Trees absorb carbon dioxide from the atmosphere to grow, so forests have long been proposed as a way to offset climate change.
But rather than just letting the forest sit there for a hundred or more years, the amount of carbon dioxide taken out of the atmosphere could be quadrupled in 100 years by harvesting regularly and using the wood in place of steel and concrete that devour fossil fuels during manufacturing, producing carbon dioxide.
"Every time you see a wood building, it's a storehouse of carbon from the forest. When you see steel or concrete, you're seeing the emissions of carbon dioxide that had to go into the atmosphere for those structures to go up," said Bruce Lippke, University of Washington professor emeritus of forests resources. Lippke is lead author of a paper in the June issue of the journal Carbon Management that examines forest management and wood use as they relate to the greenhouse gas carbon dioxide. Co-authors on the paper are from the University of Washington, Mid Sweden University and U.S. Forest Service.
Their review identifies many opportunities to use wood in ways that will displace products that cause a one-way flow of carbon dioxide from fossil fuel emissions to the atmosphere, contributing to the risk of global warming.
Lippke said sustainably managed forests are essentially carbon neutral as they provide an equal, two-way flow of carbon dioxide: the gas that trees absorb while growing eventually goes back to the atmosphere when, for example, a tree falls in the forest and decays, trees burn in a wildfire or a wood cabinet goes to a landfill and rots.
The co-authors write that the best approach for reducing carbon emissions involves growing wood as fast as possible, harvesting before tree growth begins to taper off and using the wood in place of products that are most fossil-fuel intensive, or even using woody biomass to produce biofuels for use in place of fossil fuels.
The authors aren't advocating that all forests be harvested in this way, just the ones we particularly want to use to help counter the buildup of carbon dioxide in the atmosphere. Older forests provide many needed ecological values although their ability to absorb carbon dioxide slows down.
"While the carbon in the wood stored in forests is substantial, like any garden, forests have limited capacity to absorb carbon from the atmosphere as they age," Lippke said. "And there's always a chance a fire will sweep through a mature forest, immediately releasing the carbon dioxide in the trees back to the atmosphere.
"However, like harvesting a garden sustainably, we can use the wood grown in our forests for products and biofuels to displace the use of fossil-intensive products and fuels like steel, concrete, coal and oil."