"I'm not sure I understand... ... The plantation being cut down and then regrown has 0 net impact"
Yes, that's correct - that plantation, in itself, has zero net loss of carbon once it regrows.
What you're missing is the activity in the meantime that contributes carbon to other cycles of carbon heat trapping.
So when all is said and done, sure, that forest is back where it was with the same amount of carbon - but the permafrost it helped melt (with accompanying release of methane) is still melted.
If at every moment someone is selling a stock, someone else is buying it, this argument would say the stock is worth zero. Because for every person trying to buy it for X someone is “buying it” for -X.
But of course, X is what matters. That’s how we calculate market cap and it measures overall effects
> Because for every person trying to buy it for X someone is “buying it” for -X.
Selling “it” for X is not buying “it” for -X. It's buying X for “it”.
More specifically, if A sells X to B for Y, A gives up X for Y implying Y is worth at least X to A (and X at most Y), While B gives up Y for X, implying that X is worth at least Y to B (and Y at most X.)
Hence, that trade occuring in market where X and Y have access to all potential purchasers and sellers of X and Y fixes the value of X equal to Y.
Yes, that's correct - that plantation, in itself, has zero net loss of carbon once it regrows.
What you're missing is the activity in the meantime that contributes carbon to other cycles of carbon heat trapping.
So when all is said and done, sure, that forest is back where it was with the same amount of carbon - but the permafrost it helped melt (with accompanying release of methane) is still melted.