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by twic 2684 days ago
A quick google suggests that this is an active research topic. I have only skimmed this paper, but they find that logging is net emitter of CO2:

https://cbmjournal.biomedcentral.com/articles/10.1186/s13021...

Interestingly, they account for carbon emission from the wood produced by logging ("sawnwood"):

Sawnwood decay is approximated with an exponential decay [with a half-life of] the normal distribution truncated at zero with mean equal to 30 and standard deviation equal to 15, according to IPCC guidelines. So far, no life cycle analysis has yet been done for woody products in the tropics and adapting the framework developed in Europe and North America in tropical countries remains challenging.

So they assume that the average bit of timber lasts thirty years before giving up its carbon, and only about one in six lasts longer than 45 years. I suppose the lifecycle of wooden manufactured items tends to end with them being burnt when they're worn out.

If i am reading the graphs correctly, then wood going to the sawmill is only a small part of the carbon emitted by forestry, and they mention that only one-third of the wood entering a sawmill leaves as sawnwood, the rest being lost as sawdust, so even if you could preserve wooden items for ever, it might not move the needle much.

On the other hand, if you could collect all the sawdust from the mill and bury it, or make it into biochar and then use it as a soil amendment, that might.

Anyway, that is one paper amongst many, go forth and read if you're interested!

3 comments

> So they assume that the average bit of timber lasts thirty years before giving up its carbon, and only about one in six lasts longer than 45 years. I suppose the lifecycle of wooden manufactured items tends to end with them being burnt when they're worn out.

That seems like a pretty bizarre set of assumptions. Wood doesn't just disappear in 45 years unless you leave it in the open untreated.

As i wrote in the paragraph you quote, my assumption is that this models wooden items being burnt at the end of their useful lives.

But hey, don't take my word for it - in the paper, that bit references this:

Penman J, Gytarsky M, Hiraishi T, Krug T. Good practice guidance for land use, land-use change and forestry. Intergovernmental Panel on Climate Change (IPCC), chapter 3, Appendix 3.A.1.3. UNEP; 2003. p. 268–70.

Which you can read here:

https://www.ipcc-nggip.iges.or.jp/public/gpglulucf/gpglulucf...

https://www.ipcc-nggip.iges.or.jp/public/gpglulucf/gpglulucf...

So dive into the gory details of harvested wood products, and the basis for their future methodological development to your heart's content!

It sounds like the answer basically depends on how we log and what we do with the produce, but it could be made carbon neutral or even negative with the right approach.

Makes me wonder just how much polymer use we could replace with wood, and what kind of disposal techniques for it we could develop to increase carbon sequestration (e.g. instead of burning it, bury it deep?).

There needs to be more talk about biochar...