You can't plant a forest;* you can only plant a plantation.
May 29, 2020 12:48 AM   Subscribe

Planting Trees Won't Stop Climate Change - "Not only are planted trees not the carbon sinks you want, but tree planting frequently ends up doing more harm than good." (*The Forest Unseen)
posted by kliuless (33 comments total) 25 users marked this as a favorite
 
I can believe that the ecological impact of planting willy-nilly, especially importing foreign species or going monoculture in the industrialized way people are wont to do, might have serious downsides. But this:

A study led by the Lawrence Livermore National Laboratory concludes that any carbon sequestration benefit from trees planted much north of Florida is more than offset because solar heat absorbed and retained by the trees makes the climate warmer.

This doesn't sound right. It really does not seem likely trees are especially bad radiators given their shape. I would expect a patch of water would do considerably worse and also probably not absorb CO2 and produce O2.

I would also expect people at Lawrence Livermore know something about physics and what not, so I'm going to assume the journalism is the weak link here, but I'd be happy to accept pointers or counterpointers to understanding this.
posted by wildblueyonder at 1:38 AM on May 29 [14 favorites]


Yeah, doesn't the solar energy get absorbed by the trees and used, at least partially, by the chemical reaction that causes them to grow/sequester carbon? Leaves don't feel hot. Neighborhoods with trees are cooler. None of what I'm saying is science, but science is going to have to explain why I'm wrong.
posted by amtho at 1:44 AM on May 29 [8 favorites]


Yes, we have the same problem here with our "One Billion Trees", currently being majorly abused by commercial forestry companies.

A big issue is growing trees into soils which contain so-called recalcitrant carbon; millenia-old C forms in deep soils and where - as in the OP article - trees have never grown, or where the climate has moved on and trees are no longer the plant form for the place. Also there are many tree root morphologies and some trees may be suitable while others are not - e.g. shallow vs deep roots.

A good place to start is The Case for Digging Deeper: Soil Organic Carbon Storage, Dynamics, and Controls in Our Changing World. It's very readable and thoughtful:
"...the need to sample (often ignored) deeper soil layers. Contrary to long-held biases, deep SOC—which contains most of the global amount and is often hundreds to thousands of years old—is susceptible to decomposition on decadal timescales when the environmental conditions under which it accumulated change."

I told our Parliamentary Commissioner for the Environment about this but no one on his team had unearthed anything like it. I won't hold my breath for NZ to act on this though; What they seem to be doing here in NZ is avoiding anything which gives the little people and family farmers any agency, instead making sure that only corporates have this 'right'.

wildblueyonder, there is some odd heat effect driven by trees (if it's a thing I seriously doubt it would be all tree species), I've been reading about it this week but it's very counter-intuitive, alto' I thought it was only latent heat. I think it can be exploited to increase transpiration which is useful for planted stormwater systems.
posted by unearthed at 1:53 AM on May 29 [16 favorites]


Shame the shotgun title creates the usual pain of picking out the correct from the overblown... Planting trees alone most definitely cannot be the one-shot miracle solution, and it would be foolish to ever have thoughts so, so yes, all the commercial "solutions" and studies that would like to simplify the issue to that one technology, trees, need to be treated with utmost caution.

Yet, from the article itself:
"Planting trees can be beneficial, especially in countries where predatory logging and other land abuse has destroyed soil stability and deprived people of shade, clean water, fish, and fruit. But such initiatives are the exception."

And, from the qualified rebuttal to the recent Crowther Lab crowd-pleaser paper:
"In combination, our corrections for SOC and corrections to avoid the unintended consequences of misguided tree planting (i.e., warming and biodiversity loss with afforestation) would reduce Bastin et al.’s estimate of potential carbon sequestration by a factor of 5, to the still-substantial amount of ~42 GtC (Table 1). Although ecological restoration, if carefully implemented, can have a role in mitigating climate change, it is no substitute for the fact that most fossil fuel emissions will need to stop to meet the targets of the Paris Agreement (15). Such action should be accompanied by policies that prioritize the conservation of intact, biodiverse ecosystems, irrespective of whether they contain a lot of trees."

So: let's call out the offset scam, by all means. Would be great to do so without another Gibbs&Moore effect, though.

(What's the connection between the linked article and Haskell's book linked in the parentheses?)
posted by progosk at 1:56 AM on May 29 [8 favorites]


(What's the connection between the linked article and Haskell's book linked in the parentheses?) - oh wait, I understood the asterisk in the title now, ok.
posted by progosk at 2:03 AM on May 29


I live in a place that is naturally forested. Replanting our forests with native species is a net good, and it has helped reduce our urban heat island effect. Please note that unlike the Slate article, the EPA cites their sources there. I would love to see the "study led by the Lawrence Livermore National Laboratory" because it is contrary to everything I as an ecologist know about evapotranspiration, but I simply don't have enough information from the Slate article to actually track it down.

No, do not plant eucalyptus in California or blue spruce in Nebraska. Not a single ecologist is advocating for that. But by all means, if you live in a forested biome, plant your native species. Extensive research in applied carbon biogeochemistry at multiple free air carbon dioxide enrichment sites shows that trees in forested biomes do sequester carbon and will continue to do so as atmospheric carbon dioxide increases. Failing to emphasize that part, which we know works because we do have research that shows that it has worked, makes it look like this article is click bait that has selectively chosen examples that fit its thesis and disregarded the rest of the world.
posted by hydropsyche at 3:59 AM on May 29 [39 favorites]


A study led by the Lawrence Livermore National Laboratory concludes that any carbon sequestration benefit from trees planted much north of Florida is more than offset because solar heat absorbed and retained by the trees makes the climate warmer.

I think the reporter is referencing this research (sorry can't find the original, but this article sums it up). TLDR: Trees (particularly evergreens) are dark green in color which is darker than say....ice sheets, so they'll absorb more heat than an ice sheet therefore *hand waving, climate change, cut all the trees down*. The point of this research is to help climate modelers account for the many different factors that can impact climate change particularly as the tree line might move further north with a changing climate, not to encourage people to chop down trees.

I have many, many opinions on the use of this article (from 2007) completely out of context to make a dubious point. Why is it posted here?
posted by Toddles at 4:56 AM on May 29 [12 favorites]


You know, it's been awhile since I've seen a #slatepitch in the wild. The ecosystem must have changed on them, causing them to lose their niche.
posted by Huffy Puffy at 5:04 AM on May 29 [11 favorites]


I think the reporter is referencing this research (sorry can't find the original, but this article sums it up)

I believe it's this paper: Combined climate and carbon-cycle effects of large-scale deforestation
posted by progosk at 5:21 AM on May 29 [1 favorite]


I’d like to think this is more about bad reporting than bad science, but with federal agencies increasingly led by appointed saboteurs it’s tragically hard to say. The related work out of LLNL is generally strong.

This is not my main specialty but I have published a few papers on forests and carbon cycling, and I didn’t even finish reading bc of all the bullshit contortion necessary to make this sensational claim.

Slate is kind of shitty these days :-/
posted by SaltySalticid at 5:35 AM on May 29 [10 favorites]


If "any tree planted anywhere is good" is wrong, so is "any alteration of the natural landscape by humans is bad". We are part of the world and are just as natural as any native species, but people like the writer tut-tut at the slightest alteration of the landscape by humans. (Trees ruin the prairies? What about, you know, agriculture?) There are certainly better and worse ways of doing this, of course.
posted by Halloween Jack at 5:41 AM on May 29 [1 favorite]


I skimmed this article and must have missed the suggestions for what to do instead of planting trees.
posted by chavenet at 6:06 AM on May 29 [7 favorites]


Planting of non-native species is usually a bad idea (though I can think of exceptions, like the use of hybrid poplars for remediation of contaminated soils, or introducing more southern species in anticipation of climate change). And, planting trees in places that would not naturally have them seems like something to approach with caution.

But reforesting places that would have been naturally forested, using appropriate species and management tools, should be a clear ecological gain.
posted by Dip Flash at 6:25 AM on May 29 [3 favorites]


“Many of [Ireland’s planted trees] will be commercially valuable Sitka spruce from North America’s Pacific Northwest. When they’re harvested, sequestered carbon will spew back into the atmosphere.”

What??? Trees aren’t balloons and the Sitka spruce is valuable for its use as timber—so all the carbon that got sequestered into wood will simply stay put wherever we use the timber.
posted by Maecenas at 6:38 AM on May 29 [18 favorites]


I'm unhappy with this article, too, and I'm interested in what the author's agenda is - he's CEO of a fish rewilding association which seems to run in concert with fly-fishermen, and he blogs on a Nature blog about habitat restoration, but it all seems to be big projects. In particular, his bit on ranching felt pretty contemptuous of people who think the American West shouldn't be used for cattle grazing (I know next to nothing about it, myself).

Sitting here in southern England, it feels very different, because this is historically deciduous woodland, and every tree planting group talks about using local trees, and not planting too densely. Obviously they're not going to be making huge plantations because land's hugely expensive here, though - mainly it's about filling in the gaps around people's farmland and things like that. I know from listening to Irish media that the reforestation plan he mentioned in Ireland (with sitka spruce) was certainly not universally well received.

I'm much more optimistic with something like George Monbiot's rewilding agenda, which talks about general levels of management allow existing forest to spread (overgrazing by deer and sheep is a big issue here in northwest Europe), plus reintroduction of things like beavers. Finding ways to make this a positive and rewarding livelihood for the existing owners of the land is one of the most important starting points.
posted by ambrosen at 6:39 AM on May 29 [7 favorites]


Thanks to folks who managed to track down the referenced article. It is a modelling study. They did not model small scale deforestation or aforestation, but instead looked at what happened if entire latitudinal bands of forest were removed (something that thankfully has never happened).

Apparently, we can get substantial cooling through the albedo alteration that comes from deforesting the entire Earth, especially if we complete deforest the entirety of the boreal forest across North America, Europe, and Asia and replace it with grasses. This is despite the fact that "the removal of forests in the Global case results in an atmospheric CO2 concentration at year 2100 that is 381 ppmv greater than in the Standard simulation (1,113 vs. 732 ppmv)."

I had wondered about their negligence of the effect of evapotranspiration. This article seems to be partially a response to Bala et al. and seems to do a good job of pointing out the balance between the increase in albedo and the loss of evapotranspiration.

In other words, this has absolutely no bearing on whether local scale aforestation is a good idea or not. And even these folks in their thought experiment acknowledge "Although these results question the efficacy of mid- and high-latitude afforestation projects for climate mitigation, forests remain environmentally valuable resources for many reasons unrelated to climate."
posted by hydropsyche at 6:39 AM on May 29 [11 favorites]


... something like George Monbiot's rewilding agenda...

Yes. If we could just stop paying hill farmers to graze sheep in places that aren’t even economic, the forests would gradually return by themselves. You could call it ‘reversing the Highland clearances’.
posted by Segundus at 8:02 AM on May 29 [2 favorites]


A developer bought the 5 acres next door to my families property and decided to build a house. At first they were just going to clear enough land for the house. Then it was going to be half of it. Then the builder went to Mexico for vacation and left the feller in charge of the property. All 5 acres were sterilized up to the property line.

No point to this story other than I'm still processing all this and this article brought it back up to the surface. Sure, we could replant. But we lost all the other part of the forest: the fungus, plants, animals, bacteria, everything. The house that is built will require air conditioning because it will be baking in the sun all day. That should absolutely not have been necessary if not for the greed of the developer and feller.

Anyways, if anyone has a connection to someone in Western Washington who does native forest restoration, let me know.
posted by keep_evolving at 8:26 AM on May 29 [4 favorites]


Original clickbait headline and dek:
Planting Trees Won’t Stop Climate Change
Not only are planted trees not the carbon sinks you want, but tree planting frequently ends up doing more harm than good.
Accurate headline and dek:
Planting Trees without Ending Fossil Fuel Use Won’t Stop Climate Change
If you plant the wrong kind of trees in the wrong places, they can cause problems
But that's just common sense, so who would click on a link like that?

Anyway:

Plant trees
Not too much
Always native
posted by gwint at 8:47 AM on May 29 [37 favorites]


Sitting here in southern England, it feels very different, because this is historically deciduous woodland, and every tree planting group talks about using local trees, and not planting too densely. Obviously they're not going to be making huge plantations because land's hugely expensive here, though - mainly it's about filling in the gaps around people's farmland and things like that. I know from listening to Irish media that the reforestation plan he mentioned in Ireland (with sitka spruce) was certainly not universally well received.

Just how much of Western Europe was covered by forest vs meadowland is an open area of scientific debate and in any depends on when you go back to. There is a school of thought, led by Frans Vera that the presence of substantial numbers of large herbivores in the past would have meant a mixed terrain which was not all forested and that the idea of a squirrel being able to leap from the Urals to the North Sea without touching the ground might simply be wrong.

When we leave land alone now, after the removal of the large herbivores and their top predators, it almost universally turns to deciduous woodland (going through grass, to meadow, to scrub, to secondary forest, and eventually to old growth) but the question of whether the climax ecosystem is always wooded is open.
posted by atrazine at 8:48 AM on May 29 [5 favorites]


I skimmed this article and must have missed the suggestions for what to do instead of planting trees.

There is a brief mention of restoration of abandoned farm land by planting with native prairie grasses etc. This is a key issue. A lot of marginal farm land is abandoned as farm land without active measures made to revert to what used to be there. This usually means aggressive often invasive species take over instead.

Also it takes a long time to develop the kind of deep root system that some native grasses have. Shallower rooted grasses don't have the same ecosystem.

However it is also misleading to say "This is how it was in 1600 so that what we should return to." at least in North America when First Nations were also modifying the environment for agriculture and species management. Some places that were treeless prairie when Europeans showed up were only that way because First Nations had been setting fires to eliminate trees or provide grazing for bison for years. There has been a real back in forth in some places where first nations had cleared land; when they were killed off after first contact trees regrew; Europeans showed up and again cleared the land; that land became marginal for commercial exploitation and was abandoned; trees regrew; suburbs moved in and cut all the trees down; residents started planting trees for myriad reasons.

I believe similar things were happening in Australia pre-contact.
posted by Mitheral at 9:26 AM on May 29 [6 favorites]


All 5 acres were sterilized up to the property line.

Gah, I see this shit all the time in southern Washington. One dingbat with a giant truck and massive american flag pole just clearcut 3 acres of beautiful old growth forest by my family's old cabin. For what? So he could put in a large lawn. Seriously, the nerve of these pricks...
posted by Philipschall at 9:43 AM on May 29 [4 favorites]


We were up in Olympic National Park last summer and it was a real eye opener at how much logging still goes on right here in the US! Truck after truck of logs going by on the roads.
posted by Organic4ever at 9:48 AM on May 29 [1 favorite]


Apparently, we can get substantial cooling through the albedo alteration that comes from deforesting the entire Earth, especially if we complete deforest the entirety of the boreal forest across North America, Europe, and Asia and replace it with grasses.

Shit, just realized I misspoke here. The Bala et al. article advocates the complete deforestation of everything outside the tropics. Tropical forests are vital to the global carbon budget even under their model. Since tropical deforestation is happening faster than anywhere else in the world, this is a real concern.
posted by hydropsyche at 10:45 AM on May 29 [3 favorites]


I know it's probably confirmation bias but this kind of click bait is why I stopped paying attention to articles in Slate a few years ago.
posted by ElKevbo at 12:45 PM on May 29


I should have read the comments here first, it would have saved me time tracking down the Bala et al. PNAS paper myself. As a biologist-but-not-an-ecologist myself, I'm glad hydropsyche is weighing in, and would welcome corrections if I get anything wrong.

Although the PNAS paper only is referenced in a single line in the Slate article, this seems to be the only evidence cited in support of the idea that tree-planting actually doesn't work as a measure for climate change mitigation. The rest of the citations largely seem to deal with the idea that poorly-managed tree planting has negative effects on the local environment and ecosystem, which yeah, I think makes sense, but isn't really the same question as whether trees work for sequestering carbon into biomass during their lifetimes, and whether the net effect of this is global cooling. So since the title of the article is "Planting trees won't stop climate change" this is a pretty important piece of data being referenced, and it's interesting that it's one of the few (only?) that didn't actually get a link in the article.

And yeah, the paper doesn't quite seem to say what the author of the Slate piece says it says. Like hydropsyche said, Bala et al. modeled only what would happen under various scenarios of massive (total) deforestation. They find that tropical deforestation produces greater global warming, boreal deforestation produces less global warming, and temperate deforestation has essentially no effect on global warming. In their abstract and discussion, Bala et al. do draw an inference as to what that would mean for large-scale afforestation, or tree-planting, suggesting that tropical afforestation would be beneficial while boreal afforestation would be counter-productive with respect to global warming, but I don't think that inference is necessarily warranted. Total deforestation of the sort that they modeled is a pretty extreme treatment, and as we all know the climate is very complex: you can't just assume that because if you hit it with a sledge hammer in one way it flies off in one direction, that if you whack it with a mallet in the other way it will necessarily move the other direction. Their simulation is a really nice piece of work in showing how physical factors other than CO2 capture are significant, and may even dominate, when thinking about the net effect of forests on the climate, but it doesn't really demonstrate the thing they say it's demonstrating with respect to tree-planting. If I were a reviewer of this paper (which I wouldn't be, because it's not my field, but this sort of thing is basic scientific inference) I would not have let that pass: either they shouldn't have made claims about afforestation at all, or they should have run a simulation with afforestation to test their hypothesis.

But note also that the Slate piece describes this research with the following:
A study led by the Lawrence Livermore National Laboratory concludes that any carbon sequestration benefit from trees planted much north of Florida is more than offset because solar heat absorbed and retained by the trees makes the climate warmer.
This is inaccurate even if you accept the authors' interpretation of their simulation with respect to afforestation; you would need to replace Florida with Newfoundland or the English Channel for that to be correct. Between the latitudes of Florida and Newfoundland, they would say that the effects of deforestation (and thus they assume afforestation) are essentially neutral, not "more than offset." For the author of the Slate piece to say this is not just misleading, but wrong.
posted by biogeo at 12:50 PM on May 29 [7 favorites]


Leaves don't feel hot. Neighborhoods with trees are cooler. None of what I'm saying is science, but science is going to have to explain why I'm wrong.

This is a good question. I don't know what the actual numbers are regarding the magnitude of the various effects of trees and vegetation on local temperature, but you're right: neighborhoods with trees are cooler. However this isn't exactly the same thing as the local heating effects of albedo changes with increased tree cover, mainly because of the difference between surface temperature and atmospheric temperature. When you sit beneath a tree and it feels cool because you're in the shade, the heat is just being captured and moved around above ground level.

Leaves don't feel hot (though actually on a really sunny day, dark leaves can feel hot!) because they are good at dissipating heat in a few ways. They are good radiators because they have a high surface area to volume ratio, but I think radiative heat dissipation should move heat down to the ground as much as back up to the atmosphere. However they can also dissipate heat convectively, into the air around them, which will preferentially carry the heat upwards, away from the ground. And perhaps most importantly, they can dissipate heat evaporatively, which will also preferentially carry the heat upwards. So while the local effect of increased canopy cover can be a drop in surface temperature, this can occur even though there's a net increase in heat being absorbed and dissipated into the atmosphere. It's just that the extra heating is happening many meters above your head, so things feel nice and cool.

The other thing to consider with urban environments is what the alternative surfaces are that would be dominating the albedo. Light-colored concrete has a high albedo and might tend to reflect more heat than trees, but asphalt streets are very dark, and most roofing material is also dark. So in an urban environment the net effect of tree planting may be an increase in albedo even if the opposite is true in a prairie or other natural environment.

Not that I'm trying to defend the idea that tree-planting is actually a net negative for global warming: I don't know but I suspect it's not, and certainly this article was unconvincing. But there are a lot of complex factors at play, and our intuitions for how things work here on the terrestrial surface, at the bottom of the ocean of atmosphere that surrounds us, can lead us astray when we consider the big picture.
posted by biogeo at 1:13 PM on May 29 [3 favorites]


I skimmed this article and must have missed the suggestions for what to do instead of planting trees.

Well, yeah, but we know what the right answer there is. Stop burning fossil fuels.
posted by biogeo at 1:19 PM on May 29 [5 favorites]


With regard to this subject, a wonderful source of good information can be found in the books of a German forester, Peter Wohlleben
I had no idea how little we all know about trees.
posted by dustpuppy at 5:44 PM on May 29 [1 favorite]


Slate is a form of pollution unto its own.
posted by weed donkey at 5:59 PM on May 29 [1 favorite]


We were up in Olympic National Park last summer and it was a real eye opener at how much logging still goes on right here in the US! Truck after truck of logs going by on the roads.

I believe most of the logging in that area these days is coming off of state- (eg DNR) and privately-owned timber lands; the days of logging the crap out of the National Forest are mostly (though by no means entirely) past. A lot of it is high-impact logging of second-growth timber, and I've seen a lot of clear cuts closer to waterways than they are supposed to be. You can use the time-lapse feature in Google Earth to watch logging patterns over the years.
posted by Dip Flash at 8:26 PM on May 29


Planting trees that ultimately get burned somehow has very little benefit.

Planting trees that get buried, now that's a start.

Planting local trees that get buried and digested by local fauna/microbes... Perfect.
posted by rum-soaked space hobo at 4:03 PM on May 30 [2 favorites]


As a Permaculture trainee from way back, of course the answer is "of course we can plant forests".

Trees are most of the time better than no trees, regardless of climate change impacts, for thousands of other reasons.

Devil is in the details. . .
posted by goinWhereTheClimateSuitsMyClothes at 9:50 AM on May 31 [1 favorite]


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