|Characterisation Method Name:|
|CO2 impact on Wood|
|Principal Method Name:|
|EPS: elevated temperature pathway and fertilisation pathway|
|Model 1, elevated temperature pathway|
The characterisation factor is determined by a mechanistic method.
No attempt to quantitatively forecast altered forest growth as a consequence of global warming has been found. In a very long time perspective the forest belts may move towards the poles in a similar way as the agricultural areas are expected to do. In the 100-year perspective often used for the greenhouse effects, there is only time for one generation of trees in the boreal region and if no diseases or insects or competitors attack the trees a net increase in production seems likely. However in the more arid areas and in the tropical areas, water is more important for the growth rate than temperature and the consequence of global warming is more difficult to forecast.
For the boreal region a model describing nitrogen mineralisation rates in soil at different temperatures (Jansson, 1999) may be used to estimate the growth increase. According to this an increased temperature of 1.5 o C would give an increased nitrogen mineralisation of 12% in the boreal and mixed temperate forests. Assuming that nitrogen availability is growth limiting to 50% (the rest mainly due to water deficiency) the growth increase would be 6%. The world production of round timber from this region is about 3.5 billion m 3 /year corresponding to roughly 1.5 billion ton DS(Dry Substance) wood. 6% of this is 92 million tons/yr or 9.2×10 12 kg per 100 year.
The characterisation factor for this pathway is
-9.2E+12 *1.26E–16 = -1.16E–03 kg DS wood/kg CO2
Model 2, CO2 fertilisation pathway
The characterisation factor is determined by an empirical method.
Category indicator value in system considered IPCC (Intergovernmental Panel on Climate Change) (1994) estimates that the increased uptake of CO2 from the atmosphere from vegetation was between 0.5 to 2.0 Gton C/yr during the 1980ies. During the 80ies the CO2 concentration was about 75 ppmv above pre-industrial levels. As an average the increased CO2-levels for the next 100 years are estimated to about 220 ppmv for the IS92a scenario. However IPCC assumes that no direct linearity exists between the
increased CO2 concentration and the increased vegetation growth rate, as other factors like access to water and nutrients also influence the growth rate. It is reasonable to assume that the CO2 fertilisation effect is less effective per molecule as the concentration increases. It is therefore assumed that the net increase of CO2 uptake will be doubled as an average for the next 100 years, i.e. 2.5 Gton C/yr.
Roughly half of this is estimated to be bound in timber, thus resulting in a growth increase of 0.5*2.5*30/12 = 3.12 Gton wood (dry substance)/yr = 3.12·10 12 kg wood/yr.
30 is the mole weight of CH2O the average molecular element of wood and 12 is the mole weight of carbon.
The characterisation factor for this pathway
For the time period of 100 years we get -3.12·10 12 kg wood/yr*100yr*1.26×10 –16 kg -1 = -0.0393 kg wood/kg CO2.
For both pathways the added characterisation factor is - 0.00116 + (- 0.0393) = - 0.0405 kg wood(DS)/kg CO2.
|1. IPPC, “The 1994 Report of the Scientific Assessment Working Group of IPCC. Summary for policymakers”, WMO and UNEP, 1994 2. Jansson, P-E.,Persson, T. och Kätterer, T., (1999).”Nitrogen Processes in Arable and Forest Soils in the Nordic Countries”, Tema Nord, Report 1999:560 from Nordic Council of Ministers, Copenhagen, 1999.|
|The impact is of global character. The modelled system is therefore global. The temporal system borders are 100 years (1990-2090). The society affected is the one described in IPCC scenario IS92A. (IPCC, 1990).|
|Characterisation Parameter||Category Indicator||Impact Indication Principle||Aspect||Substance||Quantity||Unit||Notes|