Edit: fuck it, I’ll just do the math again. See the bottom.
They keep confusing the issue because they keep talking about storage. Because their underlying motivation is to have more old growth trees, and to pull carbon from the atmosphere as a secondary effect. Which hey, I get, they’re beautiful. But it’s still BS to say old growth is extracting carbon from the atmosphere faster than new growth.
To see for yourself, use that table they made and take ‘estimated total carbon’ and divide that (tons) by the estimated stand age. That gives you tons of carbon per year of stand age. The really old growth stands with the impressive (overall) carbon numbers actually have really terrible (relative) tons/year numbers. Like the first one is ~ 2.3 tons/year. Where if you go to the new growth stand and ignore year zero (because that has a super high number/divide by zero), it’s 13 tons/year. About ~6 times higher.
And note, it has to be that way. If you took the rate from the new stand, and multiplied it by the stand age for those old stands, the whole forest would have to be solid carbon with no air or gaps.
And unlike those old growth stands, the new growth stand is also producing useful-to-humans output like lumber as part of that calculation, where old growth stands will be nature preserves in this calculation.
In my experience, it’s useful to think of forests like a carbon ‘spring’, or even dam. They aren’t (generally) sequestering it the way the word tends to bring to mind (locking it in a warehouse somewhere maybe). Wood wants to burn in our atmosphere, especially dry and dead wood. If enough of it builds up, eventually that spring will release, or dam will break/overflow, and that carbon goes right back into the atmosphere. Usually in a catastrophic fashion.
Harvesting it and putting it somewhere it won’t rot is like releasing that spring or the water in the dam, without breaking anything.
Regarding your comment on chopped down forests not being fire resistant - it’s actually the other way around. Non-existent trees and brush can’t burn.
Additionally, not harvesting timber from most forests results in overgrown and sick trees, which are a nightmare forest fire wise. It’s why california (and other western states) keep catching on fire so badly, because logging has been so heavily restricted. I’ve done thinning work, and it’s night and day from disease and fire risk. Almost impossible to burn a forest after it’s been done, and it doesn’t want to.
Before that, it was a complete tinderbox.
Now don’t get me wrong, clear cut logging followed by terrible replanting and management practices are certainly be worse (fire wise) than just letting an old growth forest be. Especially since those tend to be in consistently very wet areas that don’t like to burn. But that isn’t how it’s been done in a long time, outside of perhaps random bandit operations.
In California’s climate, it requires cutting down a significant portion of trees and removing built up brush (or doing a controlled burn), or the whole thing turns into a mini-nuclear explosion waiting to go off.
Also, most of their numbers actually seem weird to me though, because as far as I’m aware, more independent data actually shows even newer growth at more like 1.5 tons/year on average across the US.
Edit - here comes some math (different links this time)
Ok, so the US Forest service says that research shows forested land in the United States sequestered 775 million metric tons of carbon/yr [https://www.fs.usda.gov/research/sites/default/files/2022-04... ], and also that the US has 819 million acres (approx.) of forested land.
Which is approx. 1/3 of all US land cover.
Notably, I don’t think that is discounting carbon released due to wildfires in those lands, but I might be mistaken.
That also works out to (on average) 1 metric ton of co2 stored per acre per year on forested land in the US.
If I remember correctly, another 1/3 of the US by landmass can be considered arable (there is overlap), aka can grow things, with some work.
The US EPA says that in 2021, the US released 6,340 million metric tons of fossil carbon, which was a notable decrease [https://www.epa.gov/climate-indicators/climate-change-indica....]
That means all US forested land sequestered enough carbon to represent a little over 10% of one years co2 emissions per year. Doubling all US forestland would therefore account for around 20% of each years co2 output.
If we figured we could double again efficiency by using fertilizer, etc. we’d still be stuck at only 40% of each years co2 output. And we’d starve, because we converted all our farmland to forests and those trees are generally not a good source of nutrition for humans. Also, we’d have to kill all the cows/pigs/etc.
So barring turning every forest into some sort of super productive co2 farm somehow, and converting all available fertile land in the US to do it while somehow not starving to death - I don’t see how we’d even pass 50%. And even then, I wouldn’t take that bet. :(
That hopefully also provides a more useful idea of the scale of the addiction humanity (and the US in particular) has with fossil carbon, when we’re digging up and burning the equivalent of 10x the rate our forests grow, every year, and we’re one of the top 10 most forested countries in the world.