On August 30, the Potsdam Institute for Climate Impact Research published a study in the journal Nature Communications that claims building future cities from engineered wood products could prevent 106 billion tons of carbon dioxide from entering the Earth’s atmosphere by 2100. As the world’s population increases, more people will gravitate toward cities. Low rise wooden buildings of between 4 and 12 stories could provide shelter for all those people and locations for community businesses without the carbon emissions associated with making buildings out of concrete and steel. Here’s the introduction to the study:
“Here we assess the global and regional impacts of increased demand for engineered wood on land use and associated CO2 emissions until 2100 using an open-source land system model. We show that if 90% of the new urban population would be housed in newly built urban mid-rise buildings with wooden constructions, 106 gigatons of additional CO2 could be saved by 2100. Forest plantations would need to expand by up to 149 million hectares by 2100 and harvests from unprotected natural forests would increase. Our results indicate that expansion of timber plantations for wooden buildings is possible without major repercussions on agricultural production. Strong governance and careful planning are required to ensure a sustainable transition to timber cities even if frontier forests and biodiversity hot spots are protected.
“In 2020, more than half of the global population lived in cities. According to the Shared Socioeconomic Pathway 2 scenario, the global share of the population living in urban areas could rise to 80% by 2100. By the middle of this century, the newly built infrastructure (including new urban housing) may exceed the infrastructure being built since the beginning of industrialization. Conventional buildings today are mostly built using steel and cement. Production of traditional building materials causes substantial anthropogenic CO2 emissions (e.g., due to carbonate calcination, electricity use, and fuel consumption from cement and steel production).
“In 2020, raw material production for conventional buildings caused roughly 10% of the global greenhouse gas emissions, stemming from cement (1.48 gigatons) as well as iron and steel (3.55 gigatons) production. Continuous use of conventional building materials for future infrastructure development could claim 35–60% of the remaining carbon budget associated with limiting the global temperature increase to below 2 °C.
“Using engineered wood for constructing buildings can help to avoid emissions associated with conventional building materials. Wood is a renewable resource that usually carries the lowest carbon footprint of any comparable, first-time use building material. Moreover, the carbon stored in wood, which was absorbed from atmospheric CO2 via photosynthesis, is partly preserved when the wood is used as a building material, making it a long term carbon sink.”
Abhijeet Mishra, the paper’s lead author, tells The Guardian, “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 stories — made out of wood.”
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.” About 15 billion trees are harvested globally each year.
Not Everyone Agrees
Sini Eräjää, leader of the European food and forests campaign for Greenpeace, tells The Guardian that cutting down natural forests and replacing them with wood plantations would be a “terrible idea. 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.”
Abhilash Panda, the deputy chief of partnerships at the UN Office for Disaster Risk Reduction in Geneva, tells The Guardian, ”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.”
What About Fires & Earthquakes?
The thought of wooden buildings gives some people shudders. Won’t they collapse in an earthquake or catch fire easily? The answer is no, they won’t. Modern engineered timbers are as strong as steel and almost as fireproof.
“Future construction of buildings with engineered wood is usually touted as a novel climate change mitigation option,” the study says. “It could reduce GHG emissions from the building sector while reducing the costs related to overall construction. Use of engineered wood in buildings is already associated with fire and earthquake resistance, lower construction times, and reduced waste during construction. The building sector offers a unique opportunity for decarbonization. Substituting a major portion of raw material needed for residential building construction for new urban population with engineered wood provides a lucrative option for long term carbon storage in buildings.”
The Takeaway On Wooden Buildings
The Potsdam study acknowledges that there are opportunities for further research into how to use more wooden buildings for homes and medium rise commercial buildings. It also acknowledges the challenges associated with deciding how to manage the world’s forests to preserve biodiversity. There is no single answer to those questions. But the study opens a pathway for further exploration into how best to provide shelter for an expanding global population without busting the Earth’s carbon budget.
New technologies are making low or zero carbon steel and cement possible, two promising developments that will lower the carbon impact of new buildings and, of course, the new Potsdam study does not consider how those advances may impact carbon emissions from the construction industry. What it does do is show how engineered timber products could benefit the environment if used to build low and medium rise structures.
Wooden buildings are another tool that is available to lower carbon emissions significantly. They should be given due consideration along with all other strategies available to tame the rampant increase in carbon emissions that threaten us all with an environment that no longer supports human life.
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