« Thermoelectric Stoves: Ditch the Solar Panels? | Main | How and why I stopped buying new laptops »


Feed You can follow this conversation by subscribing to the comment feed for this post.

Rafael Carrascosa


Thanks Kris, amazing work



Thank you! I always thought of pure aesthetical reasons why pruned trees exist. I learned something today :)

Craig Macdonald


I found this piece very instructive and inspiring. I think it is going to change the way I restore a small plot of land we now own in southern France.

I would like to point out what appears to be an error in the text of Note [11]: I believe the word "easier" found in the first sentence ought to be "harder".



[14] is not linked in the article.



I was really looking forward to your announced new article and I did not get disappointed. You made a fairly good and balanced point.
I would question a bit about your relativization of the 2017 study text section. Their energy consumption is quite high, also the emission if you consider what is done with that energy. It is just used for a basic lifestyle mostly cooking, some heating, no industry. All shipping industry in the world takes 3% human CO2 emission. Also you have unfortunately no source for these interpretations you do why they are so efficient or if they really use wood like you proposed. From my limited education on that field I do not think they use these technics, for example in India at the Himalayans, big areas were cut down by poor people so radically, that erosion take over immensely. https://www.indiatoday.in/magazine/environment/story/19760515-problems-of-deforestation-and-soil-erosion-in-himalayas-819149-2015-04-04
This article suggests for example that the people there also use wood like Brazilians do, they cut it away and use it for livestock and cultivation separately.
But I recognise your intent that is telling that every culture should reconsider their wood sourcing and that pruning trees might be the way to go. Which I would actually want to agree with. I have also read that small growing trees take so much more CO2 out of the atmosphere than grown-up trees.
What you did not consider from my comment under your mentioned last article are several but I pick a few: For climate change it is relevant not only the CO2 but also the dust particles emitted from stoves. And even "clean" stoves are really dirty considering improper usage and not attentious supervision of process. http://www.soliftec.com/PhD_Ricardo_Luis_Teles_de_Carvalho.pdf
Also this article now only justifies burning wood as CO2 balanced with ecological benefits for nature. But it does not weaken my point that an electrical system will be cheaper and offer more economic opportunities than sustainable burning wood. It does not increase total energy efficiency even though you outlined an efficient local economy, the constant burning is so inefficient that you can transport a solar cell from China and have a small battery for 20 years is possibly same efficient but without the labour and the potential with illumination and electric transport. I do not have a scientifiy proof but a practical one: Solar is becoming more and more widespread even in poorest regions. The question is, if batteries will too, after economics of scale is full running.



I'm looking forward to seeing a 20 or 30 million people conurbation heated with coppiced wood. Let's get real. These techniques are suitable for small communities, as in villages, not for bilions of people.

Laszlo F.


I come from an area with great history and pride in sylviculture & forestry and thus I always wanted to believe that forests can only exist detached from agriculture. After all, who would like to associate themselves with smelly farms, dung and peasantry when you can dress in an all green uniform and sing hymns about nature all day? Looks like I was terribly mistaken, those dehesa landscapes are mesmerizing and seem like a bloody smart solution to combine wood production with agricultural activity. Though I imagine with all the invasive species and weeds growing everywhere it can be a pain to manage them, especially in contemporary Europe (full forest cover can mostly eliminate that problem).

@Daniel: Solve a problem today, have one less tomorrow. There are estimates that the ongoing COVID pandemic may set back the course of global urbanization by qutie a few years. Millions of people around the world won't be moving to cities as forecasted, but remain in villages and townships and keep heating with locally produced wood. So despite the fact that pruning and coppicing scales awfully, it can have an effect in many developing areas.

kris de decker


@ Daniel

The cities we take for granted now are products of fossil fuels.



@Kris de Decker

I don't think our cities are necessarily products of fossil fuels. Keep in mind that urbanisation is a process which started even before large scale charcoal production in middle ages began. There is reason to assume the accumulation is human wealth gathering achievement.

In Germany, there is serious discussion if hedgerows should be reestablished. There is even some funding for it. Also there is a bigger plan to interconnect natural habitats, to reestablish migration, so the animal gene pool is healthy. Also I would count the established bush planting and frequent pruning along the Autobahn and rails for example as pretty much the same system. The wood gets chipped and pelleted and burnt in wood chip plants.
Just because urbanisation might slow down it does not mean there is a trend reversal. But that would be needed, if you assumed that burning wood on an end consumer level is the future.

joel LeGrand


I am a big fan of the Rocket Mass Heater:
A rocket mass heater is:

cheap to run. About a tenth the cost of natural gas, electric or conventional wood heat.
clean. They emit about a hundredth of the smoke of a conventional wood stove.
good for the environment. Less than 2% of CO2 emissions of natural gas or electric heat. Can reduce your carbon footprint as much as parking 7 cars.
sustainable. It uses a renewable fuel which is easy to find and store.
cheap to build. About $200 to $600.
quick to build. Often built in a weekend
luxuriant. Like the luxury of a heated floor but without all that standing.

Bruce Teakle


Thanks Kris for another excellent essay. I congratulate you on persisting with describing the importance of traditional wood energy use, despite some negative feedback.
Considering the negative feedback, clearly from people holding genuine concerns about environmental issues, 2 issues appear to me.

The first is theoretical: understanding how the carbon cycle works. Forests are not a carbon “sink”, into which modern humans can dispose their fossil fuel CO2 emissions, they are a carbon store. Forests hold a limited capital of carbon, cycling a little as leaves rot, trees die, and new growth occurs. Every stick and leaf that is formed by plants will return its CO2 to the air, when an animal, microbe or fire harvests its energy. For the entirety of human existence, we have been part of that cycle.

Only rarely is the carbon stored as peat or charcoal for longer periods - our modern growth and climate problems come from having discovered how to burn these long-term stores.

The second is practical: if you don’t work in the forest, it’s hard to understand the practical manifestation of the carbon cycle. If you work in reforestation or in restoring the health of existing forests, the surplus of waste wood can be overwhelming.

In Australia, where most of our forests dry and burn periodically, the Aboriginal people developed sophisticated systems of cool burning that managed fuel loads and protect the forest from hot fires. White people took the traditional owners and their fire practices out of the forest, so fuel loads escalated.

Now, enhanced by warming climate, hot bushfires burn up the carbon capital of the forests, not just the cyclic accumulation, with terrible ecological and human consequences. Fixing these forests requires dealing with a huge surplus of fuel.

Clearly wood can’t provide the energy to run the huge population and rapacious lifestyles of modern humans, but it is a valid and sustainable fuel when used in a balance.

David Bourguignon


Thanks Mr De Decker for this great review of one of the remarkable achievements of the "rural civilisation" of our European forebears. I fully agree, since it is still the lifestyle of so many people on this planet, it is worth considering.

However, either coppiced or pollarded, all these trees are only what is left of gigantic forests and as such, they cannot deliver even a fraction of the ecological functions originally delivered by these ancient forests, which were major contributors to the planetary life-support system before the invention of the "rural civilisation" 10,000 years ago. (Among these ecological functions, water cycle management, for example, which is now also threatened by GHG-induced radiative forcing, putting into jeopardy this very same "rural civilisation".)

Moreover, as you already know, heavy deforestation was not invented by humans after the discovery of fossil fuels. Europe was covered by forests after the end of the last Ice Age and agricultural practices coming from the Middle East deforested it quickly. In fact, the "industrial civilisation" invented way before the 19th century, during Antiquity, was built on top of the very same extractive principles as the "rural civilisation" (deforestation, loss of top soil and water). The situation was already terrible before the 19th century, fossil fuels simply made this more obvious by accelerating the trend.

Maybe it is time to rethink our situation in a completely different way and consider the past has very little to teach us, as we are now leaving the climate steady-state of the Holocene? I like this quote: "You could not step twice into the same river." (Heraclitus)

All the best, and thanks again for all these stimulating reflections.

kris de decker


@ David

I am not sure what you want to say. That we should restore the planet in the state it was before humanity flourished? Why? All species leave their footprint on the landscape. The problem is that our footprint has become very destructive.

Preindustrial society was not a paradise of sustainability, and of course deforestation did happen. But fossil fuels have changed everything. They have removed all limits. For example, although there was deforestation in the past, the planet never lost all its forests because many wood reserves were simply inaccessible. Today, worldwide deforestation is a real risk, cause there are no more limits. We now have the technological means to harvest all the wood in the world. We simply could not do that before fossil fuels.

There's a great book about this topic: Sieferle, Rolf Pieter. The Subterranean Forest: energy systems and the industrial revolution. White Horse Press, 2001.

Gregory Corning


I note that the much-hated exotic invasive Siberian elm (Ulmus pumila), which grows fast and spreads very fast here in New Mexico USA, is excellent for coppicing, based on my experiences. Maybe coppicing can be a way to manage invasive species while getting some benefit from them.

Fin Butler



Also coppicing and the like doesn't need to be done to every last bit of the landscape, and I see no reason why dense "wild" forests and coppicing practices wouldn't exist together (in fact if I bothered to do research right now Im sure I could find examples of such).

As well, we have much better information sharing currently (and even transitioning to lower tech life style is one of the things I expect us to keep (even if we switch to other methods)) so avoiding mass deforestation is certainly practicable, especially if you remove the incentives to deforest. Agreed on Kris De Decker's points.



@Bruce Teakle

In a healthy climate I would totally agree. But you have not considered that our stable climate is based on a huge reduction of former CO2 from our atmosphere. If we had not risen the CO2 levels by the fossil fuels we could burn almost as much forest we liked, it would return to the trees like you described and stayed in normal cycle.
But now we have the situation of climate change, with too much CO2 in the atmosphere. So one of our only solution to get it out is photosynthesis, because the oceans can only bind so much and their Carbon sink rate is pretty slow. So instead of wasting this machinery that produce potential locked Carbon in plant matter and burn it right away, it is very important to store that plant fuel as long as possible. Either in wooden buildings, or any other product that is stable.



@Kris de Decker

I like the idea of making it uneconomical to cut trees from everywhere. I always like solutions that give strong incentives instead of permits. The European Union did great with their CO2 emission trading. I am not so sure if therefore we need to abolish our technical capabilities that are not bound to fossil fuels anymore. You say there is a direct connection, I would say this connection is not there anymore. Today we could also cut down all forests without emitting CO2. We have the means of transport, the knowledge (especially about the potential value, the demand, and by satellites where to find it) and rising demand for "green" fuels.
We needed to find another way of making forests more valueable by managing them sustainable and most CO2 effective (and maybe anti fire effective like s.o. said), instead of destroying these plants totally and their bound CO2 (the biomass). Your proposed forest and field management could be a thing to look at as legislative authority.

David Bourguignon



What I am trying to explain is simply that looking at the past to guide the future can be sometimes misleading, in particular when dealing with complex systems which are experiencing hysteresis. There is a current theory pretending we could go back to a "rural civilisation" and this would address our issues, but it is probably another illusion.

Low-tech Magazine work is invaluable to ask questions and make us think about the past, since learning about ancient ways can allow to continue using them in specific contexts or to get inspiration from them, but IMHO this practice will not be sufficient to address the immense global challenge we are facing.

There is this strange idea that global ecosystems could support more and more humans and their continuous biomass extraction behaviors, and still function properly. Quick fact: above 20-25% deforestation (caused by rural practices and population growth in Brazil), the Amazon rainforest will turn into a savannah biome. This will happen very soon and will transform the water cycle of the Americas and beyond, putting in jeopardy all kinds of agriculture (organic or not, they need rain).

Therefore, we might have to truly change our ways, that is give up for good:
- a 2M years old energy production system based on burning dead carbon
- a 10k years old food production system based on deforestation then soil+water abuse by cattle&crops
To sum up: we need entirely new ways of thinking and this is urgent.

Please consider also these simple facts in your reasoning: in Western Europe, at the end of the 18th century, in a fully "organic", "pre-industrial", "low-tech" world, after millennia of "rural civilisation", the land was heavily deforested and degraded. France, for example, reached its minimum forest cover ratio around 1850. However, the water cycle at the global scale was still operational, since huge intact forest biomes in the Amazon & Congo basins, South-East Asia, etc., were delivering their contributions to the planetary life-support system.

Now that people are deforesting these biomes too (as Europeans did of their own forest biomes to create their "rural civilisation", so why are we complaining), massive disturbances in the water cycle are now happening, made worse by our GHG emissions. This is not at all a surprise and will simply render all biomass-based strategies for the future completely obsolete within a short time frame.
To sum up: we might simply have to say farewell to this "rural civilisation", whether we desire it or not.

kris de decker


@ David

So what are these "entirely new ways of thinking"?

Do you advocate to go back to a hunter-gatherer society? Or is sophisticated technology involved?

Bart Vanden Driessche


@Kris de Decker

I think David suggests that we should move to agroforestry and maybe foodforests.

Although I think wood for heating and other uses discussed in previous articles.

It is also important to know that coppiced has other use then being burned as wood or charcoal. It was often used in buildings as construction materials and basketry.
as example daisugi in Japan

There was last year a reportage on ARTE named The beauty of pollards.

Hanno Hodgkin


I'm all for deconstructing the high energy society in which we live, and really want to be able to support seemingly sustainable systems like coppice management.
But as a market gardener and small farmer my attitude is that what is grown on the land must stay on the land. My intuition says that if I grow a crop of hay and sell it to my neighbour, hence returning nothing to the soils that grew the hay, my soils will be depleted, and over time my hay crops will decline. Thus we only sell the small amount of biomass we 'skim' off the top of the farms nutrient and energy cycles, the rest of the biomass 'life' if you will, being kept on the holding.
i.e. the vast majority of the biomass of the holding musty stay on the holding or else the overall productive capacity of the farm will decline.

So, given I really want to believe in low impact forrest management techniques which can give me timber for building and wood for burning, can someone please explain. How does this not in the longer term decrease the 'life' of the farm/capacity/health of the soils?
If I just burnt my hay every year, even if the ash was returned to the land, over time the capacity/potential of my soils would decrease and yields would fall. Why is forestry different? Can we harvest close to 100% of a coppice crop and burn it without gradually undermining the capacity of the land/soil to create biomass, without undermining the 'life' of the land.

David Bourguignon



First and foremost, thinking in terms of binary alternatives (low-tech vs. high-tech is my favorite, since no one agrees on what these popular expressions mean), is not really my way of considering the sustainability debate.

Given the constraints I presented briefly previously, a new way of thinking starts with the recognition that the continuation of the rural civilisation invented 10k years ago is not a solution, but the main problem we are now facing. In fact, biomass extraction by the rural civilisation has always slowly degraded the quality of the planetary life-support system, has always fostered population growth and the advance in extractive technology (which is not at all the invention of the industrial civilisation, it has always been part of the rural civilisation, which follows the same paradigm).

To answer your question, there could be several complementary ways forward (I do not pretend to have considered them all):

- On land, where most photosynthetic plants grow, and where forest biomes in particular manage the water cycle, which is essential for humanity activities outside of agriculture, we must operate land rewilding on a large scale, and maybe practice very-low yield extensive food production in those ecosystems (this has been experienced by humanity already, you could consider this as hunter-gatherer technology if you want).

- At sea, where most of the animal life exists on Earth, humanity could create the conditions for photosynthetic plants to grow (eg. seaweed farms on artificial structures), defining a new frontier for a new kind of "gardening" (you could also call it hunter-gatherer technology if you want, since this is very extensive too, given the surface available and the uncontrollable growth conditions).

- In cities, where most humanity will live in a few decades, we must develop an efficient "post-agriculture" focusing on either very high-yield intensive and controlled ecological farming (eg. aquaponics) or new forms of "breeding", ie. insects, or "brewing" of micro-organisms (bacteria, yeast, fungus) from either byproducts of the former "farming", or directly from atmospheric carbon dioxide, water and sunlight, using chimiolithotrophic or photosynthetic pathways (there is no sophisticated technology involved, but still many practices to be discovered yet).
Of course, there will still be a few traditional farming remaining, but without cattle very probably. If you are interested, there are many studies and reports on all this.

As a conclusion, I would say that, as hunter-gatherer civilisations were overthrown by the rural civilisation 10k years ago, which transformed the planet and humanity forever, now it is probably the time for this rural civilisation to disappear:

- Its land-based power system (from agriculture to mining) and extractive practices (from ecosystem biomass to metallic ore) can no longer address the issues humanity is facing.

- The entire sector, from the small farmer to the large industrial agribusiness, will be probably unable to cope with the rapid change in climatic conditions which will occur in the coming decades.

This change in civilisation could allow for the development of more efficient ways of producing food and energy for a larger human population, while regenerating the planetary life-support system in the process.


Agroforestry is certainly an interesting approach in specific contexts and on a short time frame but it is only an intermediate step and will never be part of the solution that will truly tackle our most urgent issue: the progressive degradation of the main constituents of the planetary life-support system, which allowed humanity to thrive over the past 15k years.

Regarding "food forests", I am not sure how you define them, but if they mean "managed wild ecosystems delivering extensive low-yield food production services" I agree it could be part of the vision I briefly presented.


You are very right. This is what most biomass advocates do not want you to think about: no matter how you see it, their approach is extractive, not regenerative. Wild ecosystems do recycle everything in very short-distance loops, without humans involved. The argument of atmospheric circulation recycling through carbon dioxyde is part of what is now known as "the UN Kyoto Protocol carbon neutrality accounting fraud". There is currently a huge scientific argument against this fake science approach and hope that at least EU policy will take that into consideration soon.

kris de decker


@ David

High-tech and low-tech are not "popular expressions". They are clearly defined adjectives. I quote from the Cambridge dictionary:

High-tech: Using the most advanced and developed machines and methods.

Low-tech: Not using the most recent equipment or methods.

As for your new ways of thinking, I cannot see what's new about it, and I am not impressed. It sounds a lot like the Venus Project.

@ Hanno

I agree. But as far as I understand, that was the case. Coppicing was local. Everything a coppice forest produced was eventually returned to the soil. Furthermore, animals were used to fertilize coppice forests. Humans ate the animals, and human waste was also returned to the soil.



What I like and highly appreciate from low-tech magazine is, that you find clever old techniques and other mind set approaches that can be reconsidered for our modern world. Nobody would really want a world where the newest tech is negated and stigmatised as the source of all the bad things. High-tech helps in many ways to have a better life on earth but these advances are all the time thematized by most media. So the low-tech side gets here a representation. But it is no decision between two poles. Our information age allows us to reconsider forgotten techniques better than ever before, when it was mostly driven by heriting from the direct ancestors or the surrounding population.
If the goal of the article is to make woods cultured sustainable, in energy sourcing matters I will suggest to at least gasify the biomass and then burn it or better use the material first for useful items like cardboard and then burn it in cogeneration. Better of course it is turned into longterm products like houses. That is really sustainable, because in our unsustainable world it is not sufficient to just do no further harm, but make it better.




Thanks for another enlightening article.

I very much would like to recommend the work of Ben Law in England (e.g. his book "The Woodland Way"), mainly focussed on living in the forest and living off the forest. He stewards an area of mainly sweet chestnut coppice that is centuries old.

Regarding lime trees (Tilia cordata) - the fresh leaves are also edible for humans. And delicious. Unfortunately the gastronomical use has been largely forgotten. I maintain a small hedge of lime trees for salad use in our garden.

And of course the global population and energy use will go down considerably. Either in a planned way or unplanned.
What is not sustainable will eventually stop...

Thanks again,

David Bourguignon



Well, with all due respect to the Cambridge dictionary, I am afraid those definitions are of little use. In fact, if I follow them, a technology of today is high-tech wrt to a technology of yesterday, but will be low-tech wrt a technology of tomorrow. Let us wait then, for what people consider bad/ugly now, to be transformed into something good/beautiful? IMHO we will need to build our sustainability strategies on firmer ground.

"Your new ways of thinking" are not mine at all. These ideas and facts come from a review of the scientific literature.
I am preparing a bibliography ranging from the UK Committee on Climate Change reports, to peer-reviewed journals such as Nature and Science, to public white papers from innovative companies such as Solar Foods. I can send you this list when it will be ready, if you are interested.
BTW I had never heard about the Venus Project before. I checked the website and do not really understand your comparison, to be frank, since I am not talking about Utopian fantasies but real, existing solutions.

Thanks for this conversation. I learned a lot, but not necessarily regarding sustainable biomass. I recommend your readers to check what will come out of the coming revision of the EU biomass policies, which I hope will be inspired by the most recent recommandations of the joint declaration of the European academies of science.
All the best.

kris de decker


@ Goran

Thanks !

@ David

"In fact, if I follow them, a technology of today is high-tech wrt to a technology of yesterday, but will be low-tech wrt a technology of tomorrow."

This is exactly the point. This is what Low-tech Magazine is about. Our society continues to be focused on technological progress and tech solutions, while we have long invented every technology we need. Technology has become a problem instead of a solution. We need to innovate in different ways. For example: social innovation, institutional innovation, economic innovation.

The direction you suggest doesn't seem to include any of that. But feel free to send me any information you like.

David Bourguignon



Thanks for this complementary info. Now I start to understand a bit better what Low-Tech Magazine is all about. Therefore, I suggest the following definitions for low- and high-tech and they have nothing to do with technologies themselves and their relative oldness/newness, since IMHO this ends up with non-operative definitions. (And your strange statement: "we have long invented every technology we need"... How do you know that, if we do not know what we do not know, as any scientist would say?)

My alternative proposal:

- High-tech: Using a high proportion of technological innovation and a low proportion of other forms of innovation (social, institutional, economic, etc.)
Example: using autonomous drones for reforestation.

- Low-tech: Using a low proportion of technological innovation and a high proportion of other forms of innovation (social, institutional, economic, etc.)
Example: using satellite Internet mobile communication to help local communities develop their own network of local native tree species nurseries, fostered by timebanking transactions.

As you noticed, I avoided on purpose focusing on the age of the technology and rather focused of how much of it is used in developing the entire solution. Maybe better examples could be found... What do you think?

Last but not least: "The direction you suggest doesn't seem to include any of that [other non-technological forms of innovation]." Well, on the very contrary... They are intensely low-tech, but still relying on tiny pieces of technology that are yet to be developed. Therefore, we will need to invent a few new technologies and methods for reaching transformative objectives.



This article inspires me :)

As for the reportage mentioned by Bart Vanden Driessche in comment (20), it is from Timothée Janssen (France, 2017, 52minutes), freely available in French until October 18th!


Thomas Reis


Everybody who has a horse knows how much litter a horse needs. Towns used a huge portion of green brushwood. So a whole race lived from collecting brushwood in German also called Reisig, my surname derives from this practice. You find many pictures about 'Reisigsammler' on Google. And until today 'Schnittreisig' is cultivated from conifers. https://de.wikipedia.org/wiki/Datei:Gewinnung_von_Schnittreisig.jpg



@ David Bourguignon (#22)

"In fact, biomass extraction by the rural civilisation has always slowly degraded the quality of the planetary life-support system, has always fostered population growth and the advance in extractive technology"

This is quite simply not true. When you have a localized rural economy the biomass production largely stays local and greatly enhances the biome.

For an example of this see anthropogenic soils.



On the subject of pollarding, coppicing, etc. in my home county in the UK, (Suffolk) there were many hedgerows that had multiple uses, including providing firewood, control of animals etc. and had been there for hundreds of years.
However, many farms were bought by the 'new rich' when the old farmers retired, or died and there was no family available to continue the farm. These 'new rich' farmers eyed the hedgerows as wasted space, on which they could grow crops and rake in more cash, so in many cases, the hedgerows were bulldozed out, and resulted in what the locals called ''prairie fields''!
When the hedgerows went, so did the many birds that used to nest in them, but the millions of bugs that they used to eat, were now free to propagate and attack the crops. Also, the weed seeds that the hedgerows trapped, were now free to spread across the fields unchecked, as were mice and other crop eating animals, as the homes of their predators were also destroyed. Also, the winds that the relatively flat land is prone to were blowing surface soils all over.
This meant that the crops needed herbicides and insecticides, and additional fertilisers, together with the labour and tractor fuel to distribute them.
Eventually the farmers worked out that they were spending more on these than they were recouping from the additional crops, so were then persuaded to start replanting the hedgerows.
They might have worked out that if the hedges had been in existence for hundreds of years, that they had a serious purpose, or the would not be there.
Please be advised, that the idea that human produced CO2 is the cause of ''Global Warming/climate change'' is a political myth/scam, and is utterly ridiculous. The present level of CO2 is around 400 ppm, which is the lowest for 270 million years, since the Permian extinction. The human content is about 10%, or 40 ppm which is quite incapable of having any effect on anything.
This graph shows it all;
It can be seen that there is no correlation between CO2 and global temperature.
In addition, the planet has been in an ever deepening Ice Age for the last 40 million years or so, which has many tens of millions of years to go before the planet will return to normal average temperature of approximately twice current.

kris de decker


@ Worzel

It may well be that the temperature is the lowest in 270 million years, but who cares? Humans can only survive within a limited range of temperatures, and we haven't been around for 270 million years.



@kris de decker
I think you've missed the point entirely.

kris de decker


Then go ahead and explain me. I am not an idiot.

Brian Sawers


Thank you for your articles at Low Tech and No Tech. I think both are great resources and very interesting.

I live in Slovenia, where a large share of houses are heated with wood. The masonry stove is common, although a few homes have wood stoves made of steel. I have never seen an open fireplace. Air quality in the heating season is poor. If there is little wind, air quality is terrible, especially in narrow valleys. Many people burn green softwoods instead of cured/seasoned hardwoods. A few people burn pallets and offcuts of engineered wood, which are probably more glue than wood. Judging from the color of the smoke, many people are setting low temperature fires.

Burning cured/seasoned hardwoods at higher temperatures should improve air quality. But I suspect that better burning won't improve air quality enough to remove the threat to human health. Furthermore, whatever gains from better burning would be swamped if people currently heating with fossil fuels switched to wood. Slovenia is one of the few places where biomass could provide all of our heating and domestic hot water even without a return to coppicing. But I don't see how that's consistent with human health.

If biomass is the only climate-sustainable source of heat, then Slovenia is not sustainable, except at the cost of human health. Perhaps a much smaller population could live here, small enough that each family only breathed their own woodsmoke. Then, it seems like climate-sustainability requires a large-scale migration to warmer climates. The only places with a real winter where people can safely rely on biomass would be flat and fairly windy. Even in those places, the population density would have to be low.

Internal migration within Europe seems to move people from where the heating demands are low (Iberia, Italy, Greece) to places with higher heating demands (Britain, the Low Countries, Germany). Only the depopulation of the Baltics is a win for the climate. In North America, the trend is somewhat better where there is migration from the northern USA to the southern USA, although Canada continues to grow quickly.

I would love to hear your thoughts.


kris de decker


Hi Brian,

You ask a relevant question that I left out of the article on purpose because it deserves an article on its own. It is possible to greatly improve the health outcome of wood heating, for instance through wood gasification and very high combustion temperatures, such as those in tile stoves and masonry heaters. Stoker skills could also be improved.

I don't think we need to go back in time, or stick to the status quo of wood heating as it happens now. Up to a certain extent, sustainability can be in conflict with human health, but before I come to conclusions about that I would need to investigate how far we could improve wood burning technology in different contexts.

All the best from Spain,

Brian Sawers


In Slovenia, the most obvious improvements are better fuels (cured hardwoods, no scrap wood) and better stoking. I continue to be astonished that people who light 100+ fires a year cannot light a hot fire, but the smoke does not lie. But I am not very optimistic. Most houses already have a tile stove (called a peč). Many people cut their own firewood, which appears to be softwood exclusively. Lastly, people seem to have very little concern for air quality, even though we get a daily reminder. When the air is clean, the mountains are clearly visible. So any improvement would have to be both cheap and easy, since so many are not interested in paying more for something they don't value (cleaner air).

It would seem our environmental problems would be simpler to solve if more people lived in places with low energy demands, like Spain or Southern California. If anything, I read (Canadian) environmentalists praising living in places with hard winters and cool summers.

Sébastien Dawans


@Hanno Hodgkin

Perhaps there is a distinction to make in your discussion: annual crops vs perennials (trees).

You are right in that most annual crops, even when leaving on-site all the extra biomass, will still result in a net exportation of organic matter. This requires a constant re-supply in the form of mulch, compost, green-fertilizers...

For trees though, it's a bit different. The permanent presence of a tree tends to increase the carbon content of the surrounding soil over time. The principle carbon source being atmospheric CO2 in photosynthesis, the carbon reserves in the soil do not get depleted. In fact, they increase through 2 processes:

1) Deposition at the surface (leaves, small branches), which eventually get composted and form a layer of soil.
2) Rhizodeposition, which is complex but includes a net flux of atmospheric CO2 to organic C in the soil over time.

Verify your Comment

Previewing your Comment

This is only a preview. Your comment has not yet been posted.

Your comment could not be posted. Error type:
Your comment has been saved. Comments are moderated and will not appear until approved by the author. Post another comment

The letters and numbers you entered did not match the image. Please try again.

As a final step before posting your comment, enter the letters and numbers you see in the image below. This prevents automated programs from posting comments.

Having trouble reading this image? View an alternate.


Post a comment

Comments are moderated, and will not appear until the author has approved them.

Your Information

(Name is required. Email address will not be displayed with the comment.)

Get Updates


Search LTM + NTM