No doubt globally we need new construction. A new study from the Potsdam Institute for Climate Impact Research shows the benefits of timber construction. Environmentalists, however, say replacing natural forests with wood plantations to realise shift in construction practices is ‘bonkers’ In an article on The Guardian website, Arthur Neslen discusses the study and the reaction.
Timber cities ‘could cut 100bn tons of CO2 emissions by 2100’
Building new urban homes from wood instead of concrete and steel could save about 10% of the carbon budget needed to limit global heating to 2C this century, according to a new study.
The overhaul of construction practices needed for such a shift would require up to 149m hectares of new timber plantations – and an increase in harvests from unprotected natural forests – but it need not encroach on farmland, according to the paper by the Potsdam Institute for Climate Impact Research (PIK).
Housing 90% of the world’s growing urban population in mid-rise wooden buildings could prevent 106bn tons of carbon emissions by 2100, says the research.
Abhijeet Mishra, the paper’s lead author, said: “More than half the world’s population currently lives in cities and by 2100 the number will increase significantly. This means more homes will be built with steel and concrete, most of which have a serious carbon footprint. But we have an alternative. We can house the new urban population in mid-rise buildings – that is four to 12 storeys – made out of wood.”
The study, published in Nature Communications on Tuesday, is the first to analyse the scale of emissions cuts possible from a large-scale transition to “timber cities”.
Using four different land-use scenarios, PIK scientists used the Magpie open source global land use model to explore the impacts and practicalities of the “timber cities” idea.
Their reasoning was that wood has the lowest carbon footprint of any building material, because the carbon dioxide absorbed during tree growth will not be emitted until the timber is finally destroyed.
Alexander Popp, a co-author of the study, said that preventing logging for timber in pristine forests and biodiversity conservation areas was crucial to their calculations.
“The explicit safeguarding of these protected areas is key but still, the establishment of timber plantations at the cost of other non-protected natural areas could further increase a future loss of biodiversity,” he said.
Environmentalists, though, point out that the world’s 131m hectares of tree plantations tend to be less biodiverse than natural forests and burn more easily.
Sini Eräjää, Greenpeace’s European food and forests campaign lead, said it would be “a terrible idea” to cut down natural forests and replace them with wood plantations.
“It would be a disaster for nature and for the climate,” she said. “Natural, biodiverse forests are more resilient to drought, fires and disease, so are a much safer carbon store than the tree plantations we’ve seen go up in smoke this summer from Portugal to California. Wood can play a bigger role in construction but to double the world’s tree plantations at the expense of priceless nature is just bonkers, when modest reductions in meat and dairy farming would free up the land needed.”
Mishra accepted that wildlife loss would occur with tree plantations and called for “strong governance and careful planning to limit negative impacts to biodiversity”.
“Bio-physical risks” such as the potential for city wildfires to become more common had not been assessed in the report, he added.
Wood is still preferred by US house builders but as wildfires have intensified amid worsening climate disruption, some have questioned the practice of building with flammable materials.
Abhilash Panda, the deputy chief of partnerships at the UN Office for Disaster Risk Reduction in Geneva said: ”Wood does provide benefits. It provides a carbon sink, reduces emissions, and provides a way to address unmanaged forests. On the downside, it is flammable. However, what matters the most in determining fire risk is what type of housing is being considered, who is the target and what is the location. Risk is location specific and any design needs to embed resilience in it.”
About 15bn trees are globally felled each year at present. The planet’s tree population is thought to have almost halved since the dawn of human civilisation.
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Energy in Demand - Sustainable Energy - Rod Janssen 
Not mentioned is the reality that wooden houses can be (and are) pre-fabricated in factories. This leads to on-site erection in one-day. This is a fact because I know a chap in Belgium who has one. It took one day to put it together and connect all the services. This approach leands itself to locations such as Ukraine – which will need to rebuild post-war. Furthermore, there are plenty of good examples of using bamboo as contruction material in Central America – replacing concrete breeze blocks and corrugated iron – resulitng in a house that is much cooler and zero carbon.
Mike, you make a very important point. I’m originally from Canada and we largely have timber construction and more and more there are pre-fabricated buildings from factories (my sister-in-law’s place for one). The important point is sustainable forestry. I think there is a future but it has to be well planned and thought out.
I agree 100%. Of course one can also use recovered timber (of which there is a great deal) – which takes the pressure off using forests. No reason why this could not work – just needs imagination and – with respect to timber sourcing – very careful management and control. (& I know Arthur when he was in Bx).
Absolutely, one can use recovered timber. My father built our family home (now sold) from an old barracks that he dismantled. But where we lived, the forestry company was American. The wood had to be transported about 300 km or so to the US and then it had to be re-shipped back to us if we wanted to buy it. Nuts! Hopefully that sort of practice has stopped. It was quite a while ago.
The great supporters of buildings being pre fabricated, usually in a single location, should logically be organised labour. It is a lot easier to recruit and service union membership in one permanent location , than it is with small specialist ( and more generalist) teams moving from site to site.
Which is how most European buildings are built currently.
Someone should be explaining this to the labour movement.