The use of wood products positively influences the release of emissions, as they substitute products that cause more CO2 emissions on their manufacturing. They also can be used for energy generation at their end of life, thus replacing fossil fuels. Numerous results of LCA studies reveal the climatic advantages of products and building components containing a high share of wood compared with products on a material basis other than biomass; this especially applies when they are used for energy at the end of their life cycle. However, it is very difficult to quantify the effect of material substitution on national level. This is due to the fact, that products or systems, such as building components, can only be compared in individual cases, taking into account the same functional characteristics.
The substitution effects of wood utilization are assessed in the project Oekopot.
Carbon storage effect
Wood products also act as carbon pools, as they prolong the storage of carbon by their respective service lifetime. It is the carbon that was removed by the trees during their growth phase in form of CO2 from the atmosphere. Article 1 of the United Nations Framework Convention on Climate Change (UNFCCC), which was adopted in 1992, defines a reservoir or pool as 'a component or components of the climate system where a greenhouse gas is stored'. Wood products are no carbon sink, but constitute such a carbon reservoir or pool, in which the carbon from photosynthesis is transmitted. This means that the storage effect extends the natural carbon cycle.
However, not alone the existence of these pools is relevant to the climate, but their stabilization and increase. Besides the postponing of carbon release, particularly an increasing material use and thereby strengthening of the cascasding wood use benefits the climate.
Deforestation
The basic prerequisite for a positive impact of the global use of wood, however, is a sustainable forest management in terms of conservation of forest carbon stocks. This is even more urgent as about 20 percent of the global CO2-emissions originate from land use changes, of which most of it comes along with deforestation. Especially natural forests are subject to upward pressure worldwide, which not only affects the climate. In addition to the increasing demand for agricultural land for food production and the production of biofuels (palm oil trees, soya, etc.), also the demand for wood plays a major role. The origin of products is therefore of crucial importance. They can only be called climate-friendly, if they originate from sustainably managed forests. Aspects of biodiversity need also to be considered.
Data of the second forest inventory from the year 2002 has shown that the forest cover increased by about 11.1 M hectare in Germany. This constitutes about one third of the country's area. Also the forest stocks increased despite its rising utilization through settlements, industries and the transport sector. This means that especially wood products from sustainably managed domestic forests can have a climate positive impact; due to the substitution and the storage effect.
