Carbon Storage in Washington's Forests

Growing Carbon

As atmospheric levels rise, how can Washington’s forests turn climate-changing carbon into trees?

written by Daniel O’Neil

Forget gold and platinum. They pale in comparison to carbon. Diamonds are solid carbon. Oil and coal are carbon, too, having originated as vegetation that took carbon from the air hundreds of millions of years ago and stored it as roots, trunks, leaves, algae. But ever since the Industrial Revolution fired up, this carbon has returned to the atmosphere where it now poses existential threats in the form of global warming and climate change.

Washington does not have many gold deposits. It does not produce diamonds, oil or coal. But the Evergreen State does grow trees exceptionally well. Its west side supports some of the most productive forests in the world. These temperate rainforests can extract excess carbon from the sky and store it as towering green for centuries, limiting the damage done by burning fossil fuels. But only if we let them.

Sequestering and storing atmospheric carbon using forests is not a radical idea. The question is why Washington doesn’t embrace the strategy of putting its forests to work capturing carbon while still producing top-quality timber.

A satellite view of Washington helps explain the state’s potential for forest-based decarbonization. When the skies clear between the ocean and the Cascade Range, a rugged, emerald landscape emerges, a stark contrast to the dry, mostly brown expanse east of the Cascades. While Washington’s arid, fire-prone eastern forests do consume, and emit, carbon, the focus of carbon capture and storage resides in the temperate rainforests of the west.

With society worldwide emitting about 40 billion tons of fossil fuel-born carbon dioxide into the atmosphere each year, it’s clear that Washington’s forests alone cannot halt anthropogenic climate change. They can, however, do their part, and they could make a significant contribution toward Washington’s goal to be net-zero in greenhouse gas emissions by 2050.

Dr. Beverly Law, professor emeritus of global change biology at Oregon State University, has spent decades advancing the science on carbon and forests. Western Washington’s forestland is some of the most carbon-rich on the planet, she said. “If you look at the carbon density, the amount of carbon in biomass per unit area of ground is higher than it is in tropical forests. So they’re really important for climate mitigation,” she said.

A study of Washington’s west-side forests by Law and colleagues calculated that these woods currently hold about 826 million metric tons of carbon aboveground in trees, the equivalent of 8.26 million train carloads of coal. If left uncut until 2100, Washington’s forestland would sequester the equivalent of thirty-eight years of the state’s current annual carbon emissions.

Law’s research has also determined that by growing trees for longer on private land, and by protecting more publicly owned forestland from harvest, Washington’s forest carbon stock could double, or even triple, during this century, depending on how much public forestland was set aside.

While a no-cut policy could remove important amounts of carbon from the atmosphere, other interests are also at play in Washington’s woods: lumber and jobs, for example, but also forest resilience in the face of fire, insect, and disease pressures related to climate change. Some experts, concerned by the ballooning amount of carbon in the air and its consequences, believe it’s possible instead to have carbon-storing forests and cut them, too.

Climate-smart forestry proposes a compromise between today’s intensive logging and a scenario in which no trees are cut. It values climate-related issues—like carbon capture, retention of mature and old-growth trees, forest ecosystem resilience, reducing forestry-related emissions, and supporting rural economies—rather than a take-it-or-leave-it-all approach.

When and how a forest is cut determines much of climate-smart forestry. “There’s a ton of science that says if you cut trees at a less frequent cycle, up to a certain age, you can both store more carbon and have more biomass to harvest per acre,” said Dr. Paula Swedeen, senior director of policy for Olympia-based Conservation Northwest, a nonprofit. “Our forests in Western Washington are really strong carbon sinks. Left to their own devices, they would store massive, massive amounts of carbon. So can we utilize the strength of our carbon sinks in these managed lands to store more carbon in the forest while we’re still producing wood products that we all need?”

Our forests in Western Washington are really strong carbon sinks. Left to their own devices, they would store massive, massive amounts of carbon. So can we utilize the strength of our carbon sinks in these managed lands to store more carbon in the forest while we’re still producing wood products that we all need?

As with all topics in forestry, the question of carbon capture potential is debated. In Washington and elsewhere, some foresters believe short rotations—cutting trees young, in thirty-five-year cycles—devour more carbon from the atmosphere than longer, say, eighty-year rotations. Short rotations are preferred by private, industrial timber companies, which own 20 percent of Washington’s total forestland, some of the most biologically productive forests in the state. The financial system in which these firms operate reaps the most return on investment from quick turnover.

Numerous experts disagree. Seth Zuckerman, executive director of the Northwest Natural Resource Group in Seattle, said the data suggests most carbon uptake occurs from around age 30 to age 80, hence the climate-smart logic of longer rotations.

“The shorter your rotation, the longer the time that the forestland spends not being at its peak efficiency of removing carbon from the air,” Zuckerman said. “So you’re basically forfeiting the first five or ten years of your rotation while you, in effect, rebuild your solar panels that are going to pull the carbon out of the air. If you do that on a forty-year rotation, you’re spending a quarter of your time in that rebuilding phase. If you do it on an eighty-year rotation, you’re only spending an eighth of the time in that rebuilding phase, so it stands to reason that you’re not going to be as efficient at carbon sequestration in a short rotation as with a long rotation.”

Computer modeling and other analyses have shown that longer-rotation forestry offers greater carbon sequestration and storage, increased timber volume and other benefits like forest ecosystem resilience and expanded biodiversity and wildlife habitat. The question becomes how to compensate for lost revenue while private landowners extend rotations. Transitioning small increments of land over time, or slowly increasing the rotation time from forty years to fifty years, are two options. Thinning forests, especially the 44 percent of Washington’s forestland owned by the federal government, could also help fill the void while restoring overgrown woods to greater health and complexity.

Across active timberlands in Western Washington, clearcutting—or, in industry terms, regeneration harvest—remains the standard method for harvesting trees. Industrial owners consider the removal of an entire block of forest as the most efficient and therefore economical practice. Washington’s Department of Natural Resources, or DNR, also employs regeneration harvest on the 2 million acres it manages, but to a lesser extent. Besides its consequences for soil, streams and wildlife, clearcutting and forestry in general carry a carbon toll.

Research by Law found that 100 years after harvest, 65 percent of the wood had returned to the atmosphere as carbon, with the remaining carbon divided between landfills and long-lived wood products. “We call it ‘slow in, fast out,’” Law said. “It takes a long time for the carbon to get into the trees to be held there. But when you cut them, a lot of it goes to the atmosphere relatively quickly.”

Logging debris like treetops and branches decompose or are burned, emitting carbon into the air. Mills burn sawdust and scraps for energy and heat, which releases more carbon. Transportation in forestry emits comparatively little. According to Swedeen, up to 40 percent of the harvested wood does not become a product, and wood products themselves decay over time in landfills. The amount of carbon stored in wood products is about 10 percent of the total amount of carbon stored in the forest, she added.

By removing all vegetation and disturbing the forest floor, clearcutting and the large-scale variable retention cuts practiced by DNR account for extra carbon release. Research by Dr. John Talberth, president and senior economist at the Port Townsend-based Center for Sustainable Economy and co-director of the Forest Carbon Coalition, shows that for ten to fifteen years after a clearcut, the forest ecosystem emits more carbon than it captures.

“If you had a different model where you did individual tree selection or patch cuts, what’s called variable density thinning, where you leave the canopy intact, you don’t have those carbon sequestration dead zones,” Talberth said. “That’s where climate-smart forestry comes in. It’s a way to get the wood we need while leaving the forest canopy intact.”

With 10 percent of Washington’s total forestland under its control, DNR works under a mandate to produce revenue from those trust land forests, but also to respect other values, including decarbonization, to meet the state’s emissions goals. In line with election promises, DNR’s new commissioner has paused logging in mature forests to evaluate, among other things, their carbon-capturing ability.

In search of ways for the state’s forests to sequester and store as much carbon as possible, Swedeen and colleagues recently ran some sophisticated computer models using DNR data. She found that by reducing the amount of acres cut, and increasing the amount of thinning, over time DNR could transition from its average fifty-year rotations to seventy- to eighty-year rotations. is method would retain twice as much carbon (in the forest ecosystem and in wood products) while maintaining the same amount of timber volume as harvested today, and create jobs because thinning requires additional labor.

“That’s pretty exciting to me, to know that we could make much more use of the potential carbon sinks that we have in our Western Washington forests than we are now, and we can do it without sacrificing the jobs,” she said. “We’re hoping that DNR would incorporate our findings or take the fact that our findings point in a certain direction when they do their next sustainable harvest calculation, to have an option for increasing rotation lengths on their regular managed lands.”

DNR Uplands Silviculture Program manager Calvin Ohlson-Kiehn believes his agency is already trapping large amounts of carbon. Half of the forestland managed by DNR is protected from harvest, and the agency says the carbon uptake of those forests offsets the emissions from logging on the other 1 million acres.

Ohlson-Kiehn considers DNR forestry one of the most responsible in the world. “We’ve always wanted to maximize volume sustainably, and when you maximize volume, you’re pretty well aligned with maximizing carbon sequestration,” he said. “I do think that in Western Washington there are ways that we could make minor adjustments to our silvicultural practices, like planting slightly different proportions of different species and managing stands at different densities. But in my opinion, we’re probably 80 or 85 percent of the way there.”

A little over 35 percent of Washington’s forestland is privately owned, and more than half of this, some 4.5 million acres, is owned by industrial timber companies who are foremost interested in profit. Private landowners, especially industry, will need to contribute if Washington wants to reach net-zero emissions by 2050.

For decades now the carbon market concept has proposed a financial mechanism for protecting the atmosphere and climate from carbon overload. Emitters of greenhouse gas emissions can buy credits on the market that pay someone else to, among other things, grow trees for carbon capture. Washington has no full-scale carbon market of its own, but its forestland owners now have access to California’s robust version.

While the carbon market offers the financial incentives needed to entice industrial timberland owners, few in Washington are responding. Port Blakely, a timber company based in Seattle, however, has dedicated 10,000 acres in Washington to the carbon market—offsets will pay for longer rotations. Ecotrust Forest Management, a climate-smart investment firm with forestland in Washington, works with the carbon market and has collaborated with companies like Microsoft and Meta to offset emissions by growing forests. (Both timber companies declined to comment for this article.)

One limiting factor of the carbon market is accountability. Fossil fuel emissions are often offset by forests, but timber harvest incurs its own emissions, which are then offset by other working forests—the carbon buck only gets passed. After harvest, landowners can get offset money for replanting on the same site, despite the quantity of carbon released by converting that forest into wood products.

Besides these loopholes, forestry’s own greenhouse gas emissions are not fully calculated in Washington. A recent paper co-authored by Talberth documented that Washington’s emissions from logging would be the number one or number two source in the state if they were properly counted. According to his calculations, DNR-managed lands fall in last place for net carbon sequestration in Washington’s forests, just behind industry.

Once again, forestry experts remain divided. “This is where the science gets complicated and there isn’t perfect agreement,” DNR’s Ohlson-Kiehn said. “When you harvest those wood products, the majority of them go into building materials where they are still sequestered, and then you grow more. Obviously there are some emissions, but essentially we are sequestering so much more carbon than we will ever harvest.”

While DNR forestry is linked to public policy, industrial forestry responds to other, more financial, incentives. Several options exist, including taxation. Talberth and others have proposed the framework for updated tax structures that could bring more industrial timberland owners in line with Washington’s emissions goals.

“If we put a forest carbon tax on the emissions from industrial logging, but give generous exemptions and credits for doing climate-smart practices, that would help catalyze the transition we need on private lands,” Talberth said.

New taxes are an option, albeit a politically challenging one in a state where “Big Timber” maintains a juggernaut presence in policy making. Modifying existing taxes, modernizing them, in a sense, to incentivize climate-smart forestry might be more palatable in Olympia.

Zuckerman proposes changes to the timber tax that is already collected when trees are harvested. “If you wanted to incentivize longer rotations, and incentivize thinning along the way to raising older forests, you could change that structure,” he said. “You could lower the tax rate for those who conduct a partial cut, and you could raise the tax rate on those who do a regeneration cut and have the rate be higher the younger the trees are when you cut them.” Higher taxes on status-quo forestry could also support a rebate for those who thin because of the additional labor required for thinning, he added.

Finally, on one point everyone agrees: Massive wildfires have become a major source of Washington’s carbon emissions in recent years. Agencies and private landowners, especially on the east side of the state, are now engaged in wildfire mitigation efforts to build forests’ resilience. Even on the west side, drought has become a limiting factor in forest health. Both threats are exacerbated by emissions-related climate change. As the climate crisis grows, forests are having an ever harder time helping stop it.

Addressing the emissions and climate emergencies will take a global effort. Washington cannot save the planet, but it can pull more than its fair share of carbon from the atmosphere, and reduce current emissions, by modernizing its forestry practices, taxes and regulations. Just like trees, forestry and policy can evolve and adapt to new situations.

“Right now, in my view, we’re under-encouraging the sequestration of carbon, the stability of rural communities, the production of high-value, high-quality timber products,” Zuckerman said. “There’s a lot of room for improvement. We’re overweighting the short-term production of timber and cash, and undervaluing the forest’s ability to sequester carbon. It’s up to us as a state and as a society to decide what mix of those different possible outputs we want to encourage.”