An Analysis of GWPbio and the Effects of Scale (WP-20-07)
A variety of methods and metrics have been proposed to quantify the impacts of biogenic CO2 emissions. Most consider biogenic CO2 in the context of the biogenic carbon cycle, recognizing that this cycle requires that biogenic CO2 be differentiated from fossil CO2. One of the metrics receiving attention is GWPbio (Cherubini et al. 2011).
The GWPbio metric provides a plot-level means for incorporating the biogenic carbon cycle into estimates of the global warming impact of biogenic CO2 emissions.
This white paper examines the assertion that plot- and landscape-scale approaches are equivalent (and hence that use of GWPbio can be reconciled with a landscape approach). The authors test the use of GWPbio under several scenarios and discuss challenges in its application. The white paper concludes that, although the metric provides useful information and can be easily calculated for simple scenarios, it contains several embedded assumptions and conventions that (a) have large impacts on results and (b) may be inappropriate in several contexts.