3 ms·

I haven't read that we can't just recapture the carbon by re-planting a bazzilion trees. I'll do some googling now.

loeg 6y ago
The problem with trees-as-carbon capture is: 1. They are only a net store of carbon while they're alive. 2. Because of that, you need to dedicate land to carbon-capture forest, indefinitely. 3. Burning fossil fuels for energy releases more and more carbon into the atmosphere. Like, you get N tons of carbon captured out of a given land area. It's constant per area. So you would need to continually grow the amount of forested land just to follow the amount of carbon released by burning fossil fuels. But: land is finite. The actual worldwide trend has been to deforest land, either for lumber, or slash-and-burn for subsistence farming in poor countries, or just to allow for population growth, or the large land area needed for wind and solar farms. We don't have a huge surplus of not-yet-forest land — can't grow trees in deserts.
- Chris2048 6y ago
  > They are only a net store of carbon while they're alive. Is wood not a carbon store?
  - Dma54rhs 6y ago
    When or a tree dies, or burns, during the decomposition process it releases the carbon back to atmosphere. Maybe you could bury them somewhere where decomposition it's slower or more difficult but hard to imagine doing it at scale.
    - Chris2048 6y ago
      Surely lumber, treated cellulose, contains a high % of the original carbon content (minus water)?
      - loeg 6y ago
        Lumber isn't a permanent removal from the carbon cycle. Wooden structures have a shelf life, and eventually the wood decomposes and re-enters the carbon cycle. The only way to sequester carbon via lumber would be to bury it in a way that prevents decomposition. I don't think this is an especially efficient method of carbon capture.
        Chris2048 6y ago
        By the same measure, CO2 is not a permanent state either, but it's an issue because of the imbalance in dynamic processes - The carbon stored by lumber is the amount of lumber in the world minus decaying lumber.
        philipkglass 6y ago
        36 billion tons of CO2 came from industry and fossil fuel combustion in 2019. [1] CO2 is about 27% carbon by mass. Cellulose is about 44% carbon by mass [2]. That means about 22 billion tons of cellulose needed to offset one year's worth of CO2 emissions. In 2014, use of wood products in all notable categories combined was about 1.25 billion tons [3]. Including just sawnwood and wood paneling, it was 0.827 billion tons. Since there's no plausible way to use 2500% as much lumber for structural purposes as we do now, and just harvesting wood and leaving it outdoors will lead to decomposition on short (decades) time scales, people consider charring it and/or burying it underground. Just building more structures out of wood is barely going to put a dent in the problem. Likewise, dynamically shifting the equilibrium toward wood from CO2 doesn't help much if the wood persists for only decades. The time scale for CO2 to naturally return to its pre-industrial equilibrium is more like 100,000 years [4]. We need sequestration measures that prevent CO2 from returning to the atmosphere over longer time periods than wood takes to decay naturally. [1] https://www.statista.com/statistics/276629/global-co2-emissions/ https://www.statista.com/statistics/276629/global-co2-emissi... [2] https://en.wikipedia.org/wiki/Cellulose https://en.wikipedia.org/wiki/Cellulose [3] https://www.forest2market.com/blog/fao-report-highlights-resurgence-in-global-wood-production https://www.forest2market.com/blog/fao-report-highlights-res... [4] https://www.amazon.com/Long-Thaw-Changing-Climate-Princeton/dp/0691169063 https://www.amazon.com/Long-Thaw-Changing-Climate-Princeton/...
  - loeg 6y ago
    Only until it decomposes, which is usually relatively quickly after it dies.

loeg 6y ago

The problem with trees-as-carbon capture is: 1. They are only a net store of carbon while they're alive. 2. Because of that, you need to dedicate land to carbon-capture forest, indefinitely. 3. Burning fossil fuels for energy releases more and more carbon into the atmosphere. Like, you get N tons of carbon captured out of a given land area. It's constant per area. So you would need to continually grow the amount of forested land just to follow the amount of carbon released by burning fossil fuels. But: land is finite. The actual worldwide trend has been to deforest land, either for lumber, or slash-and-burn for subsistence farming in poor countries, or just to allow for population growth, or the large land area needed for wind and solar farms. We don't have a huge surplus of not-yet-forest land — can't grow trees in deserts.

Chris2048 6y ago
> They are only a net store of carbon while they're alive. Is wood not a carbon store?
- Dma54rhs 6y ago
  When or a tree dies, or burns, during the decomposition process it releases the carbon back to atmosphere. Maybe you could bury them somewhere where decomposition it's slower or more difficult but hard to imagine doing it at scale.
  - Chris2048 6y ago
    Surely lumber, treated cellulose, contains a high % of the original carbon content (minus water)?
    - loeg 6y ago
      Lumber isn't a permanent removal from the carbon cycle. Wooden structures have a shelf life, and eventually the wood decomposes and re-enters the carbon cycle. The only way to sequester carbon via lumber would be to bury it in a way that prevents decomposition. I don't think this is an especially efficient method of carbon capture.
      - Chris2048 6y ago
        By the same measure, CO2 is not a permanent state either, but it's an issue because of the imbalance in dynamic processes - The carbon stored by lumber is the amount of lumber in the world minus decaying lumber.
        philipkglass 6y ago
        36 billion tons of CO2 came from industry and fossil fuel combustion in 2019. [1] CO2 is about 27% carbon by mass. Cellulose is about 44% carbon by mass [2]. That means about 22 billion tons of cellulose needed to offset one year's worth of CO2 emissions. In 2014, use of wood products in all notable categories combined was about 1.25 billion tons [3]. Including just sawnwood and wood paneling, it was 0.827 billion tons. Since there's no plausible way to use 2500% as much lumber for structural purposes as we do now, and just harvesting wood and leaving it outdoors will lead to decomposition on short (decades) time scales, people consider charring it and/or burying it underground. Just building more structures out of wood is barely going to put a dent in the problem. Likewise, dynamically shifting the equilibrium toward wood from CO2 doesn't help much if the wood persists for only decades. The time scale for CO2 to naturally return to its pre-industrial equilibrium is more like 100,000 years [4]. We need sequestration measures that prevent CO2 from returning to the atmosphere over longer time periods than wood takes to decay naturally. [1] https://www.statista.com/statistics/276629/global-co2-emissions/ https://www.statista.com/statistics/276629/global-co2-emissi... [2] https://en.wikipedia.org/wiki/Cellulose https://en.wikipedia.org/wiki/Cellulose [3] https://www.forest2market.com/blog/fao-report-highlights-resurgence-in-global-wood-production https://www.forest2market.com/blog/fao-report-highlights-res... [4] https://www.amazon.com/Long-Thaw-Changing-Climate-Princeton/dp/0691169063 https://www.amazon.com/Long-Thaw-Changing-Climate-Princeton/...
- loeg 6y ago
  Only until it decomposes, which is usually relatively quickly after it dies.