Unleashing trees in the battle against climate change
Unleashing trees in the battle against climate change
In discussions around climate change and natural resources, one widely mentioned oversimplification is that "cutting trees is bad for the environment." While true that global forest loss has environmental implications, sustainably managed working forests can provide impressive climate benefits in both carbon sequestration and long-term carbon storage.
Last year's Paris Agreement of the 2015 UNFCCC Conference of the Parties (COP) highlights standing forests as part of a strategy to limit global warming to 2 degrees Celsius. This is important, given that tropical deforestation is one the main sources of emissions and is coupled with other climate, biodiversity and human welfare concerns.
However, issues related to forests vary dramatically by geographic region. For example, international timber from illegal sources can contribute to overall deforestation, particularly in weakly managed areas. On the other hand, the United States has not experienced (PDF) net deforestation in decades and has a robust and transparent National Forest Inventory and Assessment Program managed by the U.S. Forest Service.
In fact, U.S. forests and related wood products serve as a substantial carbon sink — the equivalent of roughly 16 percent of U.S. fossil emissions annually (PDF) — partially by storing more than 14.8 million tons of carbon per year in wood products (PDF) made from harvested trees.
Silviculture Magazine has identified three main features of working forests (defined as land already converted to rotating harvest or plantation forests): Timber production; multiple use lands (including habitat and recreation); and sustainability as an "over-arching goal and strategy." Such working forests can be key contributors to climate change mitigation in two primary ways:
Carbon sequestration as a part of climate change mitigation; and
Wood products as a sustainable renewable resource.
Working forests and carbon sequestration
Working (or "managed") forests absorb large amounts of carbon because selective harvesting encourages and maintains rapid growth. Whereas untouched forests eventually will reach a point of "carbon saturation" without natural disturbance (where carbon absorption slows because (PDF) the forest is holding near maximum levels of carbon), sustainably managed forests absorb carbon at more aggressive rates.
For example, a 2000 study published in Tree Physiology found that forests with 10-20 percent of woody biomass harvested annually produced both high timber yields and high carbon storage. In 2013, the Consortium for Research on Renewable Industrial Materials (CORRIM) estimated that a managed forest sequesters an additional 2.6 metric tons CO2/hectare/year (PDF) when accounting for wood products.
Carbon in construction
Well-managed working forests are sustainable, renewable natural resources that provide a climate advantage when used in longer-term wood applications such as construction (for example, beams, planks, particleboard and blown fiber).
Engineered wood products such as Cross Laminated Timber (CLT) are attracting attention because it can replace emission-intensive materials such as steel or cement. For example, the University of Washington West Campus Student Housing project stored 4,466 metric tons of CO2 in wood materials, including engineered materials, in a five-building dormitory complex.
Further, increasing the use of timber in buildings, bridges or other infrastructure also results in a "substitution effect" (PDF) — avoiding emissions that would have been created by materials such as steel or cement. While the strength of the substitution effect varies, one international study estimates that every 1 ton of wood used in construction avoids an average of 3.9 tons of CO2. A 2015 study found 30 percent more total carbon sequestration benefits over equal time from harvested and regenerated forests than forests left to grow, with more than half of those benefits coming from the substitution effect.
Linking wood use and climate targets
To reach global climate change goals, sustainable forest use must be accompanied with an overall reduction in global deforestation.
One important consideration is reducing degradation from overharvesting or transitioning natural forests to plantation land. Policies should be careful not to encourage conversion of natural forests to plantations, as natural forests generally store more carbon (PDF) overall.
Further, shifting away from natural forests results in other negative impacts such as biodiversity loss and diminished water filtration, nutrient cycling and soil control. Environmental considerations for wood products must aim achieve an optimal balance between these environmental services.
Also important is the need for a multi-level, interdisciplinary understanding of sustainable land management and harvest to achieve green growth and climate change mitigation. Academic institutions can help by sharing knowledge and facilitating communication. Business is central and should encourage continued development of their sustainability teams, as some large industry actors, such as Weyerhaeuser and International Paper, are doing.
What does it mean for business?
Working forests produce timber products that can reduce overall pollution, boost local economies, create safer materials, reduce emissions and contribute to a green economy.
For business, emerging climate policies and public opinion on sustainability are creating opportunities to rethink how timber is used and valued. These opportunities extend beyond timber-related industries and reach into architecture, planning and construction disciplines. However, education, cross-industry connections and public relations efforts are required to catalyze such linkages into action.
The biggest challenge today is in connecting the science, business and policy elements to ensure clear wins for business, consumers and the environment. In upcoming decades, the forest industry will see new market opportunities and leverage points in the center of climate policy discussions.
To be prepared, the time to explore the relationship between forests, business and climate is now.