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It doesn't look like they factored in the CO2 emissions from planting that many trees. The actual presentation: https://aaas.confex.com/aaas/2019/meetingapp.c

• m0zg 8y ago
  Nor the emissions when those trees burn because they were planted in a place where waterbed can't support their density. This is happening in CA nearly every year.
  • JumpCrisscross 8y ago
    > the emissions when those trees burn We'd probably have to sequester them somewhere anaerobic. Bottom of a deep-sea trench or underground. Which also reduces the net carbon footprint of the activity.
    • adrianN 8y ago
      The best way for sequestering wood is turning it into biochar. You even get some energy out of it.
      • TaylorAlexander 8y ago
        Doesn’t that release the captured carbon?
        • brohee 8y ago
          Not all of it, that's the point. Some pure carbon (charcoal) is left that makes good soil amendment. That carbon doesn't make it back to the atmosphere unless somehow burned.
          • TaylorAlexander 8y ago
            But the comment said we could get energy out. Wouldn't we burn it to get energy?
            • wackro 8y ago
              The creation of charcoal itself generates heat which can be used.
            • ncmncm 8y ago
              The wood has lots of hydrogen in it that is burned off, leaving most of the carbon.
    • chongli 8y ago
      Why not do something more useful and sequester the trees in buildings? Timber-framed houses for everyone!
      • kabdib 8y ago
        I wonder if the eventual fate of most lumber is to be burned, on the scale of tens of decades (as buildings deteriorate, are remodeled and older bits thrown out). In which case you're just postponing the need to sequester anyway.
        • chongli 8y ago
          It doesn't need to be sequestered eternally, it just needs to be captured and sequestered at a faster rate than it's being produced (from fossil fuels and decay/burning of wood). Where I live (Kitchener-Waterloo), there are a lot of old factories with heavy timber frames and solid hardwood floors. These factories have since been converted into nice condos and commercial properties, with all of that wood preserved intact. The old timber beams and hardwood floors are actually very nice now.
        • rebuilder 8y ago
          I think you have to consider what you're comparing against. Are we comparing to just not cutting trees down? Trees fall and decompose, while wood buildings can last for centuries. Admittedly building 300-year houses seems like a pretty different idea of construction than what we're doing now. So it comes down to how long you expect the building to last, but it's important to remember the carbon in trees will eventually be released into the atmosphere in any case. But! It's also important to consider what timber houses would replace - concrete. Concrete is not very climate friendly. Throwing that into the equation, I'd be surprised if wood construction wasn't better for the environment than what we're doing now.
    • WalterBright 8y ago
      Or use the wood in construction.
  • agumonkey 8y ago
    nor the small emission from natural decay of dead wood That said it could also: - absorb some heat - create new wind / rain cycles - provides a lot of material (construction/furniture) to replace cement and plastics - kill millions of people of exhaustion from planting that many trees
    • m0zg 8y ago
      Planting is something we know really well how to automate, though. Planting is the most tractable problem in this (hypothetical) solution. Also, more rain means more clouds, and this is something the current climate models can't really model accurately, believe it or not. There's not even "consensus" on whether clouds are beneficial or detrimental.
      • agumonkey 8y ago
        I can certainly understands we have modeling limits
    • frogpelt 8y ago
      If each person on the planet would plant 150 trees this year, we would be finished.
      • agumonkey 8y ago
        For some reason I pictured people moving fully grown trees .. planting 150 seeds is not a lot indeed.
  • jayd16 8y ago
    The burning an decay of a planted tree would at worst be carbon neutral.
    • avip 8y ago
      Which Carbon though. Trading CO2 for CH4, for example, would not serve us well.
    • asdfasgasdgasdg 8y ago
      Right, but if the point of planting the trees is carbon amelioration, than carbon neutral would somewhat defeat the point. I've seen this argument before, and I think the real place it falls down is that there just isn't that much space. For mature growth forest, you have something like 40-ish big hardwood trees per acre [1]. Those are, to my understanding, the only ones that are really relevant because they make up most of the biomass. Other types of trees are just a rounding error. `1.2e12 / 40 acres -> square miles` (frink) is 4.7e7 square miles. That is more than the whole land area of Earth [2]. There is certainly not enough land that would support mature forests available to plant so many trees, unless I have made a serious calculation error. [1]: http://www.sbcounty.gov/calmast/sbc/html/healthy_forest.asp http://www.sbcounty.gov/calmast/sbc/html/healthy_forest.asp [2]: https://hypertextbook.com/facts/2001/DanielChen.shtml https://hypertextbook.com/facts/2001/DanielChen.shtml
      • hannasanarion 8y ago
        That only holds true if you assume that every tree ever planted burns down within ten years. Many, possibly even most, of them will be harvested for wood, becoming a permanent carbon sink, or will be left alone to grow to maturity.
        • asdfasgasdgasdg 8y ago
          That in turn only works if you assume that wood never rots, burns, etc. I don't have any solid information on the annual growth in processed wood in existence, but I suspect that, to the extent it is increasing, this will gradually taper off as population growth slows. Now if you're saying we could bury the wood somewhere where it won't rot, well enough. That does seem feasible. But normally when I read stuff like this, people think just planting and leaving the trees will be sufficient. And it won't. At any rate, if that's what the research is getting at, they probably need to title it differently, or explain early on that merely planting the trees is a necessary but not sufficient condition to achieve the wins they envision.
• strainer 8y ago
  You have wildly mistaken the plain meaning of that statement. They declare their model suggests global warming will drive the loss of carbon from soils - not Trees, or aforestation programs.
• wolfspider 8y ago
  That’s a really good point also where water and irrigation is concerned hopefully that would be done in the most sustainable way possible. The idea of “offsets” unfortunately has been given a bad name politically due to unscrupulous actors. Really it could work if the public oversight was there in real time and all the facts on the table. Still, we are living in an age where efforts done “in everyone’s best interest” are a hard sell. We wouldn’t even be here if it weren’t easier to sell a pair of new shoes than clean air and water.
  • reaperducer 8y ago
    That’s a really good point also where water and irrigation is concerned hopefully that would be done in the most sustainable way possible. I wonder how many of those 1.2T trees could be accomplished without starting huge new forests or in places that require irrigation. There are cities in places with ample rain that already have 1,000's of vacant lots. Ten trees per vacant lot could start to make a big difference, if only regionally. Maybe Americans should stop thinking of Arbor Day and the Arbor Day Foundation as quaint square leftovers from a past generation, and start thinking of them as a framework to save the planet. https://www.arborday.org https://www.arborday.org I'd welcome two new trees in my front yard and two in the back, but my HOA won't allow it. I've already reached my maximum vegetation allowance.