Malheur National Forest in Oregon. Courtesy USFS.
You know about the contributions deforestation makes toward global warming, but now some scientists are asking the seemingly counter-intuitive question of whether harvesting timber can actually help decrease greenhouse gas emissions.
No doubt, the premise is appealing: Use the forests to soak up carbon dioxide from the air, then store that carbon dioxide elsewhere by harvesting the timber and turning it into home-building materials and other wood products. As new trees grow in the harvested area, the cycle begins again.
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Some have held out hope that this strategy could supplement other larger climate mitigation tactics, but a recent report from The Wilderness Society shows the harvesting strategy would likely do more harm than good.
In the long run wood products experience too many processing losses of carbon, and require too much energy, to be a practical way to store carbon, said author of the report Wilderness Society resource economist Ann Ingerson.
According to her report, Wood Products and Carbon Storage: Can Increased Production Help Solve the Climate Crisis?, a large amount of carbon is lost during the harvesting and processing of wood, but beyond that, once the wood is processed, the carbon does not remain locked away but is released through decomposition over time.
Significant losses of carbon occur upon harvesting alone. According to the report, losses at the harvest site may average as much as 59 percent of carbon in the live tree for some states, while further processing and use of the wood products result in more losses.
In fact, as little as 1 percent of the carbon present in a standing tree may remain in solid wood products 100 years after the trees are cut, the report says, with a larger amount remaining in landfills.
Ingerson explains that once you factor in the energy and fossil fuel emissions from processing the wood and the fact that forests don’t always immediately replace what has been lost, the harvesting has little benefit for global warming mitigation and could actually have negative impacts.
“If you’re looking to store carbon, the very best way to do it is to keep forests as forests, and then keep those forests consistently growing trees, year-in and year-out,” Ingerson said.
She explained that careful harvesting can be consistent with this goal, but there is ultimately a trade-off between intensity of harvest and the total amount of carbon stored.
Ingerson’s study also looks at the role of wood products in forest-carbon offsets in voluntary or regulatory programs. This is significant because if offsets are expected to balance emissions from polluters, it is important to have a true understanding of the potential for carbon sequestration.
Ingerson explained that while the report could help assist with understanding the challenges in using wood products for climate mitigation, policy makers’ real focus should be aimed at larger mitigation tasks, specifically transforming the nation’s economy from one based on inexpensive fossil energy to truly sustainable, renewable energy.
She said the wood products industry can contribute by increasing its own processing efficiency, reducing its energy use, extending product life, reusing and recycling wood materials, and promoting wood energy that is clean, efficient, and based on sound forest practices.
photo: Malheur National Forest in Oregon. Courtesy USFS.