3 ms·
Yes, but forests capture carbon quickly until the average age of the trees starts increasing. So zero to 50 years is good, but after that things really slow do
by sliken 7y ago
Yes, but forests capture carbon quickly until the average age of the trees starts increasing. So zero to 50 years is good, but after that things really slow down. The amount of wood becomes relatively constant.
So slowly, very slowly leaves fall/get eaten by bugs, break down, and get absorbed by new trees. But there is a net gain, just a very slow one. Then things like continents collide, mountain ranges come and go, and significant biomass gets buried and under pressure and time turns into oil/gas.
So for scale we could cut down all trees and bury it and take 638 gigatonnes out of our ecosystem. Not sure of the average tree age, but assuming it was replanted we could likely repeat that every 20-30 years.
The annual oil consumption looks to be around 36 billion barrels. Each weighs around 300 pounds. If my conversion is right that's about 4.9 Gigatonne.
So burying all trees every 30 years would be about 21.2 gigatonne a year or enough to offset all oil consumption AND decrease our current levels to pre-industrial levels.
Or we could just use less oil.
- nullc 7y agoConsider the scale of what you're describing now: cutting down and burying all trees on earth every 30 years. We could certainly _burn_ all of them every 30 years, but that wouldn't help. The figure you need is the marginal capture after the emissions from the process. Wikipedia says our current emissions from fossil fules and cement production is estimated at 10GtC (not absurd compared to your numbers, since you count only crude oil). So restating, if somehow without adding any new carbon buried _all_ the vegetation on earth every 30 years, we'd remove 21 GtC per year or a net reduction of 11. To get back to pre-industrial levels it would still take 34 years even ignoring the >1000 GtC currently in the ocean surface that would come out of solution and fight the reduction. (I have no idea how to setup the diff eqs for solving for the ocean contributions...) The fact that an emission free removal and replacement of all vegetation of earth would still take a long time is basically my point around "planting trees" not being a sufficient plan. :) Not that planting trees is bad, but solving this is going to take some mixture of reduction and magic (presumably both the political and technological kind).
- sliken 7y agoHeh, well I just wanted an idea on scale. It doesn't take millions of years, but less than 100. Certainly it wouldn't likely be 100% every 30 years, but 3.3% every year. As far as geo-engineering significant climate change this looks like one of the easier approaches actually. Of course it's much more feasible with the continued migration towards solar, wind, hydro, and related. Sadly I think Nuclear got the short end of the stick for mostly political reasons. Things like putting a nuke plant in a known tsunami zone, without protection, because of political lobbying. So all in all, agreed.
- tren 7y agoI'm wondering if the CO2 stored could be optimised through coppicing. Historically this technique was used to maximise the amount of wood for shipbuilding.