Conservationists hit out at idea of 'timber towns' and more forest plantations

The proposition is set out in a paper entitled ‘Land use change and carbon emissions of a transformation to timber cities’, authored by Abhijeet Mishra et al at the Potsdam Institute for Climate Impact Research (PIK). It was published in Nature Communications 13, Article No 4889 (2022). Irrespective of its merits, the immediate reaction shows the difficulties in balancing differing views of commercial forestry and the timber industry with those of the wider environmental lobby.

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The premise on which the proposition is based is that construction of new homes from wood instead of concrete and steel could save some 10 per cent of the carbon budget required to keep temperature rises from global warming to 2°C this century. In numbers terms, housing 90 per cent of the world’s urban population in ‘mid-rise’ timber-built homes would avoid 106 billion tonnes of carbon emissions otherwise generated by the end of this century. Land-use changes required to effect such a change would require 149 million extra hectares of forest timber plantation by 2100, as well as the redirection of a large proportion of the existing timber harvest, says the report, without impacting on productive farming.

Lead author Abhijeet Mishra told the press: “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.”

This study is said to be the first to analyse the potential for cuts in carbon emissions by switching from steel/concrete to timber construction on such a massive scale.

The PIK researchers used the ‘Magpie Open Source Global Land Use’ model to explore the likely impacts and the practicalities of constructing cities made of wood. The reasoning behind the research is that wood has the lowest carbon footprint of all building materials. Commercial materials that is, because straw, dried grass, palm fronds and reeds etc, commonly used by village communities around the world, may come in with a lower carbon footprint than wood. 

Co-author Alexander Popp said preventing logging for timber in pristine forests and biodiversity conservation areas was crucial to their calculations, but conservationists were clearly not convinced, reasoning that if productive farming would be unaffected then natural and semi-natural forests would suffer accordingly. 

I guess it was the numbers which spooked them, because an extra 149 million hectares of commercial forest plantation is the equivalent of the combined total land area of Germany, France, Spain, Portugal, Italy, the Netherlands and Belgium. That’s larger than the 131 million hectares of existing forest plantation around the world which is claimed to be less biodiverse than natural forest and woodland and more at risk of destruction by fire.

The Guardian was the first in the mainstream media to run with the story and the environmentalists they spoke to did not hold back. Sini Eräjää, Greenpeace’s European food and forests campaign lead, told how it would be “a terrible idea” to cut down natural forests and replace them with forest timber plantations. 

She said: “It would be a disaster for nature and for the climate. 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.”

Abhijeet Mishra accepted wildlife loss would occur with forest timber plantations, compared with natural forest, but said “strong governance and careful planning to limit negative impacts to biodiversity” were required. “Bio-physical risks” such as the potential for city wildfires to become more common had not been assessed in the report, he said.

Timber is still the preference for house building in many countries including Nordic nations, the United States and Japan, although the recent spate of wildfires, which are expected to increase as climate warming intensifies, has led many construction experts to question building using flammable materials.