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That only "fixes" climate change as long as the trees continue growing and do not die. When dead, trees release their CO_2 that they've sequestered back into th

That only "fixes" climate change as long as the trees continue growing and do not die. When dead, trees release their CO_2 that they've sequestered back into the atmosphere due to decomposition. Therefore, assuming those forests stay around, you've only delayed the problem by sinking a fixed amount of CO_2 away into the living biomass of the trees. The only way to make that a permanent sink would be to biochar the trees as soon as they die, which would be a logistical nightmare. Negative rant over, it's still not a bad idea for the fact that it'd slow down the worst effects of climate change for a while, buying time for other solutions like renewable energy and whatnot, but it's not a pancea.

Ndymium 7y ago
But when the trees die, new trees will grow in the same area, sequestering more or less that CO2 that was emitted from the dying tree, no? Would this not turn the forests into a permanent CO2 sink, at least on a rough scale? Or do they sequester less than they emit?
- praptak 7y ago
  Once the forest grows to maximum height and density, it stops being a sink. It keeps being a storage though, which is still a benefit.
- ulrikrasmussen 7y ago
  I unfortunately can't find a reference, but I heard that it takes about 20 years for a newly planted tree to peak with regards to absorption of carbon, and after about 100 years it reaches equilibrium where the forest emits about the same amount of carbon to the atmosphere as it absorbs (through decaying matter, fallen trees, and whatnot). It of course depends on the type of tree.
  - praptak 7y ago
    I think it's best to look at this as mass preservation problem. Trees absorb CO2 from air and store in their bodies. Once they die, the CO2 gets released. Since there's a limited tree mass per area unit that the ground can support, once you reach that mass the input and output need to zero out, since there's nowhere to store any additional CO2.
  - llebttam 7y ago
    I'm not an expert in this area, but from what I can tell: Young rapidly growing forests sequester carbon more quickly than mature forests, but mature forests still sequester some carbon, possibly into the soil. (One source https://www.sciencedaily.com/releases/2008/09/080910133934.htm https://www.sciencedaily.com/releases/2008/09/080910133934.h... ) Separately, the regrown forest could be maintained in a state of peak carbon sequestration by doing selective logging from time to time, and as a bonus it would be profitable to do so.
ainiriand 7y ago
Well, the main purpose would be to avoid tree death. And even natural death of trees can be allowed considering that an oak lives around 150 years. Regarding what you say about releasing the co2 they have stored, keep in mind that the tree is not a co2 sponge. It takes co2 and transforms a big chunk of it in other carbon-based components useful to the tree. I recommend this article that clears some ideas about trees and co2: https://medium.com/the-philipendium/trees-and-carbon-dioxide-what-is-the-truth-c7f8c9d12602 https://medium.com/the-philipendium/trees-and-carbon-dioxide... I have to agree with the posted article, even if it is mixing acres and square meters in the explanations.
- seren 7y ago
  A sequoia sempervirens lives 1,500 years. I am not deluding myself that we will mitigate climate change by covering Earth in sequoia, but still that gives some timescale on how long trees can live. If we could mitigate climate change for another 1,500 years we would probably have found some other mitigations by then.
  - SketchySeaBeast 7y ago
    I fully support any plan that ends in the forest moon of Endor. What are even the odds we'd have fossil fuels left to burn in 1,500 years? I feel like we can safely say we'd have reached peak oil by then.
    - ainiriand 7y ago
      Great comment and even better concept.
    - natch 7y ago
      I don't know the source other than Elon Musk stated it in one of his presentations, but according to him we have five times as much fossil fuel reserves as we would need to utterly destroy ourselves with climate change. If that's right, waiting until we run out is not a solution. I realize the context was mentioning some speculation that we could push the timeline out some by planting trees. That speculation aside, we can't just wait for the oil to run out and be fine.
jacknews 7y ago
if you biochar fallen trees and litter, and then bury it, it stays sequestered for a long time. It also improves the soil long term - particularly in sandy soils it helps water retention. Obviously this is much more work that just planting and forgetting though.
- bergoid 7y ago
  > if you biochar fallen trees and litter, and then bury it, it stays sequestered for a long time. > It also improves the soil long term - particularly in sandy soils it helps water retention. > Obviously this is much more work that just planting and forgetting though. If we used cross-laminated timber [1] to construct our buildings instead of concrete, there would be an economical incentive to keep a lot of timber forests around. For additional carbon-negativity (and soil quality!) the timber industry could be required to biochar and bury its litter. This way, without too much government coercion, maybe our building frenzy [2] could end up being carbon negative? Much like modern diesel engines that make (polluted) air clean(er) [3]. [1] https://en.wikipedia.org/wiki/Cross-laminated_timber https://en.wikipedia.org/wiki/Cross-laminated_timber [2] https://www.youtube.com/watch?v=tXNJa86tErQ https://www.youtube.com/watch?v=tXNJa86tErQ [3] https://newmobility.news/2019/08/28/can-new-diesel-engines-actually-clean-the-city-air/ https://newmobility.news/2019/08/28/can-new-diesel-engines-a...
- te_chris 7y ago
  You don't need to biochar them, in a forest ecosystem they take care of themselves.
drderidder 7y ago
That's basically, well, not true. When trees break down they contribute to soil organic matter. Approx 58% of SOM is carbon (SOC) making soil one of the largest carbon sinks on the planet. See https://en.wikipedia.org/wiki/Soil_organic_matter https://en.wikipedia.org/wiki/Soil_organic_matter
- deleted 7y ago
  [deleted]
- triclops200 7y ago
  Does soil continue to break down over time or does it permanently sequester into peat/coal/oil? As far as I knew, basically all of the tree's cellulose eventually gets released over time into CO_2 via biological activity.
- pjkundert 7y ago
  If soil continues to accumulate in a healthy form, as it did on the Great Plains over millennia of grazing by bison herds, then yes. Old growth forests often grow on rocky land, and have little long-term depth accumulation. Source: hiking old growth forests over decades, and being a farmer.
  - hinkley 7y ago
    Literally survivor bias. The old growth forests that survived loggers were the ones they couldn’t get to for a profit. Those will be in or near geographic barriers like swamps or rocky terrain.
    - pjkundert 7y ago
      Hmmm? I've rarely hiked in harvested and replanted forests; these are boring. I did most of my hiking in central/northern BC and Alberta, Canada. These are some of the largest tracts of old-growth timber in the world. The many old-growth forests I've hiked (sample: >1,000km, mostly dominated by conifers), with last burn times ranging from decades to centuries, have rarely boasted deep soil levels. This hypothesis is supported by existing research: https://www.researchgate.net/publication/225314103_Soil_Carbon_Accumulation_in_Old-Growth_Forests https://www.researchgate.net/publication/225314103_Soil_Carb... Old-growth coniferous forests are great -- but they're not a big "carbon store". If you want land-use based carbon storage, I'd recommend investigating where the continent-wide, massive, deep, healthy carbon-rich store of topsoil and humous came from -- grazed grasslands and scrub brush.
izzydata 7y ago
We can continue to plant trees until the end of time.
- hossbeast 7y ago
  By end of time, I assume you mean entropic heat death of the universe. In which case no, planting trees will have become impossible trillions of human years previous to this, due to there not being and planets.
  - izzydata 7y ago
    I don't mean that. I mean something closer to the end of humans on earth.
alisson 7y ago
Some trees takes years to fully decompose, even in contact with the soy, even on tropical climate. I say because I practice a kind of agriculture where we plant trees to feed to soil, we prune/cut the trees to cover the soil 4 times a year, the soil keeps increasing in organic matter (becoming darker and darker each year) and I notice some especies are very good at not decomposing, usually this are trees used for civil construction, which is another way of storing the CO2 I think. For me cutting trees down is not the problem, the real problem is not planting more... also where that energy of the tree ends up, burning wood I think is a waste.
tafurnace 7y ago
I personally believe that forests provide a net positive in terms of CO2 scrubbing regardless of decay/decomposition. The only evidence I'd offer is a time lapsed NASA video[0] showing CO2 emissions heatmap over time. The areas like the Amazon clear up the CO2 on a daily and seasonal basis. The areas where forests are impossible like the Arctic, it does not. The sun drives the cyclical "heartbeat" effect you see from day to day on the video, where plants using photosynthesis in the day (and macroscopically, the summer) effects the intensity of scrubbing moreso. Also, maybe it is my mind's desire to simplify of all of it, but it was eye opening for me, and seemed obvious upon seeing that video, that forests were the key player in air management globally, and industrialized nations were the main drivers behind CO2 production in the air globally. [0]: https://m.youtube.com/watch?v=x1SgmFa0r04 https://m.youtube.com/watch?v=x1SgmFa0r04
marcyb5st 7y ago
I thought about this and had an idea that I don't know if it can work, but I couldn't find any major problem with it. Specifically, what if we start burying dead trees or those who reached peak mass in places where conditions will transform them into coal in 100(00..) of years? That way carbon is captured and stored until we burn them again.
- RockIslandLine 7y ago
  If deforestation is still occurring (net result that we are cutting down more trees than we are planting) then cutting down more trees doesn't solve the problem. We do in fact need people to just start planting trees.
  - marcyb5st 7y ago
    Of course. My point was to answer to the parent comment that said planting trees cannot be a long term solution.
- clort 7y ago
  I am not sure that coal can be made this way again. There are fungi and bacteria now which break down the lignin in cellulose, which there was not during the carboniferous period. That was 60 million years of dead trees not breaking down fully and being compacted underground to make that coal, and it won't happen next time because the lignin will be eaten.
falcolas 7y ago
Let's also not forget that forests burn. And they burn on a regular basis. You also run into tree-specific issues like beetles, which can kill off wide swaths of trees "naturally". So, natural death and decomp is not the only things to worry about with using forests.
agumonkey 7y ago
That's only one side of forest. Don't they contribute on thermal buffering, wind patterns and evaporation too ? Also it may help sustaining the good chain.

Ndymium 7y ago

But when the trees die, new trees will grow in the same area, sequestering more or less that CO2 that was emitted from the dying tree, no? Would this not turn the forests into a permanent CO2 sink, at least on a rough scale? Or do they sequester less than they emit?

praptak 7y ago
Once the forest grows to maximum height and density, it stops being a sink. It keeps being a storage though, which is still a benefit.
ulrikrasmussen 7y ago
I unfortunately can't find a reference, but I heard that it takes about 20 years for a newly planted tree to peak with regards to absorption of carbon, and after about 100 years it reaches equilibrium where the forest emits about the same amount of carbon to the atmosphere as it absorbs (through decaying matter, fallen trees, and whatnot). It of course depends on the type of tree.
- praptak 7y ago
  I think it's best to look at this as mass preservation problem. Trees absorb CO2 from air and store in their bodies. Once they die, the CO2 gets released. Since there's a limited tree mass per area unit that the ground can support, once you reach that mass the input and output need to zero out, since there's nowhere to store any additional CO2.
- llebttam 7y ago
  I'm not an expert in this area, but from what I can tell: Young rapidly growing forests sequester carbon more quickly than mature forests, but mature forests still sequester some carbon, possibly into the soil. (One source https://www.sciencedaily.com/releases/2008/09/080910133934.htm https://www.sciencedaily.com/releases/2008/09/080910133934.h... ) Separately, the regrown forest could be maintained in a state of peak carbon sequestration by doing selective logging from time to time, and as a bonus it would be profitable to do so.

ainiriand 7y ago

Well, the main purpose would be to avoid tree death. And even natural death of trees can be allowed considering that an oak lives around 150 years. Regarding what you say about releasing the co2 they have stored, keep in mind that the tree is not a co2 sponge. It takes co2 and transforms a big chunk of it in other carbon-based components useful to the tree. I recommend this article that clears some ideas about trees and co2: https://medium.com/the-philipendium/trees-and-carbon-dioxide-what-is-the-truth-c7f8c9d12602 https://medium.com/the-philipendium/trees-and-carbon-dioxide... I have to agree with the posted article, even if it is mixing acres and square meters in the explanations.

seren 7y ago
A sequoia sempervirens lives 1,500 years. I am not deluding myself that we will mitigate climate change by covering Earth in sequoia, but still that gives some timescale on how long trees can live. If we could mitigate climate change for another 1,500 years we would probably have found some other mitigations by then.
- SketchySeaBeast 7y ago
  I fully support any plan that ends in the forest moon of Endor. What are even the odds we'd have fossil fuels left to burn in 1,500 years? I feel like we can safely say we'd have reached peak oil by then.
  - ainiriand 7y ago
    Great comment and even better concept.
  - natch 7y ago
    I don't know the source other than Elon Musk stated it in one of his presentations, but according to him we have five times as much fossil fuel reserves as we would need to utterly destroy ourselves with climate change. If that's right, waiting until we run out is not a solution. I realize the context was mentioning some speculation that we could push the timeline out some by planting trees. That speculation aside, we can't just wait for the oil to run out and be fine.

jacknews 7y ago

if you biochar fallen trees and litter, and then bury it, it stays sequestered for a long time. It also improves the soil long term - particularly in sandy soils it helps water retention. Obviously this is much more work that just planting and forgetting though.

bergoid 7y ago
> if you biochar fallen trees and litter, and then bury it, it stays sequestered for a long time. > It also improves the soil long term - particularly in sandy soils it helps water retention. > Obviously this is much more work that just planting and forgetting though. If we used cross-laminated timber [1] to construct our buildings instead of concrete, there would be an economical incentive to keep a lot of timber forests around. For additional carbon-negativity (and soil quality!) the timber industry could be required to biochar and bury its litter. This way, without too much government coercion, maybe our building frenzy [2] could end up being carbon negative? Much like modern diesel engines that make (polluted) air clean(er) [3]. [1] https://en.wikipedia.org/wiki/Cross-laminated_timber https://en.wikipedia.org/wiki/Cross-laminated_timber [2] https://www.youtube.com/watch?v=tXNJa86tErQ https://www.youtube.com/watch?v=tXNJa86tErQ [3] https://newmobility.news/2019/08/28/can-new-diesel-engines-actually-clean-the-city-air/ https://newmobility.news/2019/08/28/can-new-diesel-engines-a...
te_chris 7y ago
You don't need to biochar them, in a forest ecosystem they take care of themselves.

drderidder 7y ago

That's basically, well, not true. When trees break down they contribute to soil organic matter. Approx 58% of SOM is carbon (SOC) making soil one of the largest carbon sinks on the planet. See https://en.wikipedia.org/wiki/Soil_organic_matter https://en.wikipedia.org/wiki/Soil_organic_matter

deleted 7y ago
[deleted]
triclops200 7y ago
Does soil continue to break down over time or does it permanently sequester into peat/coal/oil? As far as I knew, basically all of the tree's cellulose eventually gets released over time into CO_2 via biological activity.
pjkundert 7y ago
If soil continues to accumulate in a healthy form, as it did on the Great Plains over millennia of grazing by bison herds, then yes. Old growth forests often grow on rocky land, and have little long-term depth accumulation. Source: hiking old growth forests over decades, and being a farmer.
- hinkley 7y ago
  Literally survivor bias. The old growth forests that survived loggers were the ones they couldn’t get to for a profit. Those will be in or near geographic barriers like swamps or rocky terrain.
  - pjkundert 7y ago
    Hmmm? I've rarely hiked in harvested and replanted forests; these are boring. I did most of my hiking in central/northern BC and Alberta, Canada. These are some of the largest tracts of old-growth timber in the world. The many old-growth forests I've hiked (sample: >1,000km, mostly dominated by conifers), with last burn times ranging from decades to centuries, have rarely boasted deep soil levels. This hypothesis is supported by existing research: https://www.researchgate.net/publication/225314103_Soil_Carbon_Accumulation_in_Old-Growth_Forests https://www.researchgate.net/publication/225314103_Soil_Carb... Old-growth coniferous forests are great -- but they're not a big "carbon store". If you want land-use based carbon storage, I'd recommend investigating where the continent-wide, massive, deep, healthy carbon-rich store of topsoil and humous came from -- grazed grasslands and scrub brush.

izzydata 7y ago

We can continue to plant trees until the end of time.

hossbeast 7y ago
By end of time, I assume you mean entropic heat death of the universe. In which case no, planting trees will have become impossible trillions of human years previous to this, due to there not being and planets.
- izzydata 7y ago
  I don't mean that. I mean something closer to the end of humans on earth.

alisson 7y ago

Some trees takes years to fully decompose, even in contact with the soy, even on tropical climate. I say because I practice a kind of agriculture where we plant trees to feed to soil, we prune/cut the trees to cover the soil 4 times a year, the soil keeps increasing in organic matter (becoming darker and darker each year) and I notice some especies are very good at not decomposing, usually this are trees used for civil construction, which is another way of storing the CO2 I think. For me cutting trees down is not the problem, the real problem is not planting more... also where that energy of the tree ends up, burning wood I think is a waste.

tafurnace 7y ago

I personally believe that forests provide a net positive in terms of CO2 scrubbing regardless of decay/decomposition. The only evidence I'd offer is a time lapsed NASA video[0] showing CO2 emissions heatmap over time. The areas like the Amazon clear up the CO2 on a daily and seasonal basis. The areas where forests are impossible like the Arctic, it does not. The sun drives the cyclical "heartbeat" effect you see from day to day on the video, where plants using photosynthesis in the day (and macroscopically, the summer) effects the intensity of scrubbing moreso. Also, maybe it is my mind's desire to simplify of all of it, but it was eye opening for me, and seemed obvious upon seeing that video, that forests were the key player in air management globally, and industrialized nations were the main drivers behind CO2 production in the air globally. [0]: https://m.youtube.com/watch?v=x1SgmFa0r04 https://m.youtube.com/watch?v=x1SgmFa0r04

marcyb5st 7y ago

I thought about this and had an idea that I don't know if it can work, but I couldn't find any major problem with it. Specifically, what if we start burying dead trees or those who reached peak mass in places where conditions will transform them into coal in 100(00..) of years? That way carbon is captured and stored until we burn them again.

RockIslandLine 7y ago
If deforestation is still occurring (net result that we are cutting down more trees than we are planting) then cutting down more trees doesn't solve the problem. We do in fact need people to just start planting trees.
- marcyb5st 7y ago
  Of course. My point was to answer to the parent comment that said planting trees cannot be a long term solution.
clort 7y ago
I am not sure that coal can be made this way again. There are fungi and bacteria now which break down the lignin in cellulose, which there was not during the carboniferous period. That was 60 million years of dead trees not breaking down fully and being compacted underground to make that coal, and it won't happen next time because the lignin will be eaten.

falcolas 7y ago

Let's also not forget that forests burn. And they burn on a regular basis. You also run into tree-specific issues like beetles, which can kill off wide swaths of trees "naturally". So, natural death and decomp is not the only things to worry about with using forests.

agumonkey 7y ago

That's only one side of forest. Don't they contribute on thermal buffering, wind patterns and evaporation too ? Also it may help sustaining the good chain.