Wood burning is defined as carbon neutral because trees assimilate the same amount of CO2 throughout their lifetime as the amount released when wood is burned. But on closer inspection, it becomes clear that wood burning isn’t climate-neutral at all:
- Soot /black carbon: Wood burning produces short-lived climate-forcing pollutants. The most relevant one is soot or black carbon. Although biomass burning only seems to have a slightly total warming effect in the long run, the negative impact on the climate is masked in many ways: Firstly, soot directly affects the immediate environment by absorbing sunlight. Secondly, there are substantial indirect effects due to its impact on cloud formation and precipitation as well as deposition on ice surfaces. As soot particles are transported over large distances, they also harm sensitive eco-systems – such as the arctic – that are far away from the initial sources of pollution.
- Inefficient: Often, wood burning is used to create a cozy ambience or as a supplementary source of heating. This applies for many local space heaters, especially if heat output is over-designed compared with their location. The heat output of such appliances often can only be adjusted poorly and excess heat is not absorbed by a buffer.
- Wrong incentives: Since wood is cheap fuel, home owners may consider energy renovation and better insulation as not profitable.
- Deforestation: If the level of reforestation isn’t adequate and burning of wood take place faster than the new trees grow, wood burning does lead to increasing net CO2 levels in the atmosphere. In addition, forests and forest floors serve as a crucial carbon sink – with regard to the global climate targets forests stand must not be reduced.
- Origin: If wood is imported or transported over large distances, CO2 emissions from transport have to be considered as well. The same holds true for the energy-related carbon footprint, if wood is technically dried.