This is the "Yes But!!!" Issue. Cutting forests and trees for construction may help the building industry but long term it is not great for biodiversity that supports other key life processes on our Earth ship. Mono-culture of fast growing trees is generally a dead zone for critters and other plant diversity. The conundrum is to stop massive climate change but also continue supporting/protecting critical biodiversity. E.g., One could give massive amounts of NSAIDs to curb a high fever to a patient , but if long term this is also is destroying their liver, digestive system etc. so they may die early in any case does it really help? A conservation ecologists $.02 (US) worth.
Great article Lloyd - and you're right it is a great and timely book. I agree a race to the tallest is counterintuitive - if the reason we are building in timber is about sustainability, why build a non-sustainable model. We need to be mindful of every planetary resource that we use and therefore contemporary design needs to prioritise sufficiency.. there are more than enough buildings to be built where timber should be used and carbon can be stored. Intensifying the use of timber in any one building as a carbon store is nonsensical. Touch the ground lightly .. not with 18m piles.
Growing willow for insulation sounds fine. But it only works if we are already using all the wood fiber left over from making lumber. We aren't doing that now. Timber HP is the only US manufacturer of wood fiber insulation. It processes a tiny fraction of the slash/chips left from lumber making. Planting willow for insulation only means more slash/ chips left to rot or burned to make heat or power.
Great to read your review, Lloyd. I was almost losing faith at certain points but relieved with your conclusion! 😅
Love the thoughts on insulation and agree fast growing crops like willow hold great promise. (Back to traditional approaches like coppicing,with some updating and new applications!)
I still don’t buy the substitution argument though, other than as a possibly useful emotive one to make a point. Getting to low/net-zero emissions is about the real emissions that occur not fictional emissions that might have happened but were avoided.
Yes but the emissions that count are those of the materials you actually use, not those you might have in a fictional scenario or a theoretical improvement.
If the building is going to get built, because there is a need for the space, then less carbon will have been generated by the lower-carbon materials than by the alternative higher-carbon materials.
My ingrained inclination is against one size fits all answers, we need a toolbox full of things but with a deeper understanding of the relative pros and cons of- the necessary trade offs between one solution or technology and another.
Robert, I agree, one size fits all answers rarely work. Hence I was careful with the title of the book ie 'Timber! How wood can HELP tackle climate breakdown', capitals added. I didn't say 'How wood can STOP climate breakdown'. Wood is not a silver bullet but it can play a significant role which amounts to at least 15 percent of the answer to climate breakdown.
Will ill-begotten euphemisms ever cease? I guess the reasoning must be "keep changing the words - we just might create a smidgeon of a passing flicker of interest in someone.
"showed a low rise apartment building built of Cross Laminated Timber (CLT), noting the wood in her company's Strandparken project was replaced by new growth in 44 seconds."
Are we REALLY supposed to blithely accept that "in 44 seconds" without hesitation. Thousands of board feet of wood used to erect an apartment building are replaced in less than a minute?
How many trees were harvested for that project and how long will it take for the replacement seedlings grow to the same level of maturity? C'mon, Lloyd...
Sorry Lloyd - after re-reading it 3 times, no mention is made concerning the 44 seconds. The only thing that comes close is the 602,280 seconds for growing a willow tree from a 30cm cutting.
Since there was not context applied with it, it's a real bad look for the quote/post - as if trees just spring up like Jack's Magic beans. And later in doing some other looking around, I saw some context elsewhere (have no idea if they are dodgy or not - I do think so) in that the reference MIGHT HAVE BEEN that it references ALL the remaining trees in the aggregate for that forest would replace the cut-down wood for the building.
I note that Lloyd didn't come in and rescue it when he said he challenged it and I didn't see the challenge in his post.
Words have meanings and they should be precise when used.
Oregon alone produces 3.8 billion board feet (whatever that is, why must you use such weird units)
Which equates too approx. 6,000,00 metric tons.
There are 31 million seconds in a year so that is 1 metric ton every 5 second.
so 10 tons is approx 44 seconds, but they were counting all USA not just Oregon.
I suspect that's how they did their maths approx.
Thats also about 1,600,000 of carbon. or 24,000 properties at 250 tons per property.
However not everything is good.
Industry emissions are approx 1,200,000,000. Of which about 15% is building or 108,000,000 tons (note numbers do not include power) so 1.487% reduction not counting the carbon emissions of providing all that wood.
So, in the grand scheme of things F**K All. (that's the technical term)
It would also of course need the doubling of the timber take.
Regarding insulation... what about Roxul & other stone derived insulation products? I had thought they had legitimately very low embodied GHG emissions, and would have much less land-use/biodiversity issues.
It is also worth noting that there are major advances in cement and steel industries that could get these industries to zero emissions. It'll be 3-4 decades best case before these industries are completely decarbonized globally. But much more sustainable alternatives will be available to progressive designers & developers in the next 5-10 years.
I remain unconvinced, notwithstanding Lloyd's swayed opinion. Appreciate the great overview of the book though, Lloyd!
Hi Brendan - Paul here, the author of Timber! As I point out in the chapter on insulation in the book Roxul Rockwool is in most cases a major climate problem. Essentially it is made by taking rock / stone and then melting it into a liquid before spinning the liquid - as if making candy floss - before cooling it and making sheets of insulation. The problem with this is a very high temperature is needed to melt the rock/stone and this, in most cases, is achieved by burning fossil fuels - de facto you have large CO2 emissions. You could use energy from nuclear power or hydro which would be green energy but this is rarely the case.
The key question with the manufacture of insulation is therefore how was the energy made to manufacture the insulation irrespective of what the insulation is actually made from. A wood fibre insulation made using a wet process might involve using a large amount of energy to then dry the product. Did this energy come from burning fossil fuels? If so, like the Rockwool made with fossil fuels, it will have a high level of embodied carbon.
The fact that stone is a natural material does not make its use in making insulation a good thing. Why not? Because stone is not sustainable ie you cannot simply 'grow' some more to replace what you have used. Essentially it is a finite material. Often stone quarries near large centres of population have become exhausted leaving a moonlike landscape devoid of biodiversity. It is the same with limestone quarries where the key material for making concrete is mined.
Returning to insulation - while Rockwool and wood fibre insulation may both have high levels of embodied carbon as a result of burning fossil fuels during their manufacture only one of them - the wood fibre - can store carbon that has been removed from the atmosphere = a good thing. Consequently the insulation that is better for the climate will be the wood fibre insulation and if it has been made with green energy then even better.
Do we have enough biomass (woody fibre) to make massive amounts of insulation? Yes, we could have is the short answer. The longer answer forms four chapters of the book!
Cement and steel are both decades away from anything other than a very small amount of both materials being produced with low levels of embodied carbon and where it does happen it will be expensive.
My understanding has been that rock wool insulation (like Roxul) have a carbon footprint today comparable to fibreglass batt insulation. See e.g. this article from Green Building Advisor - https://www.greenbuildingadvisor.com/article/does-your-insulation-have-low-embodied-carbon (This study is very friendly to bio-based insulation & other materials, BTW. As noted above & below, I question the logic that forest-based materials are "carbon negative"). As electricity & heat decarb, we can further decarb e.g. rock wool energy inputs - this is happening fast over next 1-3 decades.
I encourage anyone reading this to review the Energy Transition Commission's report
When we clear cut forests for wood, insulation, energy, etc. there are significant carbon cycle impacts. The forests that would have grown and absorbed more carbon are cut. Critically, soil carbon is emitted to the atmosphere in a large pulse due to the changes in local climate & hydrology. Jim Pojar (botanist & ecologist) does a good job explaining these dynamics for a fairly lay-audience - https://skeenawatershed.com/wp-content/uploads/2022/06/Pojar-ForestsAndCarboninBC-2019.pdf Forestry is not "climate neutral" as the industry has successfully led even thoughtful authors to believe.
Finally, Paul, respectfully, your argument that mining rock creates a "moonscape devoid of biodiversity" while we can "simply grow more [forests] to replace what we have used" is outrageous. It is a gross simplification of forests' value for biodiversity - young tree plantation style forests are often the ecological "moonscapes". And forestry takes so much more land to produce a given amount of material than mining rock. Take a Google maps tour of British Columbia's Chilcotin and Cariboo to see just how much land industrial logging impacts! And then check out some of the way that quarries have been restored to provide some biodiversity value and human amenity (I like this one - https://landscape.coac.net/en/node/8337). I'm not an apologist for mining/quarry's - they can devastate landscapes. But forestry can too, and on a much wider scale due to the inherent land-inefficiency of wood vs. stone.
Hi Bruce - as the author of Timber! I'd make the following points:
- if the priority is biodiversity, and only biodiversity, then humankind needs to depart the earth as our presence is without doubt a negative when it comes to biodiversity
- but that hopefully isn't going to happen
- as I point out in the book the global population is set to rise by an extra 2 billion by 2050 and they will all need somewhere to live
- as it stands most of them will live in mid-rise apartment blocks in an urban setting made from concrete & steel which together account for more than 12 per cent of global carbon emissions, that's more than the whole of Europe
- hence we need to switch to nature-based materials such as sustainable timber which can sequester CO2 when growing, substitute for more carbon intensive materials (the steel & concrete) and then also store carbon
- but yes, it has to be done sustainably and with due regard to biodiversity
- North America not my area of knowledge but here in the UK and Europe more widely we are improving in this area and aim to do better
- replanting felled trees with only one species is an increasingly bad approach given climate change much better to plant a mix, as we do in Europe, as this spreads the future risk
- clearly not all forests should be available for commercial timber production we also need large areas of protected woodland where biodiversity is the priority but don't fall into the mistake of thinking it's an either or - it can be both.
Lloyd, I'm not sure about some of the assumptions that the author appears to have made in this book, if I'm understanding his argument correctly. I haven't read it, so maybe these were explicit in the book, or maybe hidden; regardless, pro-CLT/mass-timber messaging is big in my region and touches on the work I do, so I am familiar with many of the common talking points. It seems that this whole idea of mass timber as a climate solution (through carbon sequestration) only works if a few things are true:
Assumption (1). Young trees sequester carbon at a faster rate than old trees of the same species. But the data doesn't support that: https://www.nature.com/articles/nature12914, one example of several I could link.
Assumption (2). The carbon remains sequestered in a structure for longer than it would remain sequestered in trees (which could be one very long-lived tree with a lifespan of several hundred years, like our conifers in the western US/Canada (or oaks anywhere), or naturally occurring generations of replacement trees). For the carbon-embodiment in construction studies I've seen, the lifespan of a typical American building before demolition is assumed at 30 years. See here, noting that several decades is the presumed max: https://www.pnas.org/doi/10.1073/pnas.1720064115. Could we do better? Sure. But will we really design our wood buildings to last several hundred years? (I doubt it, at least not in the US.)
Assumption (3). Tree plantations on a frequent harvest rotation provide comparable carbon/climate benefits to functional forest ecosystems. Multiple studies have shown this is not true, not to mention it's obvious when considering an appropriate analogy. Ask whether a cornfield provides the climate benefits of an intact prairie ecosystem, and of course the answer is a clear no. https://academiccommons.columbia.edu/doi/10.7916/kc4f-j904
The author's argument also seems to work only if the complete carbon lifecycle of harvesting and processing wood into wood products is elided, at least in part. In my state of Oregon, researchers have quantified all that data, and when you offset for all the diesel fuel for the logging equipment, all the soil carbon (and sheer biomass of plants and animals) that's degraded and lost when the forest floor is exposed to skidding and sunlight), fuel for transport to mills on semi trucks, wood volume lost on the sawmill floor, proportional sawmill emissions, waste wood landfilled/burned, and used wood likely landfilled at the end of the building's (short) lifespan, only some small portion of the carbon embodied in the tree makes it into a building.
There's more, like the fact that just looking at carbon emissions/sequestration ignores all the other ways that intact forests contribute to climate regulation besides mere carbon storage. If CLT/mass-timber is a reasonable path forward, great, but it comes across to me like a false solution, especially when its proponents push for increased timber usage to "store more carbon". I think you nodded toward this at various points in your review, and of course I think your assertion that "using less" is the way forward can only be the correct one.
(I know this comment was an unsolicited rebuttal to someone's else's argument, not yours, so feel free to ignore it, of course. I'm usually just a fascinated but unknowledgeable observer for your posts; this one happened to hit on an area I've done a bit of work in, so I took a little off-the-cuff stab at a response.)
Thank you for your comments. As you will note from my post, I have had some skepticism about the claims for mass timber, particularly about how much carbon is actually stored. In my book, The Story of Upfront Carbon, I list many of those issues and suggest that no more than half of the wood actually makes it into the CLT due to all the reasons you list, but conclude: “This is not all meant to be a criticism of mass timber! Every square meter of construction where wood replaces steel or concrete can be a plus for the climate, eliminating massive upfront emissions. It is instead a plea to use as little fibre as one can get away with when designing a safe and strong structure.” I think I might have to publish my chapter on this subject!
This is a reply from Paul Brannen, the author of ‘Timber! How wood can help save the world from climate breakdown’.
The first thing to say by way of response is that ‘Timber!’ is written from a UK/European perspective – not a north American one. As you know, forest growth dynamics differ with site conditions and forest types, and therefore between global regions. Hence growth dynamics in specific forest types in the Pacific Northwest differ from those in Europe.
It would therefore if others based in north America and specifically the Pacific Northwest could join this conversation.
To help me with my reply to your 'Assumption (1)' I have received help from the European Forest Institute https://efi.int
You note: “Assumption (1). Young trees sequester carbon at a faster rate than old trees of the same species. But the data doesn't support that: https://www.nature.com/articles/nature12914, one example of several I could link.”
As I see it, from a European perspective, the data does support ‘teenage’ and ‘middle aged’ trees absorbing more carbon than ‘very young’ and ‘old trees’. Clearly these are very general terms but to be specific we can look at Pretzsch et al. (2023) https://www.nature.com/articles/s41598-023-41077-6 (also in Nature) who analysed the forest growth trends in Europe, using 415 unique long-term experiments including 642 plots across Europe covering seven tree species and surveys from 1878 to 2016. Among their findings is Figure 1 on the overall growth trend across all species, showing a clear age dependent dynamics.
They also state: “Despite a high variation in the data, the model shows a plausible age trend for constant environmental conditions, i.e. maximum growth at young ages and gradually declining growth with increasing age.”
Sperlich et al. (2020) analysed forest productivity under climate change and present data from forest yield tables in Baden-Württemberg in Figure 3, again proofing the age-related growth trend: https://www.mdpi.com/2225-1154/8/12/141
Kindermann et al. (2013) used forest growth models and yield tables for different tree species and European regions. Figure 11 presents some findings, again showing the age-related dynamics: https://pure.iiasa.ac.at/id/eprint/10363/
As a conclusion: middle-aged (not too young) stands sequester annually more carbon than older ones (that might store more carbon than younger stands, provided there is no disturbance). Keeping forests younger leads to more annual carbon uptake than keeping old forests with their higher risk of disturbances.
That said it would be good to hear other north American perspectives – particular with regards the Pacific Northwest.
Lloyd! I share and appreciate the skepticism around mass timber, CLT, and to a certain extent even wood fiber insulation, dependent on sourcing. What’s it take for a smart guy like you to get on the Straw Train? Annual yield, incredible carbon storage potential, and we could superinsulate every new home with only 10% of the wheat straw we’re already growing for food production. I run a company that is dedicated entirely to storing carbon in buildings with materials like straw— Croft, also based in Maine. You are welcome to come visit us anytime and see real climate action occurring at our tiny but mighty prefab shop! ✌️🌍
One thing everyone forgets is the impact on local wildlife. For example, here in Tassie we have lots of gum tree plantations. When the one across the road from us was harvested 5 years ago, we were inundated with local wildlife that had been displaced. I hate to think how many were killed and maimed by falling trees, and that happens in every forest, every plantation, every time you harvest. There's no avoiding it really, critters live in trees, any trees, when all they have is millions of the same trees.
Paul here, the author of 'Timber! How wood can help save the world from climate breakdown'. First thing to say is that 'Timber!' was written from a UK / European perspective and not a North American one and I'm not well placed to make comparisons - I'll leave that to others. However on reading the article you cite from High Country News it's obvious this is an 'apples and pears' situation ie comparing the State of Oregon to the 'bigger picture' and / or Europe simply doesn't work. The conclusions reached by Beverly Law are not wrong but they are specific to Oregon. Hence CO2 emissions from agriculture in Oregon are 'low' and emissions from forestry & forest products are 'high' presumably because forest cover is much greater than agricultural cover? In Europe where land use between forestry and agriculture is roughly 50-50 then emissions from agriculture are much, much higher than from the forestry and wood products industry. Oregon presumably (correct me if I'm wrong) doesn't have any other industries producing large CO2 emissions so de facto the forestry & wood products industry is the 'big' emitter. Likewise the population density is relatively low at 40th out of the 51 states with the bulk of the population in the Portland area hence emissions from travel is 'low'. (I'm guessing air travel isn't factored into the figures for the transportation sector, although I could be wrong). To understand my argument I guess you need to read the book! On sale from September in the USA from Columbia University Press https://cup.columbia.edu/book/timber/9781788217354
I also question the way they partition the GHGs by industry. Don’t know if I raised that in this particular post. Also Oregon has wet and dry forests and there is this dry forest problem. Dead burned trees sequester no carbon, and are not good for wildlife nor watersheds. More recently I posted this about “carbon credits” and the potential impacts of those policies on adjacent forests and potential for beneficial fire. Bottom line- each forest is different and “leaving it alone” is not always best for biodiversity, watersheds, etc.
This is the "Yes But!!!" Issue. Cutting forests and trees for construction may help the building industry but long term it is not great for biodiversity that supports other key life processes on our Earth ship. Mono-culture of fast growing trees is generally a dead zone for critters and other plant diversity. The conundrum is to stop massive climate change but also continue supporting/protecting critical biodiversity. E.g., One could give massive amounts of NSAIDs to curb a high fever to a patient , but if long term this is also is destroying their liver, digestive system etc. so they may die early in any case does it really help? A conservation ecologists $.02 (US) worth.
Great article Lloyd - and you're right it is a great and timely book. I agree a race to the tallest is counterintuitive - if the reason we are building in timber is about sustainability, why build a non-sustainable model. We need to be mindful of every planetary resource that we use and therefore contemporary design needs to prioritise sufficiency.. there are more than enough buildings to be built where timber should be used and carbon can be stored. Intensifying the use of timber in any one building as a carbon store is nonsensical. Touch the ground lightly .. not with 18m piles.
Growing willow for insulation sounds fine. But it only works if we are already using all the wood fiber left over from making lumber. We aren't doing that now. Timber HP is the only US manufacturer of wood fiber insulation. It processes a tiny fraction of the slash/chips left from lumber making. Planting willow for insulation only means more slash/ chips left to rot or burned to make heat or power.
Great to read your review, Lloyd. I was almost losing faith at certain points but relieved with your conclusion! 😅
Love the thoughts on insulation and agree fast growing crops like willow hold great promise. (Back to traditional approaches like coppicing,with some updating and new applications!)
I still don’t buy the substitution argument though, other than as a possibly useful emotive one to make a point. Getting to low/net-zero emissions is about the real emissions that occur not fictional emissions that might have happened but were avoided.
I love your description of them as "fictional" emissions and thanks for editng substitution, as owner of the substack I was surprised that I couldn't!
Ha yeah I saw it immediately but couldn’t edit it on the mobile app. Had to remember to open in on the web on my laptop to edit it.
Substituting low-carbon materials for high-carbon materials WILL get us closer to overall low carbon emissions.
Yes but the emissions that count are those of the materials you actually use, not those you might have in a fictional scenario or a theoretical improvement.
If the building is going to get built, because there is a need for the space, then less carbon will have been generated by the lower-carbon materials than by the alternative higher-carbon materials.
My ingrained inclination is against one size fits all answers, we need a toolbox full of things but with a deeper understanding of the relative pros and cons of- the necessary trade offs between one solution or technology and another.
Robert, I agree, one size fits all answers rarely work. Hence I was careful with the title of the book ie 'Timber! How wood can HELP tackle climate breakdown', capitals added. I didn't say 'How wood can STOP climate breakdown'. Wood is not a silver bullet but it can play a significant role which amounts to at least 15 percent of the answer to climate breakdown.
"...Save the World from Climate Breakdown".
"Breakdown"???
Will ill-begotten euphemisms ever cease? I guess the reasoning must be "keep changing the words - we just might create a smidgeon of a passing flicker of interest in someone.
"showed a low rise apartment building built of Cross Laminated Timber (CLT), noting the wood in her company's Strandparken project was replaced by new growth in 44 seconds."
Are we REALLY supposed to blithely accept that "in 44 seconds" without hesitation. Thousands of board feet of wood used to erect an apartment building are replaced in less than a minute?
How many trees were harvested for that project and how long will it take for the replacement seedlings grow to the same level of maturity? C'mon, Lloyd...
I did not accept that. I disagreed and challenged it. read on!
standby - I shall.
Sorry Lloyd - after re-reading it 3 times, no mention is made concerning the 44 seconds. The only thing that comes close is the 602,280 seconds for growing a willow tree from a 30cm cutting.
Why do you have a probem with 44 seconds? Sure its a number plucked out of the air using dodgy maths but its probably close to that IRL.
Since there was not context applied with it, it's a real bad look for the quote/post - as if trees just spring up like Jack's Magic beans. And later in doing some other looking around, I saw some context elsewhere (have no idea if they are dodgy or not - I do think so) in that the reference MIGHT HAVE BEEN that it references ALL the remaining trees in the aggregate for that forest would replace the cut-down wood for the building.
I note that Lloyd didn't come in and rescue it when he said he challenged it and I didn't see the challenge in his post.
Words have meanings and they should be precise when used.
Well, I suspect they did the maths like this:
34% of the USA is Forrest
Oregon alone produces 3.8 billion board feet (whatever that is, why must you use such weird units)
Which equates too approx. 6,000,00 metric tons.
There are 31 million seconds in a year so that is 1 metric ton every 5 second.
so 10 tons is approx 44 seconds, but they were counting all USA not just Oregon.
I suspect that's how they did their maths approx.
Thats also about 1,600,000 of carbon. or 24,000 properties at 250 tons per property.
However not everything is good.
Industry emissions are approx 1,200,000,000. Of which about 15% is building or 108,000,000 tons (note numbers do not include power) so 1.487% reduction not counting the carbon emissions of providing all that wood.
So, in the grand scheme of things F**K All. (that's the technical term)
It would also of course need the doubling of the timber take.
Regarding insulation... what about Roxul & other stone derived insulation products? I had thought they had legitimately very low embodied GHG emissions, and would have much less land-use/biodiversity issues.
Legitimately sustainable sources of biomass are very much limited. And all sorts of industries want access. The Energy Transition Commission has the best resource I've seen on this issue: https://www.energy-transitions.org/energy-transitions-commission-warns-demand-for-biomass-likely-to-exceed-sustainable-supply/#:~:text=The%20Energy%20Transitions%20Commission%27s%20latest,use%20of%20bioresources%20carefully%20prioritised
It is also worth noting that there are major advances in cement and steel industries that could get these industries to zero emissions. It'll be 3-4 decades best case before these industries are completely decarbonized globally. But much more sustainable alternatives will be available to progressive designers & developers in the next 5-10 years.
I remain unconvinced, notwithstanding Lloyd's swayed opinion. Appreciate the great overview of the book though, Lloyd!
Hi Brendan - Paul here, the author of Timber! As I point out in the chapter on insulation in the book Roxul Rockwool is in most cases a major climate problem. Essentially it is made by taking rock / stone and then melting it into a liquid before spinning the liquid - as if making candy floss - before cooling it and making sheets of insulation. The problem with this is a very high temperature is needed to melt the rock/stone and this, in most cases, is achieved by burning fossil fuels - de facto you have large CO2 emissions. You could use energy from nuclear power or hydro which would be green energy but this is rarely the case.
The key question with the manufacture of insulation is therefore how was the energy made to manufacture the insulation irrespective of what the insulation is actually made from. A wood fibre insulation made using a wet process might involve using a large amount of energy to then dry the product. Did this energy come from burning fossil fuels? If so, like the Rockwool made with fossil fuels, it will have a high level of embodied carbon.
The fact that stone is a natural material does not make its use in making insulation a good thing. Why not? Because stone is not sustainable ie you cannot simply 'grow' some more to replace what you have used. Essentially it is a finite material. Often stone quarries near large centres of population have become exhausted leaving a moonlike landscape devoid of biodiversity. It is the same with limestone quarries where the key material for making concrete is mined.
Returning to insulation - while Rockwool and wood fibre insulation may both have high levels of embodied carbon as a result of burning fossil fuels during their manufacture only one of them - the wood fibre - can store carbon that has been removed from the atmosphere = a good thing. Consequently the insulation that is better for the climate will be the wood fibre insulation and if it has been made with green energy then even better.
Do we have enough biomass (woody fibre) to make massive amounts of insulation? Yes, we could have is the short answer. The longer answer forms four chapters of the book!
Cement and steel are both decades away from anything other than a very small amount of both materials being produced with low levels of embodied carbon and where it does happen it will be expensive.
Hope this all makes sense.
Hi Paul
Thanks for your extensive reply.
My understanding has been that rock wool insulation (like Roxul) have a carbon footprint today comparable to fibreglass batt insulation. See e.g. this article from Green Building Advisor - https://www.greenbuildingadvisor.com/article/does-your-insulation-have-low-embodied-carbon (This study is very friendly to bio-based insulation & other materials, BTW. As noted above & below, I question the logic that forest-based materials are "carbon negative"). As electricity & heat decarb, we can further decarb e.g. rock wool energy inputs - this is happening fast over next 1-3 decades.
I encourage anyone reading this to review the Energy Transition Commission's report
Bioresources within a Net-Zero Emissions Economy (https://www.energy-transitions.org/publications/bioresources-within-a-net-zero-economy/). It is excellent. What is makes clear is that the supply of legitimately sustainable biomass for building materials, plastic replacements, energy, etc. etc. are limited.
When we clear cut forests for wood, insulation, energy, etc. there are significant carbon cycle impacts. The forests that would have grown and absorbed more carbon are cut. Critically, soil carbon is emitted to the atmosphere in a large pulse due to the changes in local climate & hydrology. Jim Pojar (botanist & ecologist) does a good job explaining these dynamics for a fairly lay-audience - https://skeenawatershed.com/wp-content/uploads/2022/06/Pojar-ForestsAndCarboninBC-2019.pdf Forestry is not "climate neutral" as the industry has successfully led even thoughtful authors to believe.
Finally, Paul, respectfully, your argument that mining rock creates a "moonscape devoid of biodiversity" while we can "simply grow more [forests] to replace what we have used" is outrageous. It is a gross simplification of forests' value for biodiversity - young tree plantation style forests are often the ecological "moonscapes". And forestry takes so much more land to produce a given amount of material than mining rock. Take a Google maps tour of British Columbia's Chilcotin and Cariboo to see just how much land industrial logging impacts! And then check out some of the way that quarries have been restored to provide some biodiversity value and human amenity (I like this one - https://landscape.coac.net/en/node/8337). I'm not an apologist for mining/quarry's - they can devastate landscapes. But forestry can too, and on a much wider scale due to the inherent land-inefficiency of wood vs. stone.
Hi Bruce - as the author of Timber! I'd make the following points:
- if the priority is biodiversity, and only biodiversity, then humankind needs to depart the earth as our presence is without doubt a negative when it comes to biodiversity
- but that hopefully isn't going to happen
- as I point out in the book the global population is set to rise by an extra 2 billion by 2050 and they will all need somewhere to live
- as it stands most of them will live in mid-rise apartment blocks in an urban setting made from concrete & steel which together account for more than 12 per cent of global carbon emissions, that's more than the whole of Europe
- hence we need to switch to nature-based materials such as sustainable timber which can sequester CO2 when growing, substitute for more carbon intensive materials (the steel & concrete) and then also store carbon
- but yes, it has to be done sustainably and with due regard to biodiversity
- North America not my area of knowledge but here in the UK and Europe more widely we are improving in this area and aim to do better
- see re the UK https://www.confor.org.uk/news/latest-news/biodiversity-forestry-and-wood/
- see re Finland https://cdn.prod.website-files.com/5f44f62ce4d302179b465b3a/6524e21683a1c9a3a0d53e85_Metry_Monimuotoisuus_2023_eng_low.pdf
- replanting felled trees with only one species is an increasingly bad approach given climate change much better to plant a mix, as we do in Europe, as this spreads the future risk
- clearly not all forests should be available for commercial timber production we also need large areas of protected woodland where biodiversity is the priority but don't fall into the mistake of thinking it's an either or - it can be both.
Just bought the book - now to find time to read it!
Lloyd, I'm not sure about some of the assumptions that the author appears to have made in this book, if I'm understanding his argument correctly. I haven't read it, so maybe these were explicit in the book, or maybe hidden; regardless, pro-CLT/mass-timber messaging is big in my region and touches on the work I do, so I am familiar with many of the common talking points. It seems that this whole idea of mass timber as a climate solution (through carbon sequestration) only works if a few things are true:
Assumption (1). Young trees sequester carbon at a faster rate than old trees of the same species. But the data doesn't support that: https://www.nature.com/articles/nature12914, one example of several I could link.
Assumption (2). The carbon remains sequestered in a structure for longer than it would remain sequestered in trees (which could be one very long-lived tree with a lifespan of several hundred years, like our conifers in the western US/Canada (or oaks anywhere), or naturally occurring generations of replacement trees). For the carbon-embodiment in construction studies I've seen, the lifespan of a typical American building before demolition is assumed at 30 years. See here, noting that several decades is the presumed max: https://www.pnas.org/doi/10.1073/pnas.1720064115. Could we do better? Sure. But will we really design our wood buildings to last several hundred years? (I doubt it, at least not in the US.)
Assumption (3). Tree plantations on a frequent harvest rotation provide comparable carbon/climate benefits to functional forest ecosystems. Multiple studies have shown this is not true, not to mention it's obvious when considering an appropriate analogy. Ask whether a cornfield provides the climate benefits of an intact prairie ecosystem, and of course the answer is a clear no. https://academiccommons.columbia.edu/doi/10.7916/kc4f-j904
The author's argument also seems to work only if the complete carbon lifecycle of harvesting and processing wood into wood products is elided, at least in part. In my state of Oregon, researchers have quantified all that data, and when you offset for all the diesel fuel for the logging equipment, all the soil carbon (and sheer biomass of plants and animals) that's degraded and lost when the forest floor is exposed to skidding and sunlight), fuel for transport to mills on semi trucks, wood volume lost on the sawmill floor, proportional sawmill emissions, waste wood landfilled/burned, and used wood likely landfilled at the end of the building's (short) lifespan, only some small portion of the carbon embodied in the tree makes it into a building.
There's more, like the fact that just looking at carbon emissions/sequestration ignores all the other ways that intact forests contribute to climate regulation besides mere carbon storage. If CLT/mass-timber is a reasonable path forward, great, but it comes across to me like a false solution, especially when its proponents push for increased timber usage to "store more carbon". I think you nodded toward this at various points in your review, and of course I think your assertion that "using less" is the way forward can only be the correct one.
(I know this comment was an unsolicited rebuttal to someone's else's argument, not yours, so feel free to ignore it, of course. I'm usually just a fascinated but unknowledgeable observer for your posts; this one happened to hit on an area I've done a bit of work in, so I took a little off-the-cuff stab at a response.)
Thank you for your comments. As you will note from my post, I have had some skepticism about the claims for mass timber, particularly about how much carbon is actually stored. In my book, The Story of Upfront Carbon, I list many of those issues and suggest that no more than half of the wood actually makes it into the CLT due to all the reasons you list, but conclude: “This is not all meant to be a criticism of mass timber! Every square meter of construction where wood replaces steel or concrete can be a plus for the climate, eliminating massive upfront emissions. It is instead a plea to use as little fibre as one can get away with when designing a safe and strong structure.” I think I might have to publish my chapter on this subject!
Fantastic. Lloyd, I hope you do! I’d get a lot from it. Thanks.
Hi Rebecca
This is a reply from Paul Brannen, the author of ‘Timber! How wood can help save the world from climate breakdown’.
The first thing to say by way of response is that ‘Timber!’ is written from a UK/European perspective – not a north American one. As you know, forest growth dynamics differ with site conditions and forest types, and therefore between global regions. Hence growth dynamics in specific forest types in the Pacific Northwest differ from those in Europe.
It would therefore if others based in north America and specifically the Pacific Northwest could join this conversation.
To help me with my reply to your 'Assumption (1)' I have received help from the European Forest Institute https://efi.int
You note: “Assumption (1). Young trees sequester carbon at a faster rate than old trees of the same species. But the data doesn't support that: https://www.nature.com/articles/nature12914, one example of several I could link.”
As I see it, from a European perspective, the data does support ‘teenage’ and ‘middle aged’ trees absorbing more carbon than ‘very young’ and ‘old trees’. Clearly these are very general terms but to be specific we can look at Pretzsch et al. (2023) https://www.nature.com/articles/s41598-023-41077-6 (also in Nature) who analysed the forest growth trends in Europe, using 415 unique long-term experiments including 642 plots across Europe covering seven tree species and surveys from 1878 to 2016. Among their findings is Figure 1 on the overall growth trend across all species, showing a clear age dependent dynamics.
They also state: “Despite a high variation in the data, the model shows a plausible age trend for constant environmental conditions, i.e. maximum growth at young ages and gradually declining growth with increasing age.”
Sperlich et al. (2020) analysed forest productivity under climate change and present data from forest yield tables in Baden-Württemberg in Figure 3, again proofing the age-related growth trend: https://www.mdpi.com/2225-1154/8/12/141
Kindermann et al. (2013) used forest growth models and yield tables for different tree species and European regions. Figure 11 presents some findings, again showing the age-related dynamics: https://pure.iiasa.ac.at/id/eprint/10363/
Nagel et al. (2023) also found an age-depended dynamics of carbon storage in above ground biomass: https://www.frontiersin.org/journals/forests-and-global-change/articles/10.3389/ffgc.2023.1099558/full
As a conclusion: middle-aged (not too young) stands sequester annually more carbon than older ones (that might store more carbon than younger stands, provided there is no disturbance). Keeping forests younger leads to more annual carbon uptake than keeping old forests with their higher risk of disturbances.
That said it would be good to hear other north American perspectives – particular with regards the Pacific Northwest.
Thanks
Paul
Lloyd! I share and appreciate the skepticism around mass timber, CLT, and to a certain extent even wood fiber insulation, dependent on sourcing. What’s it take for a smart guy like you to get on the Straw Train? Annual yield, incredible carbon storage potential, and we could superinsulate every new home with only 10% of the wheat straw we’re already growing for food production. I run a company that is dedicated entirely to storing carbon in buildings with materials like straw— Croft, also based in Maine. You are welcome to come visit us anytime and see real climate action occurring at our tiny but mighty prefab shop! ✌️🌍
I am on the straw train! I wrote about it here https://lloydalter.substack.com/p/the-three-little-pigs-got-it-wrong
Lloyd, thanks again for a thoughtful look at our built environment, be it wood, concrete, or anything else for that matter.
One thing everyone forgets is the impact on local wildlife. For example, here in Tassie we have lots of gum tree plantations. When the one across the road from us was harvested 5 years ago, we were inundated with local wildlife that had been displaced. I hate to think how many were killed and maimed by falling trees, and that happens in every forest, every plantation, every time you harvest. There's no avoiding it really, critters live in trees, any trees, when all they have is millions of the same trees.
Brannen sounds like a great saleman, but I'm deeply skeptical. Here's an article about a study by qualified researchers that comes to very opposite conclusions: https://www.hcn.org/issues/50-11/climate-change-timber-is-oregons-biggest-carbon-polluter/
Hi Bryan,
Paul here, the author of 'Timber! How wood can help save the world from climate breakdown'. First thing to say is that 'Timber!' was written from a UK / European perspective and not a North American one and I'm not well placed to make comparisons - I'll leave that to others. However on reading the article you cite from High Country News it's obvious this is an 'apples and pears' situation ie comparing the State of Oregon to the 'bigger picture' and / or Europe simply doesn't work. The conclusions reached by Beverly Law are not wrong but they are specific to Oregon. Hence CO2 emissions from agriculture in Oregon are 'low' and emissions from forestry & forest products are 'high' presumably because forest cover is much greater than agricultural cover? In Europe where land use between forestry and agriculture is roughly 50-50 then emissions from agriculture are much, much higher than from the forestry and wood products industry. Oregon presumably (correct me if I'm wrong) doesn't have any other industries producing large CO2 emissions so de facto the forestry & wood products industry is the 'big' emitter. Likewise the population density is relatively low at 40th out of the 51 states with the bulk of the population in the Portland area hence emissions from travel is 'low'. (I'm guessing air travel isn't factored into the figures for the transportation sector, although I could be wrong). To understand my argument I guess you need to read the book! On sale from September in the USA from Columbia University Press https://cup.columbia.edu/book/timber/9781788217354
In the meantime take a look at this academic article as a useful starting point: https://www.nature.com/articles/s41893-019-0462-4
Sorry about that, here’s the link, couldn’t edit on my iPad https://forestpolicypub.com/2024/07/13/zeke-lunder-on-the-shelly-fire-and-carbon-credits/
Paul, the Law study has some serious problems, if you skip to the comments of folks with on the ground measurement experience. https://forestpolicypub.com/2017/12/13/report-timber-harvesting-is-by-far-the-largest-source-of-greenhouse-gas-emissions-in-oregon/
I also question the way they partition the GHGs by industry. Don’t know if I raised that in this particular post. Also Oregon has wet and dry forests and there is this dry forest problem. Dead burned trees sequester no carbon, and are not good for wildlife nor watersheds. More recently I posted this about “carbon credits” and the potential impacts of those policies on adjacent forests and potential for beneficial fire. Bottom line- each forest is different and “leaving it alone” is not always best for biodiversity, watersheds, etc.