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.
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…
Not necessarily. The two things aren’t related. You yourself burn way more calories in a year than you store in your body or use for growth. Respiration is not just about growing. It’s about using energy for cellular processes: immune system, transporting chemicals around the organism, replacing old cells.
An organism can grow at one rate and use energy (expelling CO2) for other functions at a different rate. They aren’t really related.
They are related, because the energy they use and the mass they grow both come from absorbed CO2.
In other words, every molecule of CO2 expelled by a tree was previously absorbed by the tree. Unlike humans, energy use by trees is carbon neutral. Which means trees cannot grow unless they absorb more CO2 than they expel.
That makes sense. I didn’t think about it that way.
I’m not sure, why you’re interpreting my comment as a general statement. I’m specifically talking about trees. While it’s theoretically possible that they get carbon from the ground and actually respire more into the air than they absorb, while also growing wood, that would be extremely surprising to me. Unless there’s data supporting it, I don’t see why we should entertain the thought…
On average they emit around half the carbon they absorb so this wouldn’t explain that fact.
It’s almost definitely false.
That makes no sense. The human body is on average carbon neutral. You eat carbon and then you excrete it. Same as trees. Except you don’t continuously grow like a tree for potentially centuries.
Taking solid carbon in food and turning it into CO2 is not carbon neutral.
Of course it is. No carbon was created. And unless you’re putting on weight, your mass stayed the same. Carbon in, carbon out. I’m not talking about CO2 neutral.
Wtf? You can’t make up your own definition of “carbon neutral” and then make arguments about it on the internet.
Yeah, no shit, but that’s not what the rest of us are talking about.
I’m not making up any shit wth? How dense are you? A tree is carbon negative because it sequesters carbon continuously. A human adult is not, it’s carbon neutral - when observed in isolation. The human system is carbon neutral. It doesn’t matter where the car on comes from. You expel the same amount as you injest. I think honestly you’re the one who doesn’t understand what carbon neutral really means.
Turning carbon in the environment into CO2 by oxidizing it is NOT carbon neutral! If that was the case, then every car, plane, and coal power plant would be “carbon neutral”. That’s very obviously not the case.
It’s ALL about CO2! For the love of god, go read some articles. You have no idea what you’re talking about.