’t we need to find a way.

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Does anyone know of an article or post that explains the science of carbon capture? I'd like to understand the thermodynamics of it. Why exactly is it so hard? Is it entirely a function of the sparsity of CO2 molecules per unit air, or are there chemistry reasons too? Is the CO2 spread smoothly through the atmosphere or is there more of it at certain layers? What is the lower bound on how much energy is required to sort air into CO2 / non-CO2 components? Etc. I've never managed to find a good resource on this.

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Two things (that contradict):

- The more we can do to reduce the chance of high temperatures, the better. So, in this sense, I'm all for carbon capture, as the IPCC report spells out just how beneficial incremental differences in temperature reduction can be - less chance of drought, wild fires, etc.

- Admittedly though, I'm concerned carbon capture may become an excuse to allow for more fossil fuel consumption than would be the case if all externalities were reflected in the price. Specifically, my concern is fuel prices will only reflect the price of greenhouse gases, which don't necessarily reflect the impact they have on public health. Additionally, I'm curious as to how these carbon capture projects get funded. Does the US government fund the projects? If so, are we socializing a cost which should have been proportionally been borne more by industry?

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Carbon capture is silly when proposed as a way to make coal plants green, but it seems that for something like cement manufacture, it would make sense to capture the CO2 as it comes out of the kiln. Direct air capture from open-air atmosphere seems like it shouldn't be the first resort, although a lot of it will be necessary.

I think it would make sense for SpaceX (and the rest of the launch industry) to commit to using synthetic air-capture fuels since it would help grow the early market for air capture and likely barely budge the cost of the launches.

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