Using Timber for Energy, Buildings, and Furniture – the Myth That Cutting Trees Is Bad for Climate Change
Figure 1 – Carbon cycles
Charles Levesque
This is the second and final article in a series of exclusive Green Energy Times articles on some myths about climate change and the role trees and forests play in mitigating climate change’s effects.
In the first article on forest carbon in the June 2022 issue of G.E.T., we discussed why not cutting trees in the northeast, where abundant forests are located, is not the best choice for addressing climate change. We talked about carbon sequestration – the act of trees taking in atmospheric carbon as part of photosynthesis. And we discussed carbon storage in forests. Younger forests sequester more carbon per acre as compared to older forests. And older forests store more carbon per acre than young forests. This carbon represents carbon sequestration in the past.
And we also discussed the fact that if we don’t harvest trees in the northeast where we have abundant timber – the most forested region in the U.S. and our forests are growing way more annually than we are harvesting. That uncut timber will be harvested somewhere else, because annual use of timber for all purposes is increasing year after year here, the U.S. and worldwide.
Wood for Energy
Using wood for energy has been somewhat controversial in the northeast in recent years. Some people who don’t want to see trees cut say we should burn fossil fuels for energy instead of wood because they are more energy-dense than wood. The problem with that thinking is that fossil-fuel burning is the main cause of human-induced climate change. Doing so brings geologic carbon from deep in the earth and releases it to the atmosphere for the first time, adding to what is already there. Using wood for energy is much more carbon and climate-friendly because it is within the biogenic cycle (Figure 1) where the carbon released from burning wood is then sequestered again by trees – and the cycle can continue over and over again without a net increase in the atmosphere as long as we are growing more wood and carbon than we are using. This is what we do in the northeast.
And burning it more efficiently, in modern wood heating appliances like woodstoves with catalytic converters and high efficiency firewood, wood pellet and woodchip boilers and furnaces, is essential to getting the most energy out of every cord of wood.
Timber as a Climate-Friendly Building Material
We have over 50 million acres of forest in the northeast region that includes the seven states of New England, and New York. That’s a lot of trees. Annually these forests, owned mostly by private individuals, families and companies, and some in public ownership, grow nearly twice the amount of timber removed from harvesting and land-use change. That means that the standing inventory of timber (and thus carbon since wood is half carbon) goes up every year, and this has been going on every year since the USDA Forest Service started keeping track of this data in the 1950s. Forest carbon in the region’s forests has increased by 15% just since the year 2000! (Figure 2)
Figure 2 – USDA Forest Service, Evalidator 2.0.3
But because these forests are growing bigger and older over time, the annual sequestration rate – the amount of carbon sequestered per acre every year – has actually decreased over time. Younger forests sequester more per area than older forests. If you were standing in a forest where most of the trees are about six to eight inches in diameter, that would be the age forest that is sequestering the most carbon each year. Older forests, however, store more carbon per area because the trees are bigger.
An added benefit in the northeast U.S. is that when we harvest trees here – just a small portion of what grows each year – we are blessed because they grow back naturally – we don’t have to plant them. This is because our soils, climate and trees species naturally produce seed or sprouting from stumps to regrow our forests. A key part of a forester’s job is to design harvests in such a way to quickly and naturally regenerate the forest.
Securing Northeast Forest Carbon Program is an effort by the state governments in the seven-state New England and New York region to educate about forest carbon and the role trees and forests play in combatting climate change. A clearinghouse of information on forest carbon is at the Program website at www.northeastforestcarbon.org.
Wood has been used as a building material for millennia. And it has been used for furniture that long, too. When Europeans and others colonized the northeast, wood was, for the most part, their only building material. First, as log homes, and later as timber frame structures, and more recently as “stick-built” structures using two-by-fours and other structural sizes as the frame and other wood materials for sheathing and roof. We still do that today in the northeast, but in commercial buildings, the increased use of concrete and steel as the main building materials has increased dramatically over the last 100 years or so. But these buildings are not climate-friendly. Cement production is one of the leading worldwide sources of greenhouse gas emissions and steel production is very carbon intensive.
Using wood as the main building product is much more climate-friendly and less carbon intensive than steel and concrete. And when solid wood is placed in buildings, this serves as long-term storage of carbon so it is not released into the atmosphere. A comparison of three floor designs for buildings (Edmunds and Lippke 2004) shows that a full wood floor is five times less carbon intensive to make and install compared to steel floor designs and almost three times less carbon intensive than a concrete slab floor (Figure 3). Plus, the wood floor stores carbon for a long period of time.
Figure 3 – Source: Edmunds and Lippke 2004 Please click on the image to enlarge it.
Timber and wood products made from trees are ubiquitous in the northeast, and the forest products infrastructure (foresters, loggers, truckers, sawmills, etc.) is very robust. Increasing wood use for building construction is entirely plausible as part of our climate solution while having our forests serve as carbon sinks as they grow. The increase in lumber prices you may have heard about recently has been due to the pandemic’s effects on the economy and the supply chain for lumber. Lumber prices have already started to drop down to pre-pandemic levels.
A fantastic movement, begun in Western Europe 20 years ago or so is called “mass timber.” Mass timber is a building technique coined to describe the use of solid glulam beams (stacked and glued structural lumber) and cross-laminated timber (CLT) to build tall buildings – now up to 18 stories tall with a new building code being adopted around this country. CLT is structural lumber glued into huge panels (see Woodworks for more info on mass timber at www.woodworks.org).
Figure 4 – Mass timber apartment building
Mass timber buildings replace the customary use of steel and concrete as the main building components and the result is a much more carbon-friendly building – by leaps and bounds – and also provides for the long-term storage of carbon in the wood in the buildings (Figure 4). Lastly, these buildings are simply beautiful – aesthetically warm and pleasing compared to steel and concrete.
This kind of building technique can also be used on smaller buildings or as part of a hybrid where CLT floors are used in a conventionally-built wood building. All of it points to more use of wood in buildings, less use of steel and concrete, with multiple benefits for the planet and for the forests of the northeast.
Leakage
We discussed the leakage issue in our earlier article, but it is so important that we need to quickly cover it again here. Simple thinking says if we don’t cut trees then the planet will be better off because trees sequester carbon. The problem with that thinking is the issue of leakage. Leakage from a forest carbon perspective is that if you don’t harvest a tree here for products, it will be harvested somewhere else because demand for wood products is increasing in our region, the country and the world. It is naïve to think that if we stop harvesting a tree on a property or in our region that there are only positive climate effects. In the northeast U.S., we have laws and regulations to assure that timber harvesting is done in an environmentally sound manner. If we don’t harvest trees here, they will be harvested elsewhere – and maybe in parts of the world with less resilient forests like the rainforests of South America or in places where harvesting is not done in an environmentally-friendly way. This would not be better for the planet.
So, the key point here is that using wood products made from trees in northeastern forests is a very environmentally and carbon-friendly practice. Not harvesting timber here, but continuing to use it for building and energy just pushes the demand for forest products to other forest harvesting elsewhere and does not result in an improvement in our global climate change situation.
Charles Levesque is President of Innovative Natural Resource Solutions, LLC – a northeastern U.S.-based consulting firm. He also serves as Executive Director of the Northeast State Foresters Association and is Coordinator of the new Securing Northeast Forest Carbon Program. He can be reached at levesque@inrsllc.com or 603-588-3272.
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