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Comment by egypturnash | Hacker News Reader

> The other thing is that the entire pathway can now be put inside cells, either normal bacteria like E. coli or the synthetic cells with a minimal genome that researchers are working on. If that's the case, then the need to supply all the chemical co-factors should go away, since the cells should be producing them anyway. More importantly, if the cell is made to depend on this pathway as its only source of carbon, evolution would have the chance to optimize it even further.

Immediate thought: What happens when that bioengineered E. coli or whatever, which you're hoping evolution will make work even more efficiently, leaves your carbon-sequestering vats and starts reproducing in the wild? Eventually you reach a point where we're getting record low CO2 levels. Hello, new Ice Age.

(I am sure there are many reasons this would not happen but it certainly makes for a nice bullshit explanation if I wanted to write a story set in a far-future ice planet.)

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> bioengineered E. coli or whatever, which you're hoping evolution will make work even more efficiently, leaves your carbon-sequestering vats and starts reproducing in the wild? Eventually you reach a point where we're getting record low CO2 levels.

Normally, if you want to create something like this, it's an auxotroph. So it shouldn't survive outside of the carbon-sequestering vat.

Or it's all on a plasmid, so once it's out of the vat plasmid won't be maintained.

Or these will be created in "Synells" [0] that can't really replicate.

Though that's a really interesting thought. If we find a technology to do anything about CO2 levels, it seems plausible that we're going to accidentally go too far in the other direction.

[0] http://www.nature.com/nchem/journal/vaop/ncurrent/full/nchem...

I know it sounds far-fetched, but if someone develops a technology that can rapidly grow a wood-like material out of atmospheric carbon in such a way that entire buildings can be grown in single digit years, we could start seeing countries fighting over who is using too much CO2 and consuming too little

Future environmentalists:

We need to drill in the ocean in order to flare more CO2 into the atmosphere or sea levels will drop to catastrophic levels!

Not exactly what you're asking for, but intriguing nonetheless:

http://inhabitat.com/phillip-ross-molds-fast-growing-fungi-i...

I've been meaning to try and do an estimate related to this. Just how much CO2 could be pulled out of the air by _extensive_ farming of fast growing trees. We could find ways to use as much of the wood as possible (construction materials, etc.), and just sink the remaining wood in cold water where the carbon would stay locked away for 100+ years.

Nvmind, ran the numbers... this plan sucks.

Then again, if my numbers are right, if humankind dedicated <1% of land used worldwide for food to growing trees and locking away the cellulose, we would cancel out worldwide CO2 emissions. Since most of that land is used as pasture, there is more than enough play to keep the world fed, and I could see up to 10% being tasked to this purpose , which seems doable in an emergency.

I'm confused...the numbers sucked for extensive farming in order to cut CO2, but only 1% of arable land would cancel CO2? What am I missing?

I initially thought it didn't look good when looking at the amount absorbed yearly per tree, but then was surprised by some estimates on how many trees you can fit per unit area. A more accurate estimate needs to be done though, different numbers I found put the final range at about an order of magnitude.

Also, most farming and stable forests are mostly carbon neutral. This would require continual seeding, harvesting and sequestration of the cellulose. Maybe it will be a good thing though that cellulose+lignins are so hard to breakdown.

Still plenty of room at sea. Is there a fast growing mangrove?

Have you accounted for moving the trees from where they grow to where they can be used? (E.g., milling, planing, curing.) That will take energy that likely offsets some of the benefits.

Likewise, moving the lumber or finished goods to consumers will also require some energy that might offset the carbon removed.

Normaly - nuclear plants are safe.

But on humans, they aint. Humans & Technology- not even once.

Not gonna happen. Releasing these "into the wild" is like releasing glow in the dark rabbits that only eat arugula. They'll die before they make it out of the drain, let alone before they make it to any natural microbial ecosystem where they were be viciously torn apart by organisms finely tuned to that environment.

They only need to survive long enough to swap genes with existing bacteria.

https://en.wikipedia.org/wiki/Horizontal_gene_transfer

Two reasons it won't end the world.

1. This is in vitro work, and even there it is only 5x as efficient. In vivo I'd expect that rate to go down.

2. Metabolism is expensive. This is probably not a very fit pathway. It takes a lot of energy to produce the proteins and ATP necessary to power this cycle and it's product isn't more ATP. It would incur a substantial fitness cost and in the wild it would likely get out grown by wild bacteria that favor Glucose producing photosynthesis.

Not that a new ice age couldn't happen, but carbon fixation is already at a evolutionary local maximum among the six different wild versions, so I don't see why a 7th would be any different.

Then we chop down all the trees and burn them!

Indeed. One way or another, I think recent years have established that "not enough CO2 in the atmosphere" is a pretty easy problem to solve.

Party like it's 1999.

Free Corvettes for everyone :-)

Infinite apple juice!

It depends.

One of the things that makes Earth special is the formation of carbonate rocks by life taking CO2 out of the atmosphere and falling to the bottom of the oceans; these rocks are then subducted by tectonics and the CO2 spewed out by volcanoes.

As the Earth's core cools, volcanism will diminish, and so the recycling of CO2.

But perhaps Nuclear fusion can fix everything... However I am not a geologist.

>(I am sure there are many reasons this would not happen but it certainly makes for a nice bullshit explanation if I wanted to write a story set in a far-future ice planet.)

You are a bit too late to the party:

http://www.imdb.com/title/tt1706620/

Assuming they managed to make some kind of bug that was viable outside of the lab, we genetically engineer a spider to eat the fly. Obviously, this kind of thing has the potential to get out of hand as the technology improves and becomes more accessible. Maybe this is the Great Filter, or maybe the filter is not having a full enough understanding of things to solve problems before it inevitably becomes garage-level science.

I had same thought except with an all trees will suffocate plot twist. The ice age angle is interesting.

We will just burn more and more ...

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