Forests, carbon and climate change

Increasing amounts of carbon dioxide in the atmosphere, mostly from humans burning fossil fuels, are contributing to global warming and climate change. This rise in the average temperature of the land and water on Earth has contributed to melting glaciers, rising sea levels, and longer and more intense wildfire seasons, among other environmental impacts.

What does this have to do with forests? It turns out the plants and trees in forests, and the wood products that come from them, can help fight climate change. Trees are great at pulling atmospheric carbon out of the air. The best part is that carbon stays locked up long after a tree is used to make buildings, furniture or hundreds of other wood products.

It starts with photosynthesis

Forest carbon sequestration starts with photosynthesis, the process plants use to take carbon dioxide out of the atmosphere. Chloroplasts inside leaves and needles use carbon dioxide from the air, water from the soil, and energy from sunlight to produce glucose, a simple sugar. Trees use glucose to make wood, storing carbon in the process. Oxygen is released into the atmosphere as a byproduct.

This simplified chemical equation shows how carbon atoms from the carbon dioxide molecules are moved to glucose molecules through the process of photosynthesis:

Carbon in Oregon's forests

 Carbon isn’t stored only in trees; it’s also distributed throughout the forest in carbon “pools.” These include:

How much carbon is stored in Oregon's forests?

With the help of measurements taken in the field, scientists can estimate the amount of carbon physically present in Oregon’s forests per pool — such as the amount of carbon stored in live trees. Total forest carbon is the sum of the carbon stored in all a forest’s carbon pools.

Carbon can move between various forest pools and eventually be released back into the atmosphere, in a process known as “carbon flux.” That means that although forests amass large quantities of carbon as trees grow, they don’t store carbon indefinitely. When trees die and start to decay, for instance, they release carbon. 

The most current estimate of how much carbon is stored in Oregon’s forests are based on forest monitoring conducted by the U.S. Forest Service’s Forest Inventory and Analysis (FIA) program in partnership with the Oregon Department of Forestry. 

Based on the FIA monitoring data from the 2011-2020 inventory period, Oregon’s forests store approximately 3.2 billion metric tons of carbon across all carbon pools on both public and privately owned forestlands.

There is a close relationship between the proportion of Oregon forestland that falls under each type of ownership and how much carbon is stored there. For instance, the national forests, which are managed by the U.S. Forest Service and account for just under half of Oregon’s forestlands, are storing slightly more than half the state’s forest carbon.

There is a close relationship between the proportion of Oregon forestland that falls under each type of ownership and how much carbon is stored there. For instance, the national forests, which are managed by the U.S. Forest Service and account for just under half of Oregon’s forestlands, are storing slightly more than half the state’s forest carbon.

Maximizing forests' carbon-storing potential

Scientists around the world have been studying the role forests can play in mitigating climate change. The Intergovernmental Panel on Climate Change, a United Nations body responsible for assessing international science related to climate change, has recognized the importance of using sustainable forest management practices that enhance forests’ natural abilities to sequester carbon, as well as increasing use of wood products to help reduce carbon dioxide emissions.

Given the capacity of forests to capture and store carbon in the ecosystem and wood products, the timber industry is frequently discussed as a critical component of reducing atmospheric carbon. And Oregon — with its abundant, fast-growing forests and status as the top U.S. producer of softwood lumber — is well situated to contribute.

Oregon’s forests already sequester and store significant amounts of carbon, but there are a number of ways forest landowners and managers can ensure forests can continue to contribute to reducing atmospheric carbon. These include ensuring forestland isn’t converted to other uses, such as housing or other urban development, as well as decreasing the risk of high-severity wildfires and insect or disease outbreaks that can kill large numbers of trees. 

Planting trees to create more forests would help take even more carbon dioxide out of the atmosphere. Active forest management aimed at improving a forest’s overall health and productivity, as well as resilience to wildfires, can help it capture and store greater amounts of atmospheric carbon. Letting trees grow to their peak carbon-storage age before harvest can also increase the carbon stored in existing forests and forest products, although there are financial trade-offs with this strategy for landowners who primarily manage their forests for timber production.

Retaining forests is important to fighting climate change

Forests in the United States serve as a “carbon sink,” offsetting approximately 10%-15% of the country’s carbon emissions from burning fossil fuels each year, according to the U.S. Forest Service. This underscores the crucial role of forests in capturing and storing atmospheric carbon into the future.

The significant conversion of forestland to agriculture and urbanization — particularly rainforests in tropical regions — has affected our climate. Fortunately, Oregon has done remarkably well in protecting forests from development. 

One reason the amount of forestland in Oregon has remained steady is that many private landowners have an economic incentive to preserve forests for timber production. This means they’re less likely to sell forestland for development into housing or other uses. 

Landowners are also required by Oregon law to replant trees after a timber harvest, ensuring these forests will remain forests.

Using wood reduces carbon footprints

Carbon storage is one reason wood is a more environmentally friendly building material than concrete or steel, which require more energy and water to produce and emit large amounts of carbon dioxide during the manufacturing process.

Wood performs well in life cycle assessments (LCAs), a method of tracking the overall environmental impact of a product — from the extraction of the raw materials used to make it, through to the product’s disposal. LCAs have shown that the manufacturing of wood products typically consumes far less water and requires far less energy, and therefore generates fewer carbon emissions, than producing other construction materials. For Pacific Northwest mills, most of the energy they use to make wood products often also comes from renewable sources, primarily from using wood residuals from the milling process to generate biomass energy. 

As a result, timber construction reduces the overall carbon footprint of a building project, both through carbon storage and by substituting wood for more energy-intensive materials. 

Learn more by reading:

Carbon in Oregon’s Managed Forests – Summary Report (2020)

Carbon in Oregon’s Managed Forests – Science Review on Carbon, Managed Forests and Wood Products (2020)