Harnessing model ensembles to assess uncertainty and provide prospective characterization factors for AWARE2.0
摘要
Prospective LCAs sometimes neglect how potential future impacts could be affected by future shifts in environmental conditions. Despite expected future changes in water availability, prospective characterization factors (CFs) for the updated freshwater deprivation impact assessment method AWARE, AWARE2.0, do not exist yet. Additionally, interpreting AWARE requires an understanding of its uncertainty. This paper improves the understanding of AWARE2.0’s uncertainty by combining sets of alternative input values for the calculation of regular and of prospective AWARE2.0 CFs.
MethodsData from the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) framework is used to estimate AWARE2.0’s uncertainty and to calculate prospective AWARE2.0 CFs. For the uncertainty assessment, stochastic AWARE2.0 is generated by Monte Carlo sampling from parametric distributions representing AWARE2.0’s input data. Two prospective versions of AWARE2.0 are calculated: A “climate-prospective” model ensemble consisting of five climate models produces prospective CFs under climate change for three scenarios. “Fully prospective” AWARE2.0 additionally integrates projected water demand changes for three shared socioeconomic pathways in a simplified manner.
Results and discussionStochastic AWARE2.0 allows a discussion of major challenges in modeling the uncertainty of AWARE2.0 and suggests that its water availability input can deviate from observations by more than 20%. “Climate prospective AWARE2.0” shows that for many areas the future change in CFs under climate change is primarily determined by the selected climate models instead of the climate scenarios. The ensemble average CFs in some cases still change by more than 50% up to 2049. With the future socioeconomic changes integrated in “fully prospective AWARE2.0”, CF increases are more frequent than when considering climate change only.
ConclusionsThe input model choice for calculating AWARE CFs can considerably affect both regular and prospective CFs. With its prospective CF timeseries, this paper contributes to dynamic and prospective water deprivation LCIA while improving the understanding of input-data related uncertainty in AWARE2.0.