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Balancing human communities’ and ecosystems’ need for freshwater is one of the major challenges of the 21st century as population growth and improved living conditions put increasing pressure on freshwater resources. While frameworks to assess the environmental impacts of freshwater consumption have been proposed at the regional scale, an operational method to evaluate the consequences of consumption on different compartments of the water system and account for their interdependence is missing at the global scale. Here, we develop depletion factors that simultaneously quantify the effects of water consumption on streamflow, groundwater storage, soil moisture, and evapotranspiration globally. We estimate freshwater availability and water consumption using the output of a global-scale surface water-groundwater model for the period 1960-2000. The resulting depletion factors are provided for 8,664 river basins, representing 93% of the landmass with significant water consumption, i.e., excluding Greenland, Antarctica, deserts, and permanently frozen areas. Our findings show that water consumption leads to the largest water loss in rivers, followed by aquifers and soil, while simultaneously increasing evapotranspiration. Depletion factors vary regionally with ranges of up to four orders of magnitude depending on the annual consumption level, the type of water used, aridity, and water transfers between compartments. Our depletion factors provide valuable insights into the intertwined effects of surface and groundwater consumption on several hydrological variables over a specified period. The developed depletion factors can be integrated into sustainability assessment tools to quantify the ecological impacts of water consumption and help guide sustainable water management strategies, while accounting for the performance limitations of the underlying model.

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 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 on regional riverine fish species richness and irreversible global losses, including up-to-date species data, and providing spatially explicit values with high geographical coverage. info:eu-repo/semantics/publishedVersion

Aircraft engine manufacturers have been reported to cause great environmental impacts within the aircraft manufacturing industry, with a large contribution stemming from the integrated bladed rotors due to special manufacturing requirements. Here we assess all relevant life cycle environmental impacts of manufacturing a Ti-6Al-4 V alloy rotor and investigate potential impact reductions resulting from different recycling scenarios for alloy chips. The hot spot analysis shows a dominance of the material stage compared to manufacturing and hazardous waste disposal. 100% recycling of titanium chips into alloy gives a 52% reduced climate change impact compared to the conventional hazardous waste treatment of the chips.

The aeronautics sector has been regarded as an important contributor to environmental problems, due to aircraft fuel consumption and combustion emissions. Little is known about the other parts of the value chain, in particular the aircraft manufacturing. The complexity of aircraft systems and the lack of public data have prevented analysis of disaggregated contributions of the value chain to key environmental problems - analysis that could provide valuable insight to reduce environmental impacts. We have addressed this knowledge gap by developing a new mapping method to quantify the environmental burden of the aeronautics manufacturing sector. The mapping builds on environmental databases and available market data representing 84% of the sector’s sales in 2017. Our mapping results show that material production and aircraft manufacturing consumed 69.5 TWh energy, emitted 18.1 MtCO2e, and withdrew 475 million m3 water, with the largest contributions stemming from airframe manufacturers and aluminium alloy production. Carbon emissions predominantly occur in the manufacturing stage while water withdrawals mainly originate from the material production. These findings demonstrate the relevance of adopting a life cycle perspective, covering the entire value chain, and the importance of ensuring a broad coverage of environmental problems to obtain a comprehensive view of the sector’s environmental impacts. Based on our findings, we provide decision-makers in the aeronautics sector with specific recommendations to prioritize their actions and steer towards a more environmentally sustainable industry.