
Restoring natural forests is the best way to remove atmospheric carbon - pseudolus
https://www.nature.com/articles/d41586-019-01026-8
======
dr_dshiv
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.

~~~
EGreg
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...](https://www.nationalgeographic.com/environment/global-
warming/deforestation/)

~~~
seveneightn9ne
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.

~~~
dahfizz
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.

~~~
usrusr
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.

~~~
EGreg
What about the other way, producing CO2?

~~~
usrusr
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.

------
weepingprophet
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.

~~~
ph0rque
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...](https://automicrofarm.com/blog/2019/03/solving-climate-change-with-
trees.html)

~~~
xyzzyz
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.

~~~
ph0rque
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.

~~~
timClicks
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.

~~~
dragonsky67
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.

~~~
xyzzyz
_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.

------
donatj
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...](https://www.cbc.ca/news/canada/calgary/canada-forests-carbon-sink-
or-source-1.5011490)

~~~
fao_
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.

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

[https://www.livescience.com/46958-trees-ozone-pollution-
map....](https://www.livescience.com/46958-trees-ozone-pollution-map.html)

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

------
AtlasBarfed
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.

~~~
monetus
[https://en.m.wikipedia.org/wiki/Great_Green_Wall](https://en.m.wikipedia.org/wiki/Great_Green_Wall)

[https://en.m.wikipedia.org/wiki/Sahara_Forest_Project](https://en.m.wikipedia.org/wiki/Sahara_Forest_Project)

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

------
mchannon
_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.

~~~
cgh
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.

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

[http://www.geoengineering.ox.ac.uk/www.geoengineering.ox.ac....](http://www.geoengineering.ox.ac.uk/www.geoengineering.ox.ac.uk/what-
is-geoengineering/what-is-geoengineering/indexd41d.html)

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

[https://www.fastcompany.com/40450262/these-tree-planting-
dro...](https://www.fastcompany.com/40450262/these-tree-planting-drones-are-
about-to-fire-a-million-seeds-to-re-grow-a-forest)

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

~~~
umvi
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.

~~~
jrace
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

~~~
umvi
> 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.

~~~
dragonwriter
> > 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.

~~~
umvi
> 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.

~~~
dragonwriter
> 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.)

------
yellowapple
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).

~~~
nwallin
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...](https://phys.org/news/2018-10-species-rich-forests-carbon-
monocultures.html) 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.

~~~
yellowapple
I mean, I said plant _s_ and tree _s_ , 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.

------
tomp
> 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.

~~~
sambroner
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.

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

~~~
peteradio
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.

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

------
LifeLiverTransp
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.

------
umvi
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.

~~~
joe_the_user
_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.

------
dharma1
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

~~~
0815test
[https://en.wikipedia.org/wiki/Conservation_easement](https://en.wikipedia.org/wiki/Conservation_easement)
are relevant.

------
Myrmornis
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.

------
vkou
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.

~~~
bg4
Why not both?

~~~
vkou
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.

~~~
philipkglass
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.

