At the University of Washington, we recognize the value of the productive forests and other ecosystems of the Pacific Northwest in contributing to a comprehensive effort to address global climate change. At the UW School of Environmental and Forest Sciences (SEFS), we are working with others in the College of the Environment and elsewhere in the University of Washington to coordinate our education, research, and community engagement efforts related to climate mitigation through carbon storage and sequestration.
Carbon Mitigation & Sequestration
Because of its effects in trapping heat in the atmosphere, carbon dioxide is well-known as a greenhouse gas that is produced in the burning of fossil fuels. Carbon mitigation is any effort made to keep carbon from entering the Earth’s atmosphere or to remove it once it’s there. One form of mitigation is managing active “carbon sinks” resulting in net carbon sequestration, the process by which carbon dioxide is captured and stored for long periods of time.
Carbon, as a basic building block of life, can be trapped and stored in natural features all around us, like trees, soil, and the sediment in bodies of water. Even the wood that frames our houses stores carbon and can contribute to sequestration in the built environment. Annually, U.S. forests take up carbon at a rate equivalent to about 10-20 percent of the country’s fossil fuel emissions each year, according to the U.S. Forest Service. However, as land is developed for other uses, forest productivity declines, or forests are managed unsustainably, the ability for those forests to remove and store atmospheric carbon is reduced. Because these processes involve complex interactions between society and the environment, it’s important that policy makers and forest managers have the best available scientific information about the options for managing for sequestration. SEFS works with a variety of external collaborators and partners to develop, synthesize, and disseminate knowledge that is needed to develop climate change mitigation tactics and strategies.
To explore the relative importance of different strategies for achieving a carbon-negative society in the Pacific Northwest, SEFS Professor Josh Lawler ran a seminar with a group of graduate students in 2020. He plans to build on this work, which adopts the methods of Project Drawdown, by developing a regional assessment and ranking of the key steps that can be taken. In addition to students, this work is in collaboration with SEFS Professor of the Practice Phil Levin, who is appointed jointly with The Nature Conservancy, an organization whose conservation efforts aim to implement Natural Climate Solutions, of which forest-based sequestration is a key part. In order to address social aspects of sustainable solutions, SEFS researchers are also analyzing solutions that aim to store more carbon in terms of the impacts of these solutions on social equity and justice.
Carbon Management Science at SEFS
How much can our forests and forest products contribute to a carbon neutral or carbon negative society? How do we monitor and measure how we are doing with forest carbon sequestration? What are the biggest uncertainties and risks associated with forest carbon sequestration?
SEFS is on a mission to collaborate and contribute to finding the answers to these questions. In 2019, researchers at SEFS and in partner organizations came together to discuss their work and the possible answers.
Where and how is loss of forests reducing sequestration potential?
Old-growth forests, critical habitat areas, and riparian buffers all have some form of protection in Washington State, as do state and national parks, meaning that the amount of carbon that can be removed from them is limited. Working forests are an important part of Washington’s economy and involve harvesting trees that are then regrown. Private forest owners control about one-third of all forestland in Washington State. These owners make decisions about whether or not to keep these lands in forest or convert them to some other use, thereby often reducing carbon sequestration potential.
SEFS researcher Luke Rogers has led efforts to inventory and map the patterns of ownership on these private forestlands over the last couple of decades to understand shifts among owners and risks of conversion out of forest. With support from the Washington State Legislature, Rogers together with SEFS Associate Professor Sergey Rabatyagov, are analyzing the economic, regulatory, and tax pressures these land owners face in Washington State while also considering ways the state can help them keep these private forests as forestlands.
How do forest disturbances affect carbon storage?
Forest disturbances, like wildfires, drought, insects and disease, are natural occurrences in forested ecosystems. How do these disturbances affect the fate of carbon? While carbon can be stored in trees and soil long after they have been burned by wildfire or destroyed by insects, the process of decay slowly releases that carbon to the atmosphere. SEFS researchers are interested in better understanding how the frequency and severity of disturbance, and the rate at which forests regenerate after them affect carbon storage.
Two of the forest management practices that can be used to reduce fire severity are forest thinning and prescribed burns. SEFS Associate Professor David Butman and Professor Jonathan Bakker were curious what impact these practices have on forest carbon. Working with a group of students on a review of literature, they found that thinning ultimately reduces the amount of carbon stored in forests. However, because these practices can reduce fire risk, they can have the effect of increasing carbon storage in the long run, setting up a potential trade-off between short and long-term thinking about carbon storage and fire management.
How do harvested forest products affect carbon sequestration?
While consumptive use of forest products ultimately releases forest carbon back into the atmosphere, forests are a renewable resource, taking up carbon after trees are harvested and replanted. SEFS researchers have found that harvesting forest products can help reduce atmospheric carbon in two ways: through storage in long-term products, like building materials, and through the displacement of materials, like fossil fuels and concrete, that result in much higher emissions. The challenge for researchers is to find the right mix of carbon storage in trees and in products that account for the growth of the trees and the life of the products.
A number of SEFS researchers are collaborating with the objective of creating pathways toward a stronger bioeconomy – that is, the parts of the economy that use renewable biological resources from the land and sea to produce food, materials and energy – that strikes the right balance with use of renewable forest products and leads to greater carbon mitigation. New pathways being conceived by researchers in the Bioresource Sciences and Engineering (BSE) program include products that can replace plastics with bioplastic made from residual softwood biomass, energy pellets made from residual wood, and the use of nanotechnology to develop biomass fire retardants to replace the toxic chemicals often used to fight wildfires. SEFS Professor Richard Gustafson and Professor Renata Bura are looking at how the creation of liquid fuels and other chemicals from biomass, including fast-growing trees and forest residue, can replace fossil fuel-based products.
SEFS Associate Professor and CINTRAFOR Associate Director Indroneil Ganguly is working with researchers at UW’s Carbon Leadership Forum to study the impacts of long-term storage in wood products that displaces concrete and steel in construction. Newly engineered wood products, like cross-laminated timber (CLT) can replace the concrete and steel typically used for building construction. CLT not only stores carbon itself, but its use eliminates the greenhouse gases released into the atmosphere when steel is produced.
“When we take the wood out of the forest, we are planting new forest and sequestering new carbon,” Ganguly told the Seattle Times in 2019. Building with timber is “almost like multiplying acres of the forest.”
Can we manage forests to increase carbon storage?
How we manage working forests can have a large impact on how much carbon they store. There are a number of variables that can affect carbon storage in forests, but rotation length, or how old the trees are before they are harvested, is probably the most important.
SEFS Ph.D. student David Diaz, working with SEFS Associate Professor Greg Ettl, has modeled impacts on carbon storage of sustainable forest management practices in Oregon and Washington forests. Their work has shown that the typical rotation length of 30-40 years on private forests in Western Washington could be lengthened to something like 60-70 years to increase both carbon storage and the volume of timber produced. Forests are typically harvested when they are young because that is when they turn the most profit. This suggests an opportunity to design policies that might compensate landowners for longer rotation lengths to achieve the public goal of increased carbon storage.
Does carbon left in the forest stay there?
If we leave carbon in the forest, it doesn’t just stay put. In addition to decomposition of biomass and soil releasing carbon to the atmosphere, some of it is exported into streams, wetlands, the ocean, and lakes. There, it is either stored or released back into the atmosphere. David Butman works on research with funding from the U.S. Geological Survey and NASA, looking at where carbon goes once it enters streams and rivers in the Pacific Northwest and the Boreal Arctic located in northern Canada.
Carbon accumulation in the atmosphere over the last 150 years has been largely driven by human actions. Efforts to reduce or reverse the effects of the resulting climate changes will require additional concerted human actions. Efforts to increase carbon storage on land and in forest products, and to displace fossil fuels with bio-based fuels, play important roles in those efforts. SEFS is committed to collaborating with University of Washington and state, national, and international partners to generate and communicate the science-based information that is needed to inform wise policy and management decisions toward that end.