A new report from an international team of scientists concludes that managing forests better and using engineered wood products to build tall buildings in urban areas could have a major effect in preventing damaging climate change. (Buildings as a global carbon sink, Churkina, et al https://www.nature.com/articles/s41893-019-0462-4). Experts from Yale University, Potsdam Institute for Climate Impact Research and Tsinghau University analyzed how much new construction will be needed to accommodate the expected increase in urban dwellers over the next 20 years—another 2.3 billion city dwellers worldwide. They determined that just creating that many buildings using concrete and steel would use up 60 percent of the remaining carbon budget available if the world wants to keep temperatures from exceeding 2 degrees Celsius. That doesn’t allow enough room in the carbon budget for transport, heating and cooling buildings, and raising food. Put another way, if we continue to build with steel and concrete, we will cook the planet. Wood from sustainably managed forests, manufactured into engineered wood building components that are as strong as steel and concrete, can substitute for steel and concrete and so avoid the problem.

The authors suggest an alternative future for buildings:

“In a few decades, a material revolution, scaled in its application to global urbanization and to the sustainable capacities of its forest sources, may balance material supply, material demand and environmental burdens and benefits while answering the challenge of urgent climate action.”

The report identified three areas of potential carbon savings and offered estimates for two of them. The first offset involves reducing the manufacture and use of steel and concrete, avoiding carbon pollution from the manufacturing process. Although wood production also uses fossil fuels to transport timber and saw it into lumber, the amount of pollution is far smaller than that required for steel and concrete manufacture, as both materials require heating to above 2,500 degrees. The authors estimate that as much as 36 gigatons of carbon dioxide emissions might be avoided if we made a strong transition to wood buildings, equivalent to reducing current emissions by nearly 4 percent.

A second form of climate mitigation occurs when trees remove carbon from the atmosphere and that carbon is captured in the engineered wood products within the buildings for long periods of time. The more buildings constructed out of wood, the more carbon is sequestered. In a way, it is like creating another global forest in our urban areas. The potential is there to sequester 9 percent of the total existing carbon in our forests by creating a new kind of urban forest over the next thirty years. This could result in sequestering as much as 73 gigatons of carbon dioxide in new buildings—which represents carbon dioxide locked safely away.

The third area of potential carbon savings is tied to the pool of carbon now stored within the forests of the world. Depending on how the forests are managed to deliver the construction materials, the in-forest carbon can increase or decrease over the next 30 years. The authors did not analyze this effect but did conclude there are pathways of forest management that could produce a positive climate effect. They noted that 43 out of 65 evaluated countries now harvest less wood than they grow. However, they warn that a precondition for achieving higher harvest levels and maintaining carbon storage in-forest is preserving forest sustainability and continuing re-forestation efforts as well as leaving biologically valuable or vulnerable forests in reserve. They authors offered no predictions for carbon savings or losses for this category.

This is where New England Forestry Foundation (NEFF) can provide some useful additional information. NEFF has analyzed the potential effects of improved forest management in New England forests. We started by codifying our 76 years of forest management experience into a set of climate-smart forestry practices called Exemplary Forestry standards. These standards are written for northern New England forests, and they aim to ensure that in-forest carbon is maintained or increased during the next 30 years. We then analyzed how much additional carbon dioxide could be removed from the atmosphere and stored in trees if these forest practices were applied across Vermont, New Hampshire and Maine. The impact is significant: Just in northern New England we could store an additional 1.9 gigatons of carbon dioxide in the forest—the carbon equivalent of taking every vehicle in New England off the road for more than 20 years. This potential was featured in a New York Times op-ed: https://www.nytimes.com/2019/10/03/opinion/wood-buildings-architecture-cities.html

Our next round of research will combine the three areas of carbon savings in one hypothetical scenario—the creation of a five-story wood building in Boston from sustainably managed woodlands in western Massachusetts. This will allow policy-makers to consider the full suite of benefits from mass timber construction. Over time, we’ll extend this research by identifying Exemplary Forestry standards for all New England forest types, calculating the wood building potential in New England urban areas, and modeling the overall climate mitigation effect from improved management of New England forests and building with wood in urban areas. Our work is directed toward proving the potential right here in New England for applying the global case made by these authors.  

NEFF’s forestry expertise lets us answer questions regarding in-forest effects not included in this new study. Our research proves that improved forest management can increase growth in the forest two- to three-fold over current rates. And our best productivity comes from heavily stocked forest stands that store more carbon than is typical in the region. This historical knowledge of how forests respond to exemplary management gives us confidence New England forests can produce the material necessary for a revolution in urban construction while increasing carbon storage in the forest as well. With the right cooperation of landowners, foresters, mill owners, architects, builders and policy makers we can find a Forest-to-Cities solution and make a major contribution to fighting damaging climate change right here in New England.

Photo: Rhode Island School of Design’s North Hall, the first cross-laminated timber-steel hybrid residence hall in New England. Photo by John Horner, courtesy of RISD.