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Restoring natural forests is the best way to remove atmospheric carbon (nature.com)
173 points by pseudolus on April 2, 2019 | hide | past | favorite | 95 comments



When I was a kid, being an environmentalist was all about saving the rain forest. A century ago, it was all about the conservation of natural spaces. Today, it is all about carbon. To me, the carbon argument is shame-oriented while preserving (and cultivating) forests is value-oriented. This study calls into question the rhetoric of carbon -- if "restoring nature" is both necessary and more compelling for the general public. Carbon is abstract and removed. Natural forests have inherent, relatable value.


This article is about removing carbon, i.e. mitigating some of the damage that has already been done. We still have to stop actively doing more damage by continuing to burn fossil fuels.


Exactly! Not to mention that reversing desertification and deforestation need to be done anyway. The Amazon rainforest is producing 20% of the world’s oxygen. Why not focus on that, Bolsonaro? But how can we get the world to change its focus?

This is the biggest contributor to CO2 pollution:

https://www.nationalgeographic.com/environment/global-warmin...


Hm, I'd heard the Amazon consumes at least as much O2 as it produces; it's basically in equilibrium. Unfortunately I don't remember the source but it was something like Planet Earth.

I found a lot of sources quoting your 20% number, but it seems like that's not net produced O2 but rather gross.

I'd be interested if anyone can find a source that says either way about the net O2/CO2 of the Amazon.


With absolutely no expertise in the subject, I would expect any sufficiently large land area to have no net oxygen production. It's not like oxygen levels fluctuate wildly, and it seems unlikely to have such a uniform O2 level on Earth if it's coming from just a few big producers.


Basic chemistry: the only ecosystems that can continually produce net O2 are those that permanently stash unoxidated C away (aka new fuel). This was the norm A Very Long Time Ago when plants were briefly ahead in the chemical arms race against everything that lives off decaying plant matter (and thus caused an imbalance which created the chemical energy we now use as fossil fuels). But in more recent history (e.g. anything dinosaur or younger) it only happens in very rare conditions. Peat-producing bog marshes are the rare exception now.


Plankton dying and falling to the bottom of the ocean probably sequesters something like .005% of atmospheric carbon a year. That was the main way carbon got yanked out of the atmosphere in the past. The problem is that the process is slooooooooow. Way too slow to keep up with our output.


What about the other way, producing CO2?


When the ecosystem is somehow tapping into an ancient stockpile of high energy C compounds to oxidate, sure, it will release more CO2 than it consumes. An example of such an ecosystem would be humans doing agriculture boosted with the Haber-Bosch process, which oxidates fossil fuel to capture plant nutrients from the air (even our crops are not entirely solar powered).

Chemistry is incredibly simple when you are only interested in the general inputs and outputs of a black box system.


You are right, it does not produce more O2 than it consumes. Burning the forest is by far Brazil's greatest source of CO2. The forest also regulates the release of water to the atmosphere. It release as much water "transpiring" as the Amazon River estuary.

And the burning of the forest is increasing a lot in Bolsonaro's government. Well, it is increasing a lot since the president DiLma was ousted.


I believe the show "One Strange Rock" on Netflix mentioned this.


Every time an article on this topic comes up, I read the same responses in the comments, here or on Reddit.

Yes, it's cheaper not to emit than it is to reclaim, but how does this comment contribute to the solution? Even if everybody stopped emitting CO2 today, we still need to remove many Gigatons of CO2 from the atmosphere to save the planet. Planting trees is cheap and is PART of the solution.

Similarly, every time an article about direct air capture (DAC) comes up, somebody complains that we should be planting trees instead. This is ALSO a very unhelpful comment, because in truth we need to be doing both DAC and planting trees. Even if we reforested all the depleted forests of the world, there would still be gigatons of CO2 to remove.

The answer to every proposed solution to climate change is not whether "this or that", it is "this AND that". We need to be doing everything: reforest, DAC, wind, solar, nuclear, synthetic meats, etc. The whole kit.


Not to mention each solution has other benefits. Expanding swampland is a carbon sink and helps absorb storms & floodwaters. DAC is a carbon sink and paves the way to ultrapure synthetic designer fuel. Wind & solar save emissions, and improve air quality near human habitation. On and on. As far as I see it, they are all virtuous technologies, and their relationship with carbon is just one more reason.


Actually, it's possible to remove all the extra CO2 just by planting trees (not to detract from all the other things we should be doing).

Furthermore, it's affordable: $15/average US resident/year. I wrote a blog post about it recently:

https://automicrofarm.com/blog/2019/03/solving-climate-chang...


So, to offset his carbon emissions, American must plant 150 trees a year, ensure that they grow for at least 10 years, and then ensure that the CO2 captured by them doesn’t get rereleased. This means that we need space for at least 3 trillion trees, which is three times the space available, based on the figure in your link. Ensuring that the CO2 doesn’t get rereleased means that all that lumber needs to be buried or sunk, since this is way more lumber than the humanity actually uses productively. Additionally, this would mean doing heavy industrial management of all this immense forest area to cut and bury all these hundreds of billions of trees a year. This would require digging huge pits, transporting lots of heavy material to them, at extra emissions. And that’s for American emission only, which are only a fraction of global emissions. And of course we ignore the question why would you want to bury all this wood while keeping digging out all the fossils, when you could be using the same wood to generate energy instead.

So no, while this might work to pacify the conscience of an individual, it makes absolutely no sense to do it at scale.


Actually, if the trees are burned or otherwise re-release their carbon, the subsequent re-planting will take care of re-re-capturing that carbon. If any of the trees die or are cut down, a new one can be planted in its place. If it still living and thriving, it should be naturally left alone.

Also, for ten years, 327 million Americans each planting 1.5k trees comes out to half a trillion trees. The link in my blog says there is room for 1.2 trillion trees to be planted, so the math works out.


When the trees die, won't the carbon be re-introduced to the atmosphere over time via microbial decomposition of the wood? That is, once the microbes that eat the trees die, they'll be eaten by something that is eventually eaten by something on the surface, thus releasing the carbon sequestered by the tree.


How about we turn them into houses or furniture. Timber used in construction can last for a very long time, all the while keeping it's carbon locked up.

Even when it finally decomposes through rot or consumption a lot of the carbon is kept out of the atmosphere, ending up in the food chain fed by the organisms that consume it.

Plant a tree now, in 200 years it may be part of your great great great grandchildren.


Even when it finally decomposes through rot or consumption a lot of the carbon is kept out of the atmosphere, ending up in the food chain fed by the organisms that consume it.

No, not a lot. In fact, it’s practically nothing, compared to the mass of trees. Think about it: are you using the mass of 150 adult trees annually for buildings? Are you sequestering much of it in your body? Not even close. Today America consumes less than a half of a single adult tree per capita per year.

The carbon is only sequestered when the trees are alive or when they are buried or sunk. If you don’t bury and only have space for a decade of tree planting, you are at best going to delay the climate change by a decade, which is not nothing, but won’t change much. And, of course, we ignore things like albedo changes due to more forestation which could offset a big part of gain.


Yes, that could happen. Replacing the dead tree with a seedling will re-capture that carbon and return to a net-zero atmospheric carbon balance.

Also, there are many situations where a net-negative amount of carbon could be released into the atmosphere: the tree could be used as lumber to build something, thus not decomposing. Or it could be partially or fully buried, sequestering some or most of the carbon in the soil.


Using it as lumber will only extend the time period when the carbon is sequestered, but won’t sequester it permanently. You need to bury it for that, and bury it deep enough so that it doesn’t decompose.

More importantly, the actual lumber consumption is trivial. America consumes half of a single tree per capita annually[1]. Even if you assume that this half of a single tree gets sequestered permanently (which is not realistic), that’s a far, far cry from 150 trees yearly.

Really, this is all so silly: if you can grow so much biomass to offset all carbon emissions, why wouldn’t you burn that biomass instead of burning fossils and burying the biomass? It makes no sense, like most of the feel-good green plans.

[1] - https://www.fs.usda.gov/treesearch/pubs/50895


Why are you fixated on permanently sequestering the carbon? As soon as a tree dies, all you need to do is replace it by replanting the tree. It doesn't matter if the tree's carbon is immediately released in the atmosphere (by burning) or it happens after hundreds of years. The new tree will re-sequester the dead tree's carbon.

Also, if a tree dies, it frees up space for another tree. So in effect, as long as you keep those 1.2T trees growing (and replace any dead ones promptly), you will keep that carbon sequestered.

> Really, this is all so silly... It makes no sense, like most of the feel-good green plans.

At this point, it seems like you're just dismissing the idea. Feel free to do so, but you haven't provided any reason why it won't work.


> Why are you fixated on permanently sequestering the carbon? As soon as a tree dies, all you need to do is replace it by replanting the tree.

This is true on average in otherwise equivalent conditions, sure.


> Why are you fixated on permanently sequestering the carbon? As soon as a tree dies, all you need to do is replace it by replanting the tree. It doesn't matter if the tree's carbon is immediately released in the atmosphere (by burning) or it happens after hundreds of years. The new tree will re-sequester the dead tree's carbon.

Because a solution that can only possibly delay the climate change by a decade or two with extreme change to global ecosystems by immense program of forestation is no solution at all. Seriously, what’s the point of doing this, if it require extreme global efforts, and will only make marginal difference? It is much more cost efficient to simply replace emissions with (also rather inefficient) solar and wind, not to mention nuclear power, instead of offsetting them by planting trees, which has no chance of having any effect other than delaying the climate change by a few decades theoretically, and a few years in practice.

The question rather is, why are you so hung up on the idea of planting trees, if it’s not going to make any difference?

> Also, if a tree dies, it frees up space for another tree. So in effect, as long as you keep those 1.2T trees growing (and replace any dead ones promptly), you will keep that carbon sequestered.

Indeed, these 1.2T live trees will sequester the carbon. I do not question that. What I question is the point of doing that if you keep emitting carbon: this will only delay the climate change by a few years, because after you use up all available space and grow these 1.2T trees to maturity, you won’t be able to capture any extra carbon: all carbon captured by the trees will be offset by the carbon emitted by decaying dead trees (or huge forest fires, which are inevitable if you don’t remove fuel from these huge foerests), unless of course you bury them.

> Feel free to do so, but you haven't provided any reason why it won't work.

No, I did, you’re just ignoring it. Again, to recapitulate: planting trees will not offset carbon dioxide emissions unless you take on extreme effort to bury these immense amounts of lumber (which would also be stupid if you keep removing more fossils from the ground and burning them). Planting trees will only delay these emissions, by the length of time that is relatively trivial compared to extreme effort necessary, and insane amounts of ecosystems destroyed. Planting 1.2T trees would destroy so many ecosystems that it would be more ecological to simply do nothing.

Planting trees to offset carbon dioxide emissions from fossils is like putting a yoghurt cup under leaking drain pipe. It will work for a while, until the cup overflows, at which point you’re back to square one. You can then replace cup and pour out water in some other drain (that is, bury the lumber), but that’s stupid, because the whole point of a drain is to pour waste water into it, and if it is leaking, you should fix the leak instead of using some silly cup-to-other-drain scheme. Similarly, planting trees will only delay the inevitable, and when the cup overflows, that is, the tree dies, you need to figure out some other way to sequester the dead tree.


> Because a solution that can only possibly delay the climate change by a decade or two with extreme change to global ecosystems by immense program of forestation is no solution at all.

> Indeed, these 1.2T live trees will sequester the carbon. I do not question that.

It seems we agree that as long as these 1.2T trees are living (and any ones that die are replaced), the carbon will be sequestered. As long as humanity can keep on doing that, the delay will be... indefinite. Are we in agreement on that point?

With the leaky pipe analogy, it seems you are worried we'll run out of room to put dead trees. Indeed, burying them is a great idea, and that can be combined with Hügelkultur technique to produce better growing conditions for other plants, including... more trees.

As far as some of the other concerns you raise: the Trees.org organization can have a tree planted for $0.10 (by people who are happy to plant it and take care of it). By that measure, it seems this method is the least expensive (if we judge effort by the amount it costs) and least extreme of all. Will Trees.org be able to scale to 1.2T trees? It's hard to say. They've planted 155M trees so far, so they need to scale by a factor of ~10000x. It will certainly be hard, but it seems to be possible: we have room for them in places where trees previously grew (see the link to the study where the 1.2T number comes from). Recently, India planted 50M trees in one day; a startup has a goal to plant 500B trees by 2050 (if they have two equally-capable competitors, the 1.2T quota can be met before then).

What ecosystems will be destroyed by planting trees? Currently deforested areas? That seems hard to believe.

I view any carbon sequestration efforts to be a partial stop-gap effort until the world becomes mostly electrified and using renewable/nuclear energy. I am for all kinds of carbon sequestration efforts, but as a consumer, I would like them to be relatively inexpensive, and not have an unknown side effect. Planting trees meet both these requirements.


> It seems we agree that as long as these 1.2T trees are living (and any ones that die are replaced), the carbon will be sequestered. As long as humanity can keep on doing that, the delay will be... indefinite. Are we in agreement on that point?

Yes, as long as there’s a cup under leaking pipe, the amount of leak equivalent to the volume of the cup is sequestered. When the cup is full and starts overflowing (I.e. your trees start to die) you have to figure out where to contain the overflow. If you do nothing, it will simply spill on the floor (I.e. dying trees will decompose), which puts you back on the square one.

> With the leaky pipe analogy, it seems you are worried we'll run out of room to put dead trees. Indeed, burying them is a great idea, and that can be combined with Hügelkultur technique to produce better growing conditions for other plants, including... more trees.

Somewhat, but not quite. The real concerns is that burying trees while you keep extracting fossils is absolutely bonkers idea.

Burying trees would make sense (though not necessarily be most cost effective way to do so) in the future world where we no longer extract fossils. Then, growing trees and burying them would (extremely slowly, and at a huge ecological cost) bring us back to previous CO2 level before industrial revolution. If you keep extracting coal from the ground, however, burying trees is insanely stupid and wasteful thing to do, because it would be offsetting the fossil emissions by literally putting the fossils back into the ground. Why go through all the motions with planting trillions of trees, if you could simply not extract the fossils in the first place?

> I view any carbon sequestration efforts to be a partial stop-gap effort until the world becomes mostly electrified and using renewable/nuclear energy.

Look, if you don’t bury trees, all you do is introduce slight delay in the system. If you want to use the trees as a stop gap, then it makes much more sense to use the trees as a biomass, that is, burn them instead. That way, you’ll actually in fact be carbon-neutral.


Not if a new starts growing in place of the old one. The carbon is sequestered in the mass of the living trees so that is what counts


There are twenty times that many people on Earth. You would have to compactify the wood for building materials, or something similar, to properly sequester. I suggest iron seeding the equatorial pacific as cheaper and more scalable.


Americans produce a disproportionate amount of CO2 due to their lifestyle. So you don't need to plant twenty times that amount of trees to sequester manmade CO2; only 2.4x.

Also, as long as you replace any trees that die with seedlings, you don't need to worry about what happens to the dead wood.

This method comes out to a cost of $6.70/ton sequestered. Other methods can cost many multiples of this amount. Do you have any estimates for iron seeding of the equatorial Pacific?


US emits only 15% of global carbon dioxide. If you plant 2.4x trees, you’ll only offset 40% of global emissions. For 2.4x to cover global emissions, global emissions would have to shrink by 60%. If US emissions were reduced by that much, it would put US emissions per capita below present day Belarus and Bulgaria.

> Also, as long as you replace any trees that die with seedlings, you don't need to worry about what happens to the dead wood.

You do, though. If the wood decomposes, all the CO2 is released back to atmosphere, which puts you back at square one.


> Actually, it's possible to remove all the extra CO2 just by planting trees

The linked, peer-reviewed paper in Nature says otherwise.

Perhaps you could review it and point out their mistake?


Here's a paper saying there is room for 1.2 trillion more trees to be planted: https://eurekalert.org/pub_releases/2019-02/ez-pcc021119.php

Perhaps you could track down the discrepancy in the statements?


Anyone heard about the sargassum catastrophe in the Caribbean? [1]

While I think it is terrible it might be an additional great sink for CO2.

[1] https://www.youtube.com/watch?v=_XD92EgWzZg


Is this true? This is something I question a lot. Intuition tells me that the greenhouse effect of CO2 and other gasses determines derivative of climate change, but its often presented like it sets the absolute average temperature.

That is, if we stopped producing CO2 completely back to pre-industrial levels (somehow), would we expect the globe to get warmer? Or are both statements true because excess CO2 naturally leaves the atmosphere into space + gets absorbed into the ocean?


Part of the problem with climate change is that some of the effects are self-sustaining. For example, snow and ice reflect light back into space. If the temperature increases then more of the ice melts, so more light is absorbed by the earth which raises the temperature.

Then even if you get rid of the carbon, the temperature stays higher because the ice is gone and is no longer reflecting light back into space. And the ice is from the last ice age, it doesn't just refreeze on its own -- especially now that the temperature is higher.

Meanwhile with higher temperatures there are more areas of drought, which means less vegetation grows there, which means those areas can absorb less carbon. And that too is sticky. If the temperature stays higher then there continue to be droughts and less vegetation.

What this means is that we need to stop emitting carbon ASAP, and then on top of that ultimately do something to reverse the effects and actively work to get the temperature back down to where it was, because it may not be able to fix itself.

We think of the Earth as a self-regulating system, but that isn't because it's stable, it's because it's adaptive. Earth's temperatures have been higher than this and still sustained life, but none of that life was humans, and the previous changes were accompanied by mass extinctions.


> Then even if you get rid of the carbon, the temperature stays higher because the ice is gone and is no longer reflecting light back into space. And the ice is from the last ice age, it doesn't just refreeze on its own -- especially now that the temperature is higher.

Check the historical data on CO₂ levels from antarctic ice. It correlates perfectly with the ice ages (we had samples of ~400K years covering 3 previous), and guess what, we are now on the brink of a next one.


Were on the brink of a next one, on the geological timescale. Before we started burning all this carbon and went hard the other way.


How does this square with the recent story about Canadian forests being carbon positive rather than negative?

https://www.cbc.ca/news/canada/calgary/canada-forests-carbon...


A great deal of our forests are not "natural forests" anymore, and are mono-cultures that may be even more susceptible to issues of climate change (forest fire, pine beetle, ...). Managed (young) forests also hold less carbon than mature forests.

What I've been hearing is that one of the problems with Canada's "managed" forests is the reduction (in BC, at least) of deciduous trees which apparently can act as firebreaks [1]. BC (and the pacific northwest in general) has seen a steady increase in the length and damage caused by the fire season. It is April and we are already battling large fires in the province.

[1] https://www.cbc.ca/news/canada/british-columbia/it-blows-my-...


You'd know if you had read the article you just posted.

""That's because trees don't just absorb carbon when they grow, they emit it when they die and decompose, or burn.

When you add up both the absorption and emission, Canada's forests haven't been a net carbon sink since 2001. Due largely to forest fires and insect infestations, the trees have actually added to our country's greenhouse gas emissions for each of the past 15 years on record.""

Also, something not mentioned in the article (but added by a botanist friend), conifers in general apparently produce much more volatile oils, so are more susceptible to flames/ignition/burning.


It's conifer's terpenes that cause the haze* in the great smoky mountains.

https://www.livescience.com/46958-trees-ozone-pollution-map....

(*not the same as smog, you need NOx emissions as well for that to form)


What about the Sahara? Is that too time / labor / cost intensive to adapt?

An aggressive reclamation project of desert could both work towards progress in carbon recapture and add valuable natural resources to poor countries.


https://en.m.wikipedia.org/wiki/Great_Green_Wall

https://en.m.wikipedia.org/wiki/Sahara_Forest_Project

Have you heard of the great green wall or the Sahara forest project?


The Sahara as a desert is very important for the global weather cycle, as the hot winds created there help irrigate places with rainfall. Any significant amount of forestation on natural desert biomes could threaten to upset that cycle and make the whole situation worse.


This video ("Can We Terraform the Sahara to Stop Climate Change?") examines how we might do just that. The conclusion is that it's technically possible (like many things), but the cost far outweighs the benefit. It also introduces new climate risks.

https://www.youtube.com/watch?v=lfo8XHGFAIQ


Adapt Sahara ? It grew by 10% during last century and we can't stop its expansion (thing dunes, tall herbs and things like that to stop it) so I am pretty sure teraforming it isn't an option we have.


Nature is wrong.

Accelerated weathering is our first best hope of lowering CO2 in the atmosphere.

Weathering is the conversion of carbonates and CO2 to form bicarbonates.

Grinding and aerosolizing limestone and other similar minerals hasn’t been tried very much.

Unlike with anything plant-based, once CO2 goes through this reaction, it stays.

In a few billion years, it’ll cause the extinction of life on Earth, but that’s a problem we can take our time to figure out.


I had never heard of this so I googled around a bit. Thanks for bringing it up. It looks like an interesting area of active research. Apparently one of the promising minerals for sequestration is olivine, which, by some galactic irony, is largely sourced in the oil-producing nation of Norway.


This sounds like the best kind of geoengineering, using safe appropriate technology.

http://www.geoengineering.ox.ac.uk/www.geoengineering.ox.ac....

If you really want to add high-tech, then use drones

https://www.fastcompany.com/40450262/these-tree-planting-dro...


Let's not forget the oceanic ecosystems they also remove co2, all 3 should be mentioned all the time.


Build buildings out of wood -> Plant more trees -> build more buildings out of wood -> plant more trees, etc. This can sequester a lot of carbon over time, especially if said wood buildings are in places trees can't easily grow.


Cutting down trees can cause a release of stored carbon dioxide.

Structures composed of wood do not remove carbon dioxide from the atmosphere.

When old trees are cu down they should be replaced with new ones


> Structures composed of wood do not remove carbon dioxide from the atmosphere.

Why not? Just some napkin math here but:

Say you have three 10K kg trees. Wood is ~50% carbon, so that means they collectively contain around 15K kg of carbon. Cut them down and turn them into framing lumber and build a house. You now have a house frame with roughly 15K kg of carbon.

Now plant 3 trees where the old ones were. Once grown you have now collectively sequestered 30K kg of carbon - half of it is in the trees themselves, half in the house.

Keep doing that. After a decade you now you have 1000 houses that have each sequestered 15K kg of carbon from the atmosphere, or 15M kg of carbon.


I think you might be holding a spherical cow.

Does your math include the carbon necessary to harvest, transport, cut the lumber? And to haul away the existing structure?


> Does your math include the carbon necessary to harvest, transport, cut the lumber? And to haul away the existing structure?

True. I don't know how many lbs of carbon it takes to cut down, transport, and harvest a tree. But I would hope less than 15,000 kg.

If the trade off isn't worth it, use electric machinery and transportation powered by nuclear plants.


A building comprised of wood does not continue to remove carbon - but if that tree continues to live it continues to remove carbon.


Yeah, but you can plant a new tree, which will sequester carbon at a much faster rate than the mature tree it replaced.


yeah....but you do not need to cut down a tree to plant a new one.


There is limited surface area on the earth where trees will grow. If you want to utilize that maximally to sequester carbon, then you need to cut down mostly grown trees (which have stopped sequestering carbon) to make room for new trees (which can sequester lots of carbon). Then, in order to prevent the carbon contained in the trees you cut down from re-entering the atmosphere, you need to use the wood in some way where it does not decompose or get burned (to build houses, basically).


> > Structures composed of wood do not remove carbon dioxide from the atmosphere. Why not?

> Why not?

On average, does wood in structures release carbon through decay, fire, etc., faster or slower than if the wood was left in a living tree? Intuitively, I don't see any reason to expect effective sequestration.

Your analysis seems to suppose that if wood was not used to make a structure, the trees would instantly release their carbon and not be replaced, rather than continuing to grow.


> On average, does wood in structures release carbon through decay, fire, etc., faster or slower than if the wood was left in a living tree?

Trees don't grow at the same rate forever. They sprout up quickly and rapidly sequester carbon until they reach maturity, at which point there are diminishing returns in terms of carbon sequestration.

Treated wood is much more resistant to decay and fire than untreated wood.

> Your analysis seems to suppose that if wood was not used to make a structure, the trees would instantly release their carbon and not be replaced, rather than continuing to grow.

No, I'm saying that a mature tree sequesters carbon much more slowly than growing trees. Think about it. It's the same for animals. Babies grow like crazy and gain mass at an amazing rate. Adults... don't. I've been 150 lbs for the past 10 years. My son, however, was 6 lbs 2 years ago, 20 lbs last year, and 40 lbs this year. That means his body is locking away 20 lbs worth of matter per year.

Take a mature tree, turn it in to a building. Grow another mature tree in its spot and you've now sequestered effectively twice as much as having never turned the tree into a building. That's what I'm suggesting.


> Take a mature tree, turn it in to a building. Grow another mature tree in its spot and you've now sequestered effectively twice as much as having never turned the tree into a building.

It takes several (in many cases 5+) decades for a tree to mature (in the sense of growth levelling off.) The average proportion of original wood building remaining after 50 years is, well, less than 100%.

Probably significantly, more than if the old tree died and fell, so you could have some net gain, but it's not going to be 100%. (And its going to be even less if you are clearing land for the building.)


This has been studied pretty extensively, for example: https://www.fs.usda.gov/treesearch/pubs/38598

Some key points are:

1. Forests reach their maximum level of carbon sequestration after around 70 years. After this point, they are no longer a net carbon sink.

2. If you periodically cut down the trees, turn the wood into long-lived products (like buildings), and then replant, you can sequester more carbon.

3. Exactly how much more depends on assumptions about the length of the useful life of a building and what is done with the wood after the building reaches the end of its useful life.

4. If you're looking at net carbon emissions, you also need to consider substitution -- by using wood in a building, you're decreasing the need for other building materials like concrete and steel, which emit a lot of CO2 in their production. They model various scenarios on the paper.


Why natural forests? Would it not be more effective to focus on the plants/trees that consume the most atmospheric carbon?

There are certainly ecological arguments for natural forests v. artificial carbon-sequestration-optimized forests, but if maximum carbon sequestration is the goal, then the rational answer is to focus on those plants which sequester relatively large amounts of carbon instead of waiting for maybe a natural forest of not-necessarily-optimal plants to maybe grow on its own.

Also, last I checked, algae is still Earth's primary oxygen producer (and therefore implicitly the primary atmospheric carbon scrubber).


The primary consideration is avoiding a monoculture.

If you sit down and study which types of plants sequester the most carbon, and plant a forest comprised entirely of that species, you run into a few problems:

First, parasites tend to be much worse. Whichever parasite prefers that particular type of plant will have an enormous food supply and a subsequent population explosion, with dire consequences for the entire forest. As the plants die, they will release the carbon they've stored.

Second, different plants prioritize pulling different resources out of the ground. There isn't a simple recipe of ax carbon dioxide, bx water, cx nitrogen, dx phosphorus etc = x kg carbon sequestered. Some species need more nitrogen, some need more phosphorus, some need more water etc. Different areas of the soil will have different concentrations of each resource the plants need. By having a diverse population, you will better utilize the soil's diverse resources.

https://phys.org/news/2018-10-species-rich-forests-carbon-mo... DOI: 10.1126/science.aat6405

In the study, the monocultures they studied included monocultures of bamboo and eucalyptus, which are extremely productive monocultures. These plots were still less productive than diverse forests.

You're correct about algae scrubbing carbon faster than forests, however algae to do not sequester appreciable amounts of carbon. It's released back into the environment nearly as quickly as it is removed. Trees, on the other hand, sequester lots of carbon in their trunks and root systems, so they are an important consideration with regards to anthropogenic climate change.


I mean, I said plants and trees, plural. By all means we should be picking multiple genera and species and cultivars thereof to provide some diversity.

Re: soil diversity, by all means pick plants/trees that are suited to that soil, as long as they are especially effective at trapping carbon.

Fair point about algae.


Besides climate change, we also have a huge problem with natural habitat and species destruction. Its really quite irrational to ignore the opportunity for combined solutions.

Its irrational to continue to neglect natural systems in a world where their capacities to sustain diversity have been overloaded by anthropological targets.


> The regular harvesting and clearing of plantations releases stored CO2 back into the atmosphere every 10–20 years. By contrast, natural forests continue to sequester carbon for many decades4.

I'm not sure I understand... To me, the only question is, how much CO2 we store per km2 (which might be a higher number for a natural forest). The plantation being cut down and then regrown has 0 net impact, just like trees dying and new trees growing in a forest. The plantation being cut down and not regrown has the same negative (+CO2) impact as the forest eventually being burned/cut down.


> The plantation being cut down and then regrown has 0 net impact, just like trees dying and new trees growing in a forest.

That's logically equivalent to saying your car won't run out of gas because on balance there's always exactly as much fuel going in as being burned. It's missing the point.

The issue here is that a farm "stores" very little carbon, as most of it gets re-released at the end of the season when the crops are harvested and decomposed in some way back into atmospheric carbon. A forest, on the other hand, continues growing for decades as a net carbon sink. All the carbon it absorbs stays in the forsest as biomass (and metabiomass stuff like peat and logs and soil).

A mature forest, effectively, has a much larger "tank" for the carbon that doesn't involve storing it in the atmosphere, where we don't want it. Farms don't.


Well, what if you cut it down, use it as a long term building material, and then regrow it?

Seems a lot like that would turn atmospheric carbon into a building material.


A lot of it is used to make paper which degrades relatively fast. That being said it's still renewable, fairly recycable, and provides packaging that actually degrades instead of clogging the ocean, so we don't really want to mess around with that side of the equation if we can help it


A lot of paper in the US ends up in landfills. Paper in a landfill is sequestered carbon, since it basically does not decompose once it’s buried.

So, if you subscribe to a dead-tree newspaper, it might be better for the atmosphere to throw away the paper instead of recycling it.


Indeed, logging is a measurable carbon sink. It's not a very good one though, as really we're harvesting about as many trees for lumber as we can turn into houses locally.


My understanding is that a lot of the carbon is still released as the sap is dried out and so on.


No, that's not happening. The carbon is by and large stored in the cellulose, hemicellulose and ligning of the wood.

That carbon will go back to co2 again if the wood rots or burns - but not when it dries.


Got any source on that? Carbon generally isn't released without burning or so I thought. Though, this article seems to suggest that composted wood releases it's carbon which is at odds with what I thought I knew.


Biological process are generally a slow controlled burn. Compost burns the carbon for the energy that creates, releasing CO2.


"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.


It’s more than that.

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.


The problem is- that in poor countries, forrest are chopped down faster then you can rebuilt them. So what you need is a mixture of reforrestation- the natural forrest in diffiult to reach regions. And "crop" forrest - aka bamboo in those regions that will get pillaged.


I think part of this, at least, it eating meat much more sparingly. From what I understand huge swaths of the Amazon are slashed and burned to make room for cattle which do the opposite of sequestering carbon by converting any it finds into methane (and meat).

So basically we need to eat less meat to give plants more room. And we will need lots of room since we need to not only sequester the carbon of the trees we've previously destroyed (assuming they were burned and not converted into buildings), but all the millions (billions?) (trillions?) of pounds of hydrocarbons we've pumped out of the ground.

To sequester that much carbon we need trillions of pounds more life on earth than we currently have which means we need to let the oceans fill up with carbon-based mass (algae, fish, etc), let the rain forests and other carbon-high forests grow to their geographic boundaries.

I don't think it's the silver bullet, but it's definitely a great start and technologically easier than turning CO2 into graphene or diamonds or whatever.


I think part of this, at least, it eating meat much more sparingly.

Eating less meat gets mentioned whenever a climate change debate appears here. Perhaps my own position as a meat eater makes react somewhat critically to this (when I was a vegetarian, I had trouble with my digestion that eating meat seemed to solve).

With that caveat, I should say that even if producing less meat was a good solution to climate change, individual abstention seems unlikely to be a path that's going to get us very far towards this change. One can see various social movements against a variety of products which don't by themselves prevent the production of these products. Whichever actions one might describe in a "ten things one can do to save the planet" list, those actions will done by a limited number of people, determined by sociological factors. Moreover, reduce the demand for X environmentally product from group Y and you decrease the price, stimulating demand from group Z.

More concretely, I have friends are homeless and nearly homeless. Eating less meat might be healthier and less environmentally destructive but these people aren't going to make that choice because their choices and values revolve around what lets them survive. And broadly, if producers of a product can't sell to one group, they can find another group.

My claim is that any shift in agricultural CO2 production is going to require regulation, whatever choices some consumers might make just won't change things and to various extents, acting as if these choices are a program does more harm than good.


In the US, beef production accounts for about 2.6% of GHG emissions. Most beef eaten in North America was raised there. If you are from these regions, reducing meat consumption won't help the Amazon or much else.

Note that the issues with clearing the forests of the Amazon for beef won't end if beef production is banned or whatever. Those people still need to do something, which is why forest clearing for soy production is on the rise.


Anybody here buying forest just to leave it to grow? It's not so expensive to buy a few dozen hectares, something I've been wanting to do for a while



We've been considering it, but taking a more active role in rehabbing it by planting trees me helping them grow. There's loooots of land around that was previously used for farming or forestry that's pretty cheap.


For tax reasons you'll probably want to find a nonprofit to do that on your behalf.


The momentum and concern over climate change in the last decade has caused many humans to lose sight of the fact that preservation of remaining natural habitat is the immediate and absolutely critical concern. Too many people nowadays equate conservation with more abstract schemes to control climate over longer time-scales and impersonal spatial scales. If we lose good quality remaining natural habitat we will have lost all of what is most important to conserve.


Before we worry about removing atmospheric carbon, the easiest and simplest thing we can do is to emit less of it.

It's cheaper to not emit 1T of CO2, then to pull 1T of CO2 out of the air.


Why not both?


Because emitting less is an order of magnitude cheaper then sequestration, and there's only so much economic/political capital that we can marshal for this problem.

Optimize the critical path. When your patient is bleeding from a severed arm, don't waste time with slapping a bandaid on their little toe.


This would be good advice if there were a unitary "we" who had already agreed to pursue the least-cost route to climate stabilization. But Californians can't force Wyomingites to cut their emissions, the EU can't force Americans to cut their emissions, and so on. Human emissions are going to continue beyond the point where feedback loops can be damped simply by cutting back on combustion. When the warning is "only 12 more years" to finish a decarbonization process that should have started 30 years ago, you know that the problem won't be solved optimally.

It's tragic that everyone is going to pay more because humans couldn't coordinate soon enough to just do the smart thing, but that's how it is. The IPCC is discussing negative emissions strategies not because they're cheaper than cutting emissions but because humans are not implementing deep emissions cuts fast enough.


It's a good point. The more you look into the immense challenges of capturing a significant amount of CO2 from the atmosphere, the easier reducing our CO2 output looks.

There's a lot of (relatively) low-hanging fruit, like making transport more efficient and eating less meat.


I agree with you - I think it's unappealing to many people who come up with outlandish solutions because simply using less resources is unprofitable.

You can't stop entropy - but you slow it down.




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