Canada's forests emit more carbon than they absorb

And the forest fires and beetle vulnerability are not unrelated to current climate change (at least in California last I read), so that might help close the non-anthro-centricity argument they are using for different accounting methods.

Yeah, I'll concede that's pretty good.

I like this, although it's a bit ambiguous whether it's the forests or Canada as a whole that experienced a "net carbon emmissions".

I asked below but maybe you'll know the answer. Basically insects/bacteria cellular respiration produces CO2 just like us ?

update: found some answer https://www.amentsoc.org/insects/fact-files/respiration.html

I never considered that.

Also, how unlikely that this CO2 is reabsorbed by the plants (granted that can only occur after winter when leaves are back) ?

But not necessarily released as CO2, which is what "re-emitted" means to me. If it goes atmosphere -> tree -> fungus -> bits of fungus buried in the ground for millions of years, that's effective sequestration.

As said below, it's not C, but CO2 we were worried about. Also I admit that I don't know if humus organism produce CO2 from wood remains.

This is true only in part.

We have found shells, made of Calcium carbonate, still relatively intact more than 3000 years after the death of the animal. Some shells had last for 500000 years (See Nature 2014-dec-03)

Under the sea there are entire ecosystems based in dead shells.

While you bring up an important forestry mgmt issue (overgrowth of underbrush) I don’t think they count individual trees but rather surface area coverage.

That really depends on the state/region. You can see in this [1] report that states like Florida and Georgia are burning millions of acres a year in prescribed burns, while California burns a few ten thousand.

[1] http://www.stateforesters.org/sites/default/files/publicatio...

depends on what those logs are for. if they are for building houses, then probably yeah

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!

The term "global warming" appears nowhere in tfa. That of course does not mean it isn't the case but it does mean that you are mistaken.

More critically, they emit huge amounts of sulphuric compounds, which are what really sick around and tend to cooling. Unfortunately when those same compounds don’t reach high altitudes, you get a lot of acid rain. All told however, their net effect is strongly cooling over the first few years, and then milde cooling over longer time frames.

Reminds me of global dimming.

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

The problem is that, in a market economy, like the one we live in, we can dig up and burn coal much faster then we can grow and bury trees.

Coal can be mined for $30/tonne. That's 3 cents/kilogram. At that price point, it's nearly free. How can you keep up with sequesteration, when you are competing with nearly-free?

Sequestration makes sense when we are talking about an economy that derives ~5-10% of its energy from liquid fossil fuels, and everything else from renewables. It doesn't make much sense when 50% of energy generation comes from fossil fuels. It's just too labour intensive to make it work.

The duration is important because you can only grow and harvest a finite amount of wood each year, because trees can only grow so fast. So if you harvest the maximum amount of wood possible each year, W, and it lasts for 10 years, you have sequestered 10 x W units of carbon; if you use it in ways that lasts 20 years before it needs to be replaced, you have sequestered 20 x W units of carbon.