Restoring natural forests is the best way to remove atmospheric carbon

https://www.nature.com/articles/d41586-019-01026-8

by pseudolus • 7 years ago

173 95 7 years ago

tomp• 7 years ago

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• 7 years ago

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• 7 years ago

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

ajross2• 7 years ago

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.

tomatotomato372• 7 years ago

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

ajross2• 7 years ago

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.

rsync• 7 years ago

"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.

EGreg3• 7 years ago

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

AtlasBarfed• 7 years ago

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• 7 years ago

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?

johnchristopher• 7 years ago

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.

tomatotomato372• 7 years ago

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.

cpeterso• 7 years ago

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

vkou2• 7 years ago

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.

justinator• 7 years ago

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.

bg4• 7 years ago

Why not both?

vkou2• 7 years ago

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.

chimprich• 7 years ago

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.

umvi5• 7 years ago

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• 7 years ago

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.

cgh2• 7 years ago

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.

donatj• 7 years ago

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...

fao_• 7 years ago

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• 7 years ago

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)

bobbyT314• 7 years ago

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-...

mchannon• 7 years ago

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.

cgh2• 7 years ago

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.

dr_dshiv• 7 years ago

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.

EGreg3• 7 years ago

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...

seveneightn9ne• 7 years ago

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.

AnthonyMouse3• 7 years ago

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.

weepingprophet• 7 years ago

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.

baxtr• 7 years ago

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

ip26• 7 years ago

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.

b_tterc_p• 7 years ago

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?

AnthonyMouse3• 7 years ago

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.

ph0rque7• 7 years ago

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...

_rpd• 7 years ago

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?

xyzzyz6• 7 years ago

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.

lifehacked• 7 years ago

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

umvi5• 7 years ago

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.

jrace3• 7 years ago

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

SideburnsOfDoom• 7 years ago

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...

yellowapple2• 7 years ago

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• 7 years ago

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.

yellowapple2• 7 years ago

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.

strainer• 7 years ago

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.

dharma1• 7 years ago

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

Matticus_Rex• 7 years ago

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

0815test• 7 years ago

https://en.wikipedia.org/wiki/Conservation_easement are relevant.

Pfhreak2• 7 years ago

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.

Myrmornis• 7 years ago

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.

LifeLiverTransp• 7 years ago

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.

Restoring natural forests is the best way to remove atmospheric carbon

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