The United Nations Framework Convention on Climate Change defines carbon sequestration as "the process of removing carbon from the atmosphere and depositing it in a reservoir."
In the past few years, the carbon sequestration has become the main focus of discussion for the perceived environmental benefits of wood products as both forests and wood products can be used as reservoirs to store carbon. Although the CSSBI actively represents the sheet steel buiding product industry, we would like to stress that we also openly advocate for the principal of using the best suited construction material for each individual application or project, and not simply favouring one material over another without considering all aspects of the material. Many construction products, including steel, concrete and wood have various environmental benefits and tradeoffs that should be thoroughly considered before material selection decisions are made.
There are several reports that recommend and support the principal of carbon sequestration as it relates to wood products, but as is the case for everything, there is always two sides to any argument. We have compiled below a number of resources, articles and reports which we hope will further educate on the subject of carbon sequestration and demonstrate that this is a very complicated and multi-faceted issue.
The following journal article written by Ann Ingerson was published by Springer Science + Business Media B.V. and was published online October 23, 2010.
Carbon storage potential of harvested wood: summary and policy implications
Within national greenhouse gas inventories, many countries now use widelyaccepted methodologies to track carbon that continues to be stored in wood products and landfills after its removal from the forest. Beyond simply tracking post-harvest wood carbon, expansion of this pool has further been suggested as a potential climate change mitigation strategy. This paper summarizes data on the fate of carbon through the wood processing chain and on greenhouse gas emissions generated by processing, transport, use and disposal of wood. As a result of wood waste and decomposition, the carbon stored long-term in harvested wood products may be a small proportion of that originally stored in the standing trees—across the United States approximately 1% may remain in products inuse and 13% in landfills at 100 years post-harvest. Related processing and transport emissions may in some cases approach the amount of CO2e stored in long-lived solid wood products. Policies that promote wood product carbon storage as a climate mitigation strategy must assess full life-cycle impacts, address accounting uncertainties, and balance multiple public values derived from forests.
Carbon Sequestration and Storage and Wood Waste
It is true that trees sequester carbon as they grow and that entire forests can sequester large amounts of carbon dioxide as they mature. It is also true that when trees are harvested and manufacturered into various wood products for construction that they continue to store carbon, however we need to look at the whole lifecycle of building materials and consider what happens at the end of their useful life.
Wood waste from manufacturing, construction and demolition activities decomposes in landfills to create methane - a greenhouse gas that contributes to climate change at a much greater rate than carbon dioxide. In 2005, Canadian wood waste in landfills accounted for 24.4 mT of greenhouse gases - the equivalent of 4.7 million passenger vehicles on our roads. This data and more information is available in the following publication released by the Forest Products Association of Canada.
Wood Waste for Generating Energy
Biomass from forests and waste from the manufacture of wood products can be used for energy production. This type of energy production is gaining in popularity in Canada and although on the surface it may seem like a logical solution to ending our dependence on fossil fuels, Greenpeace Canada has compiled a report that clearly states that biomass energy generation is not an environmentally sustainable method of energy production.
As referenced on page 18 of the report "Burning wood emits a lot of carbon dioxide – typically every tonne of wood (45% moisture content) emits 1 tonne of CO2 when burned(115). In the US, some biomass facilities have been shown to emit up to 150% more CO2 than they would if they were burning coal and up to 400% times more CO2 than if they were burning natural gas for the same amount of electricity produced*(115-117)."