Environmental Performance of Wood and Wood Products
One of the best bodies of scientific information on the topic of the environmental performance of wood and wood products in the U.S. is research generated by the CORRIM - The Consortium for Research on Renewable Industrial Materials – the go to place for wood-related Life Cycle Assessments. CORRIM has prepared a document, “Integrating Wood into the Circular Economy” for Congressional Committees to defend the environmental performance of wood products. As a CORRIM’s scientific group member, I decided to highlight a few sections of this document and share them with the Woodland Steward readers. The full document and related resources on the environmental performance of wood products could be found on the CORRIM website: www.corrim.org.
CORRIM team are scientists with expertise in forest carbon, wood products, engineering, and architecture that recognize forest management and wood use as an integral component of a coordinated climate mitigation strategy. Nearly 25 years ago, scientists from 20 university forestry research institutions (Purdue among them) formed CORRIM as a scientific research consortium that conducted a rigorous scientific analysis of the environmental performance of wood products using internationally accepted methods, standards, and tools.
CORRIM member institutions and their partners have collectively generated hundreds of peer-reviewed publications and spoken both nationally and internationally on the benefits of using wood as a carbon-negative technology. Federally funded research on the environmental performance of wood products makes a compelling case for the carbon mitigation benefits of using wood in place of more energy-intensive materials and fossil fuels. Together in partnership with the USFS Forest Products Lab, the USFS Pacific Northwest (PNW) Research Station, the U.S. Department of Energy, and other federal labs, CORRIM created a large body of work using data-driven life cycle analysis to quantify and characterize the environmental performance of wood products, including biofuels. Our research has found that wood and wood products, when appropriately deployed, can reduce U.S. greenhouse gas emissions in the built environment, transportation, and manufacturing sectors, with significant co-benefits of sustaining rural economic development and maintaining forests as forests. There is wide variability in the carbon mitigation benefits of wood depending on how and where it is used. Wood demonstrates the most significant climate mitigation potential where it can substitute for more energy-intensive materials like steel and concrete in the built environment, with greater benefits shown in multi-story construction due to lower fossil fuel use in manufacturing and construction with the added benefit of carbon storage in the building itself.
Forests and Wood Products Store Atmospheric Carbon. Wood is about 50% carbon by dry weight, so 1 ton of wood holds 1,000 pounds of carbon, which is equal to 3,667 pounds of carbon dioxide that have been removed from the air. The wood harvested from the forest is used in a wide variety of products, from wooden boards to rayon fabric, paper, food, and more. The harvest residues left in the forest after harvest support biological activity in the next generation of planted or self regenerated trees and contribute to above and below ground soil carbon. Complex supply chains for solid wood, engineered products like fiberboard, paper, and energy, use more than 99% of every harvested log. This nearly zero waste manufacturing sector does produce Green House Gas (GHG) emissions, but over 70% of those emissions come from renewable biomass energy rather than fossil fuels. Taken together, U.S. forests and wood products remove enough carbon dioxide from the air yearly to offset about 11-15% of U.S. fossil fuel combustion emissions. Of that total, about 56% is stored in stable soil carbon, and 5% is held in harvested wood products. When considering only the actively cycling parts of the system – i.e., the trees and harvested wood products – 11% is in harvested wood products. USFS inventory data show that over the past 30 years, carbon stored in forests (live and dead biomass) has increased by 22% and carbon in wood products (in use and in solid waste disposal sites) by 24%, resulting in over 5 billion metric tons of additional carbon stored in the forest sector as a whole since 1990.
Unmanaged Forests are Net Sources of Atmospheric CO2. Not only do the carbon, nitrogen, and methane emissions from wildfires reduce forest sector climate mitigation benefits, they reduce forest inventories, sometimes for decades. In the near term, they also create massive health, safety, and economic impacts in affected communities mainly throughout the west (e.g., California, Oregon, Pacific Northwest) and create critical wildlife habitat and water quality degradation. Federal forest inventory statistics show that some states are already net GHG sources due to the impact of fires and insects.
Facts Support Benefits of Product Substitution. Studies showing that the wood sector offsets 11-15% of the state, regional, or national GHG emissions do not include the carbon mitigation benefit from product substitution. This product substitution benefit is the difference in GHG emissions between alternative product systems that serve the same function. Multiple analyses comparing wood to competing materials (i.e., steel, concrete) show that climate benefits are 0.2-14 times greater when using wood over alternative materials. These differences arise because of the significant differences in manufacturing processes and the GHG emissions associated with them, and the co-benefits of carbon storage in the wood product itself.
Scientific Justification for Considering Wood as a Carbon-negative Technology. While there are no immediate fixes for climate change, there are immediate fixes that can shift society in a direction that reduces GHG emissions. They start with sound forest policies that encourage and support sustainable forest practices by private forest landowners that own 70% of U.S. forests and provide most of the wood products we use – from toilet paper to wooden skyscrapers. It includes a realistic assessment of our building needs and how best to meet them sustainably using American grown products that support rural economies. CORRIM supports and illuminates the scientific connections between healthy, sustainable forests and healthy, sustainable markets for low carbon wood products. In that way, it provides the scientific underpinning for efforts like the Trillion Tree Movement, the US Forest Climate Working Group, and the American Forest Foundation with their direct focus on implementing natural climate solutions that rely on the relationship between a stable forest – economic system. 
Figure 1. Conversation Plinth - one of the first hardwood Cross Laminated Timber structures temporarily build in Columbus, Indiana. It contained locally sourced hardwood lumber. https://bensonwood.com/portfolio/conversation-plinth/
How does the Indiana Hardwood Industry Contribute to these Efforts? The high-quality hardwood forests of Indiana make significant contributions to the environment and economy. Drawing from their abundant hardwood resources, Indiana has ranked the first nationwide in production of wood office furniture, kitchen cabinets, and hardwood veneer. Logs, lumber, and veneer, Indiana’s primary exports of hardwood products, play a dominant role in total hardwood sales, however, they tend to fluctuate with macroeconomic conditions and trade policies. Indiana hardwood market has available wide variety of hardwood species in significant volumes and high quality. Indiana forest products industry is also producing a variety of high-quality, durable hardwood products with a long lifecycle and low environmental footprint. Despite all of that, there is still space to add better value to hardwoods, to find new uses and new markets for this abandoned resource. The Wood Research Laboratory at Purdue University is working on various projects related to value-added hardwoods. Our group is looking for new opportunities to add value to lesser-used wood species, increase production efficiency, implement new technologies, and involve hardwood in the mass timber buildings to develop the Indiana wood product industry further.
Eva Haviarova is a Professor of Wood Products Engineering and Furniture Strength Design in Department of Forestry and Natural Resources at Purdue University. Dr. Haviarova also serves as director of the Wood Research Laboratory (https://www.purdue.edu/woodresearch/). Elaine Oneil, PhD, CORRIM Director of Science and Sustainability, contributed to this document (elaine@corrim.org).