I often hear science-adjacent folks stating that a tree needs to be 30 years old before it starts absorbing CO₂, usually paired with the statement that it’s therefore pointless to start planting tons of trees now for slowing climate change.
Now, as far as my understanding goes, the former statement is very obviously nonsense. As soon as a tree does photosynthesis, it takes carbon out of the air, which it uses to construct cellulose, which is what wood is made of.
Really, it seems like it would absorb most CO₂ during its initial growth.
I understand that it needs to not be hacked down + burnt, for it to actually store the carbon. But that would still mean, we can plant trees now and not-hack-them-down later.
I also understand that some CO₂ invest may be necessary for actually planting the trees, but it would surprise me, if this takes 30 years to reclaim.
So, where does this number come from and is it being interpreted correctly? Or am I missing something?
Edit: People here seem to be entirely unfamiliar with the number. It might be that I’ve always heard it from the same person over the years (e.g. in this German video).
That person is a scientist and they definitely should know the fundamentals of trees, but it was usually an offhand comment, so maybe they oversimplified.
I coudn’t find a source for your statement, but I did find that it takes a tree 30-40 years to store a ton of CO2, so maybe that’s what they mean? A tree will store carbon as it grows, because it builds itself with carbon from the air. https://ecotree.green/en/how-much-co2-does-a-tree-absorb
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The mass of a tree is composed of carbon fixed from CO2, so it doesn’t make any physical sense for a tree to grow at all without absorbing CO2. This is nonsense, trees begin fixing CO2 the moment they start growing.
In the US PNW coast area Douglas Fir trees are harvested for lumber within about 30 years, plus or minus. Maybe the person you were talking to was considering the harvest of the tree to be the moment when the CO2 is “reclaimed”?
Wrt to when the tree pays off the carbon footprint generated by raising and planting the seedling, I guess it’s less than three years.
Fun fact: Douglas Fir reach peak carbon fixation rate at about 120 years.I highly question this. A Dougie at 30 is about a foot across. I just took 7 Dougie’s down on my lot, the largest was 24in at chest height. I can see Puget sound from my place. In fact, I actually counted the rings on one of them and it was 101 years old. Shit. Now I’m gonna go look and measure the 30. I dyed every fifth ring when I counted it initially.
K, so at 30y/o the only stump I left in the ground was only 8.5 inches across and 20in in diameter at 101, so that’s an easy 24in with the bark. The tree was 120ft tall when I felled it in July. A real shame too, I wanted to keep all of them but fire damage. The next day beetles had already hit all of them. I dropped the trees a week after the fire and debarked them to help protect the wood before i could mill them, and there were hundreds of beetle tracks under the burned bark. Pine beetles live under the bark, in the cambium, no bark=no beetle. But the California wood wasps showed up the day I dropped the bark. Those things are terrifying, jet black, 2.5 inches long with an inch long stinger on top of that, so about the width of your palm. Adult pine beetles are about 3inches long when they emerge too. Wicked little fuckers, the both of them
Volume of a cylinder is πr^2Height
Assuming the height of the tree stays the same, let’s say 100’.
Radius is 2’ and then we have a 500 year old with a radius of 5’
2’ x 100’ tree has a volume of 1256’
5’ x 100’ tree has a volume of 7852’Trees are made of carbon. Older trees sequester more carbon
Young trees of many species also grow faster, though, and if the old tree dies and decays all that carbon returns to circulation. Forestry, done right, actually is carbon negative. However, it’s also incompatible with the critters that need old-growth forests (and old growth itself soaks up carbon fairly slowly). Environmentalism needs to get better at appreciating tradeoffs IMO.
Something you are missing is that, at night, trees respire. That is, they take in oxygen and release carbon dioxide.
Now I’m not sure of the whole 30 year thing, but perhaps that’s part of the calculation.
I think the simplest answer is - they are wrong.
Trees’s structures are made up largely from cellulose and lignin (https://en.wikipedia.org/wiki/Lignin - for the chemical structure).
Both are very rich in carbon.
The next time someone says that to you - point to a tree and explain that - that thing over there is largely comprised of carbon that has been extracted from the atmosphere by photosynthesis- so what are you talking about?
Yeah, it’s the simplest answer, and likely correct. But a more interesting question is why they got it wrong and what assumptions and misconceptions did they make to arrive at the wrong answer.
They may respire, but they must absorb more than they respire, because that’s where the wood comes from…
I suppose it’s more of a "that’s when they start binding the meat of the lifetime-CO2-stored. Remember, trees also burn quite a bit of their previously fixated CO2 for energy. Perhaps the amount of CO2 fixed in the first 30 years pales in comparison to that of the next 30?
Could be sort of a “break-even” point? Assuming it’s even true, which is a pretty big assumption. You could ask them for a source next time if you hear it often, because I’ve heard it precisely 0 times before.
Yeah, last time I heard it, it was in this German video: https://piped.video/watch?v=ThqfNX8EMe4
(I did not note down the timestamp, sorry.)As I understand, the guy has a PhD in forensics. Obviously, not quite his field of expertise, but I’d expect a biologist to know how a tree works at a basic level.
I have watched other, similar videos of the guy before and since people here seem to not have heard this number before, I’m now consider that it was maybe always this guy who said it. I’m sure, he has some source for it, but it was an offhand, somewhat cynical comment, so maybe he oversimplified…
I usually hear the opposite, that growing trees absorb more, I mean that’s what I hear when I talk about the Christmas trees
I guess people find the argument in favor of their own comfort, I never checked the facts actually so… I’m not doing better
It’s true. And christmas trees would be fine if they’d end up in long lasting buildings and wouldn’t need a lot of fertilizer which usually is made from oil.
Has a little calculator you can play around with to see how much carbon is captured by a tree based on various factors.
Not your fault, but that is the most annoying calculator I’ve ever encountered, as someone who uses the metric system.
I mean, what kind of maniac describes the amount of oxygen produced in pounds?
Also are those US gallons or UK gallons?
The increments used for the circumference of the tree is also incredibly weird, 7 and 3/4 inches? Really? Clearly converted metric to imperial. Why not include a slider to switch to metric, if that’s what you’ve based your numbers on?
It’s a website written by an American for an American audience, which means the writer uses inches, pounds, and US gallons.
No need to feign surprise that Americans generally don’t like the metric system.
7 and 3/4 inches is (roughly) 20 centimetres.
Why not use 10 inch increments or even 6 inch increments if you’re making a site for an American audience?
It’s like car sites and manufacturers which list the 0-60 time, but it’s actually the 0-62.14 time.
If you’re going to use imperial, use imperial. Don’t do a half assed conversion from metric.
I am also available if anyone wants to listen to a rant about ecoflush toilets.
Probably because the writer is not reporting her own original research. She is reporting work done by others, they often used metric, and any metric units were converted to common US units because the article was intended for a general American audience.
And why isn’t there a button to restore the original metric units? Same reason why when a newspaper reports a translated quote from Macron or Putin or Xi, there is usually no button to restore the original French or Russian or Chinese: the editor decided that it wasn’t necessary for the intended audience.
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*Arse.
Your welcome. /s
Young people - “Oh my god, old people believe everything they read on Facebook”
Also young people - "Some random guy on YouTube said it and I trust him so it must be true "
That’s the end of my Lemmy comment, don’t forget to smash that like button
"Some random guy on YouTube said it and I trust him so it must be true "
OP is trying to fact-check what he heard, though. You could give a little more credit.
I don’t know why you’d believe that I’m young, nor why this would be a random guy on YouTube.
Unfortunately, I am very bad with technology and accidentally hit the wrong button on your comment.
I subscribed and hit the notifications button
