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Comment by aivisol | Hacker News Reader

> However, by definition, the sailing ship is not a carbon neutral technology. For most of history, sailing ships were built from wood, but back then whole forests were felled for ships, and those trees often did not grow back.

I do not understand this sentence. If I cut down a tree and do not burn it, isn't it a carbon neutral process? It did not release any carbon into atmosphere. By this logic is there any material to use to build something which is neutral?

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The thought could be that in "tree form", the material contributes to the net uptake of carbon from the atmosphere, so once it is harvested that negative flux on the balance sheet shifts equilibrium more towards lower or net negative uptake. It's relative.

That's not true though, the tree stop growing at a certain point and is really carbon neutral until it dies and decays into the ground and new ones replace it.

By removing trees and planting new ones, this process is sped up and more carbon is removed from atmosphere.

During the age of sail most of those forests were cut down and turned into farms or pasture-land. So there was a net increase in carbon emission just from the expansion in human activity.

If you were going to build a farm there anyway, then it’s better to build a ship out of that wood than to burn it down.

Plus, it's my impression (it could be very effective marketing by the lumber industry) that lumber trees are quickly grown and chopped in farms and controlled logging. And the next tree is planted.

I'd guess that construction is probably a pretty good sequester for the wood/carbon in terms of length of service, and likelihood for controlled recycling or burial after its done.

The logging industry is likely incented to maximize the carbon sequestration rate: which is growing trees producing future lumber.

It will eventually rot and release its captured carbon.

All trees, even those which are not cut down for constructing a sailing ship, also eventually rot and release most of their captured carbon. Only those which are burned efficiently in a high-oxygen environment turn completely into CO2.

In a natural forest, it's true that a tiny fraction of this biomass derived from atmospheric CO2 rots incompletely on the forest floor and is turned into a small amount of carbon-rich soil, but this process is glacially slow. [1] suggests single-digit grams per square meter per year. Rotting on the seafloor may or may not be any better or worse.

Relatedly, carbon sequestration projects have biological carbon intake as one option. Instead of using industrial-scale chemical or electrical reactions to pull carbon from the atmosphere, use photosynthesis. Grow some trees, process them into ethanol and graphite, and bury the carbon-rich waste forever.

[1]: DOI:10.1007/978-3-540-92706-8_11 https://www.researchgate.net/publication/225314103_Soil_Carb...

Tree contains X Co2 => Tree gets cut down without replacement => ship gets made and rots => X Co2 releases into atmosphere. Net Co2 = +X

Tree contains X Co2 => Tree dies => New tree grows in opened up space. Net Co2 = 0

Why do you assume the tree would not be replaced, we plant more trees than we cut down nowadays for example. The only reason to not replant the tree is if the land was being used for something but then the tree would have been cut down anyway ship or not.

The original quote at the top of this thread says that ships were build from trees that were felled _and not replaced_. The discussion started from that assumption.

Anyone interested in a fair comparison should point out the error of that comparison. Using wood in a managed forest it’s not a bad thing. It’s greatly preferable to extracting coal and oil.

So what? That’s part of the natural CO2 cycle. The problem isn’t carbon dioxide. The problem is adding CO2 from fossil fuels. As long as there is a net growth forest there is no problem. Just make sure you replant trees cut down. It is more important that we start extracting coal and oil.

A human-managed forest and a naturally evolved forest are very different things. When we plant trees, it's basically another farm, rather than the rich ecosystem that was originally there and destroyed by us. They also have very different carbon dynamics. The only way to recapture that same level of carbon that the original forest had, is to "rewild" the land and allow a full, old-growth style forest to grow back, which takes a lot longer than just planting some fast-growing trees in straight lines.

"by definition" of what? Carbon neutral or sailing ship? Neither term is defined in the article, and neither interpretation makes any sense.

The tree is no longer alive to photosynthesize co2.

A tree cannot live forever. Once it is dead all (or almost all) accumulated carbon slowly released back into atmosphere as CO₂ by bacteria. So cutting trees and preserving them from decay is a carbon negative process in a long run.

how is it carbon negative? wouldn't it be neutral? unless the trees were sent underground to prevent release into the atmosphere? or became petrified?

If I keep cutting down and re-growing trees on the same plot of land over and over again I will reduce the total CO2 in the atmosphere as long as the cut down trees are not burned or rot. You can avoid that by building houses for instance. Or boats.

That what I meant in my comment, but over long enough time frame it will be a carbon neutral process: a building will eventually fail into disrepair and will rot or will be destroyed by a fire. A ship will likely last even less.

Anyway I see no reasons to avoid using wood if it is harvested responsibly.

Correct: to make a change we would have to bury millions of tons of valuable wood deep enough that the co2 stays trapped. In short, it would be the opposite of extracting and burning oil.

It only takes up Co2 in its growth phase, not afterwards.

That seems intuitively true, but apparently it's still debated whether old- or new-growth forests are more carbon-negative.

It is really only a debate about when exactly trees stop growing and consuming CO2. Given enough time, sooner or later the tree isn’t consuming CO2. At that point there is no point in leaving the tree standing. Cut it down and let a new tree grow there.

Yes, but a tree that isn't growing isn't trapping much carbon dioxide either.

Yes, and it is not releasing fossil carbon.

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