Reduced river discharge and flow regulation are significant threats to freshwater biodiversity. An accurate representation of potential damage of water consumption on freshwater biodiversity is... Show moreReduced river discharge and flow regulation are significant threats to freshwater biodiversity. An accurate representation of potential damage of water consumption on freshwater biodiversity is required to quantify and compare the environmental impacts of global value chains. The effect of discharge reduction on fish species richness was previously modeled in life cycle impact assessment, but models were limited by the restricted geographical scope of underlying species-discharge relationships and the small number of species data. Here, we propose a model based on a novel regionalized species-discharge relationship (SDR). Our SDR-based model covers 88 % of the global landmass (2320 river basins worldwide excluding deserts and permanently frozen areas) and is based on a global dataset of 11,450 riverine fish species, simulated river discharge, elevation, and climate zones. We performed 10-fold cross-validation to select the best set of predictors and validated the obtained SDRs based on observed discharge data. Our model performed better than previous SDRs employed in life cycle impact assessment (Kling-Gupta efficiency coefficient about 4 times larger). We provide both marginal and average models with their uncertainty ranges for assessing scenarios of small and large-scale water consumption, respectively, and include regional and global species loss. We conducted an illustrative case study to showcase the method's applicability and highlight the differences with the currently used approach. Our models are useful for supporting sustainable water consumption and riverine fish biodiversity conservation decisions. They enable a more specific, reliable, and complete impact assessment by differentiating impacts Show less
Li, D.; Dorber, M.; Barbarossa, V.; Verones, F. 2022
Water temperature is an abiotic master variable for the survival of aquatic organisms. Global warming alters the thermal regimes of rivers and, thus, poses a threat to freshwater biodiversity. To... Show moreWater temperature is an abiotic master variable for the survival of aquatic organisms. Global warming alters the thermal regimes of rivers and, thus, poses a threat to freshwater biodiversity. To address the impacts of water temperature changes related to global warming on freshwater fish species in life cycle assessment (LCA), we developed spatially explicit characterization factors (CFs) for 207 greenhouse gases under four representative concentration pathways. We calculated fate factors by using the output of a global hydrological model fully coupled with a dynamic water temperature model. We developed six species sensitivity distribution curves for two thermal effects (i.e., lethal and sub-lethal) to derive effect factors, which take the differences in sensitivity between climate regions into account. The regional CFs for CO2 ranged from 2.91 x 10(-22) to 6.53 x 10(-18) PAF.yr/kg for sub-lethal effects and from 1.98 x 10(-22) to 4.58 x 10(-18) PDF.yr/kg for lethal effects, depending on the river watersheds and future climate scenarios. To identify the contribution of regional impacts on freshwater fish to their potential global extinction, the regional CFs were converted into global CFs. The largest CFs always occur in the tropical watersheds. The regional impacts in the Amazon watershed contribute the most to the global freshwater fish species extinction. This study contributes to assessing the potential impacts on freshwater biodiversity from global warming from a new cause-effect pathway in LCA. Show less
Verones, F.; Kuipers, K.; Núnez, M.; Rosa, F.; Scherer, L.; Marques, A.; ... ; Dorber, M. 2022
Human activities put pressure on the natural environmental and the Life Cycle Assessment methodology (LCA) is becoming a more prevalent tool to assess the relevant environmental impacts from... Show moreHuman activities put pressure on the natural environmental and the Life Cycle Assessment methodology (LCA) is becoming a more prevalent tool to assess the relevant environmental impacts from products and processes on terrestrial, marine and freshwater ecosystems. The Global Life Cycle Impact Assessment Method (GLAM) project of the Life Cycle Initiative hosted by the UN Environment Programme aims at making recommendations for new impact assessment models (such as for land use, water consumption and eutrophication) and improving the consistency and comparability across impact categories. An important aspect to ensure the comparability of these categories across geographic regions is to identify and quantify the scale of impacts, i.e., distinguish if an impact to an area results in local species losses or global species extinctions. This distinction is of high relevance because a species lost at a local level may still exist in other regions of the world and could potentially reestablish in that area, whereas global extinctions are irreversible. A consistent approach to scale impacts from local to global scales is currently not implemented within the LCIA framework, but is crucial to appropriately consider potential biodiversity impacts across impact categories. Here we present an updated approach for calculating a scaling factor, called the Global Extinction Probability (GEP), and calculate it for more than 98 000 species in 20 species groups across marine, terrestrial and freshwater ecosystems. We also provide the GEPs for different spatial scales, such as grid cells, ecoregions or watersheds and country averages. We found that GEP varies over orders of magnitude across the world, emphasizing the relevance of considering the spatial dimension of such extinction probabilities. We recommend quantifying global extinctions based on local species loss by multiplying local species loss within a certain spatial unit with the GEP corresponding to the same spatial unit. GEPs harmonize the quantification of biodiversity impacts across impact categories, improving information to support environmental decision-making. Show less
