![]() ![]() When milling logs into lumber, much of the wood becomes small chips or sawdust, some of which are also burned. Bark comprises 10-15% of the wood removed from the forest and is generally burned. ![]() When a tree is harvested, a third or more of its wood is typically left behind in the forest as roots or small branches that then decompose. Unfortunately, only a small portion of a harvested tree typically makes it into a building. If a whole tree, roots and all, were somehow transferred into a building, this carbon would likely remain stored for decades, so none of the tree’s carbon would be emitted and warm the climate. When trees grow, they transform carbon in the air into wood, removing it from the atmosphere and storing it. Here are five interrelated reasons that turning to more wood for buildings is not a climate- or environmentally friendly solution overall: 1) Most wood (and its stored carbon) is lost during production. And currently, the fast-growing plantations that could supply wood in these conditions are already needed to meet other growing demands for wood. In our report, The Global Land Squeeze: Managing Growing Competition for Land, we do find that using wood to replace concrete and steel could have lower emissions under certain conditions, but they’re challenging to achieve. Truly “mass” timber would also require vast additional harvesting of the world’s forests. But new research finds that using wood in construction is likely to increase emissions for many decades, even relative to using concrete and steel. New ways of gluing pieces of wood together to form strong beams and structural panels provide opportunities to use wood even in tall buildings. ![]() Because concrete and steel used to construct buildings are a major source of global greenhouse gas emissions, there is growing interest in “mass timber” - a supposedly lower-carbon option - to replace them. ![]()
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