Estimating water consumption of potential natural vegetation on global dry lands: building an LCA framework for green water flows

Green water appropriation of the cropland ecosystem in China

Despite the awareness that green water is the main source of water to produce food, studies on green water use in cropland ecosystems are still rather limited, and almost no research has so far explored the relationship between green water utilization and socioeconomic development. In this study, with the help of CropWat 8.0, the green water footprint (GWF) of main crops in China was estimated from 1979 to 2016. On this basis, a novel concept, i.e., green water appropriation rate (GWar), was introduced to reveal the relationship between GWF and precipitation. Then, for the first time, the center of gravity trajectory of the GWar and the correlation between GWar and socioeconomic factors were further investigated. The results show that the provinces with the largest increases of GWF were Inner Mongolia (223%), Xinjiang (127%), and Ningxia (123%), while the GWF of 11 provinces has decreased, and 9 of them were municipalities or coastal areas. Generally, the GWar in the eastern and central provinces was higher than that in the western provinces. The center of gravity of the GWar has always been in Henan Province, but it has moved westward from Kaifeng City in 1979 to Sanmenxia City in 2016 and may further move to Shanxi Province soon. The total power of agricultural machinery and the effective irrigation rate had a positive correlation with the GWar, while the agricultural GDP was negatively correlated with the GWar. It is expected that the results will explicitly provide a scientific basis for the development of water-appropriate agriculture and the full utilization of rainwater.

Effects of different Danish food consumption patterns on Water ScarcityFootprint

Food production and consumption have been recognized as a major source of environmental impacts. To ensure food security and a sustainable food system, dietary changes have been identified as one of the valuable strategies to reduce impacts on the environment while promoting human health. The vast majority of scientific literature has been focused on the effects of food consumption on climate change while neglecting to assess the degree of water scarcity impacts due to water consumption embodied in food. The research paper investigates the nexus between food consumption and impacts on water consumption adding important findings to a more recent growing body of studies estimating the water footprint (WF) of different dietary scenarios. This study uses the Water Footprint Network methodology and the AWARE (Available Water REmaining) characterization model to assess both the WF and the blue WSF (water scarcity footprint), respectively, of four Danish diets: standard, carnivore, vegetarian and vegan. In order to make them comparable, a total intake of 2000 kcal person^-1 day^-1 was set as energetic reference for all the diet scenarios considered. Using detailed trade and production data of agri-foods, we were able to assess the location of primary production and consequently to reveal countries mainly affected by water scarcity associated with import to satisfy Danish diets consumption. We found that while the vegan scenario scored the best environmental profile requiring 1489 L/cap/day calculated with the volumetric WF approach, it has the largest potential impacts on blue WSF of 10,477 L_H20-eq/cap/day. This study has shown that more than 90% of impacts on water consumption occur outside the national borders, as a consequence of large quantities of fruits and nuts imported by countries already threatened by high water scarcity conditions such as USA and Mediterranean regions. This methodological approach may be used to compare environmental performances of recommended dietary guidelines and to assess impact scenarios of new trade policies, protecting local water scarcity levels.

Considering the Fate of Evaporated Water Across Basin Boundaries-Implications for Water Footprinting

Water consumption along value chains of goods and services has increased globally and led to increased attention on water footprinting. Most global water consumption is accounted for by evaporation (E), which is connected via bridges of atmospheric moisture transport to other regions on Earth. However, the resultant source-receptor relationships between different drainage basins have not yet been considered in water footprinting. Based on a previously developed data set on the fate of land evaporation, we aim to close this gap by using comprehensive information on evaporation recycling in water footprinting for the first time. By considering both basin internal evaporation recycling (BIER; >5% in 2% of the world's basins) and basin external evaporation recycling (BEER; >50% in 37% of the world's basins), we were able to use three types of water inventories (basin internal, basin external, and transboundary inventories), which imply different evaluation perspectives in water footprinting. Drawing on recently developed impact assessment methods, we produced characterization models for assessing the impacts of blue and green water evaporation on blue water availability for all evaluation perspectives. The results show that the negative effects of evaporation in the originating basins are counteracted (and partly overcompensated) by the positive effects of reprecipitation in receiving basins. By aggregating them, combined net impacts can be determined. While we argue that these offset results should not be used as a standalone evaluation, the water footprint community should consider atmospheric moisture recycling in future standards and guidelines.

Water Footprint and Life Cycle Assessment: The Complementary Strengths of Analyzing Global Freshwater Appropriation and Resulting Local Impacts

Considering that 4 billion people are living in water-stressed regions and that global water consumption is predicted to increase continuously [...]

Water footprint of German agricultural imports: Local impacts due to global trade flows in a fifteen-year perspective

This study investigates the water scarcity footprint (WSF) trend of German agricultural imports over recent years, following the principles of the ISO 14046 standard on water footprinting. For this purpose, the import statistics of agricultural goods for the years 2000, 2005, 2010, and 2015 was compiled and linked with the irrigation water consumption during their production as well as with the AWARE water scarcity factors of the country of production. Agricultural imports increased by 62% from 22 to 35 million tons during the analysed period. At the same time, the blue water consumption for agricultural production (i.e., irrigation water) decreased by 13% and the WSF declined by 20%, from 119 to 91 km³_{world-equivalents (world-eq.)}. The decrease in WSF is caused by drop in the cotton imports, while the WSF associated with the imports of other crops increased by 45%. Product-wise, cotton, nuts, and rice contribute to more than half of the total WSF in all analysed years. Despite their high WSF, these products account for only 3% of the imports by mass confirming the relevance of impact based water footprint assessments. Country-wise, main contributors change along the analysed years. In the year 2000, one-quarter of the WSF occurs in Uzbekistan due to cotton imports. Afterwards, the highest WSF arises in Iran and Spain, while the imports from the US dominate the WSF in 2015. The changing trend follows the pattern of production of the hotspots identified on the product level, e.g. nuts, soybeans, and cotton. This study provides information on the water scarcity impacts that the German consumption creates in other countries and may be useful for decision-making processes aiming at optimising water scarcity footprints.

Water scarcity footprint of dairy milk production in New Zealand - A comparison of methods and spatio-temporal resolution

Water scarcity footprinting now has a consensual life cycle impact assessment indicator recommended by the UNEP/SETAC Life Cycle Initiative called AWaRe. It was used in this study to calculate the water scarcity footprint of New Zealand (NZ) milk produced in two contrasting regions; "non-irrigated moderate rainfall" (Waikato) and "irrigated low rainfall" (Canterbury). Two different spatial and temporal resolutions for the inventory flows and characterisation factors (CFs) were tested and compared: country and annual vs. regional and monthly resolution. An inventory of all the consumed water flows was carried out from cradle to farm-gate, i.e. from the production of dairy farm inputs to the milk and meat leaving the dairy farm, including all water uses on-farm such as irrigation water, cow drinking water and cleaning water. The results clearly showed the potential overestimation of a water scarcity footprint when using aggregated CFs. Impacts decreased by 74% (Waikato) and 33% (Canterbury) when regional and monthly CFs were used instead of country and annual CFs. The water scarcity footprint calculated at the regional and monthly resolution was 22 L_{world eq}/kg FPCM (Fat Protein Corrected Milk) for Waikato milk, and 1118 L_{world eq}/kg FPCM for Canterbury milk. The contribution of background processes dominated for milk from non-irrigated pasture, but was negligible for milk from irrigated pasture, where irrigation dominated the impacts. Results were also compared with the previously widely-used Pfister method (Pfister et al., 2009) and showed very similar ranking in terms of contribution analysis. An endpoint indicator was evaluated and showed damages to human health of 7.66 × 10^-5 DALY/kg FPCM for Waikato and 2.05 × 10^-3 DALY/kg FPCM for Canterbury, but the relevance of this indicator for food production needs reviewing. To conclude, this study highlighted the importance of using high-resolution CFs rather than aggregated CFs.

A characterisation model to address the environmental impact of green water flows for water scarcity footprints

The development of methods to assess the potential environmental impact of green water consumption in life cycle assessment has lagged behind those for blue water use, which are now routinely applied in industrial and policy-related studies. This represents a critical gap in the assessment of land-based production systems and the ability to inform policy related to the bio-economy. Combining satellite remote sensing and meteorological data sets, this study develops two new sets of spatially-differentiated and globally applicable characterisation factors (CFs) to assess the environmental impact of green water flows in LCA. One set of CFs addresses the impact of shifts in water vapour flow by evapotranspiration on blue water availability (CFWS) and the other set of CFs addresses moisture recycling within a basin (CFWA). Furthermore, as an additional and optional step, these two indicators are combined into an aggregated green water scarcity indicator, representing the global variability of green water scarcity. The values obtained for CFWA show that there are significant changes in green water flows that were returned to the atmosphere in Alaska (covered by open shrublands) and in some central regions of China (covered by grasslands and barren or sparsely vegetated land), where precipitation levels are lower than 10 mm/yr. The results obtained for CFWS indicate that severe perturbations in surface blue water production occur, particularly in central regions of China (covered by grasslands), the southeast of Australia (covered by evergreen broadleaf forest) and in some central regions of the USA (covered by grassland and evergreen needleleaf forest). The application of the green water scarcity CFs enables the evaluation of the potential environmental impact due to green water consumption by agricultural and forestry products, informing both technical and non-technical audiences and decision-makers for the purpose of strategic planning of land use and to identify green water protection measures.

BOARD-INVITED REVIEW: Quantifying water use in ruminant production

The depletion of water resources, in terms of both quantity and quality, has become a major concern both locally and globally. Ruminants, in particular, are under increased public scrutiny due to their relatively high water use per unit of meat or milk produced. Estimating the water footprint of livestock production is a relatively new field of research for which methods are still evolving. This review describes the approaches used to quantify water use in ruminant production systems as well as the methodological and conceptual issues associated with each approach. Water use estimates for the main products from ruminant production systems are also presented, along with possible management strategies to reduce water use. In the past, quantifying water withdrawal in ruminant production focused on the water demand for drinking or operational purposes. Recently, the recognition of water as a scarce resource has led to the development of several methodologies including water footprint assessment, life cycle assessment, and livestock water productivity to assess water use and its environmental impacts. These methods differ with respect to their target outcome (efficiency or environmental impacts), geographic focus (local or global), description of water sources (green, blue, and gray), handling of water quality concerns, the interpretation of environmental impacts, and the metric by which results are communicated (volumetric units or impact equivalents). Ruminant production is a complex activity where animals are often reared at different sites using a range of resources over their lifetime. Additional water use occurs during slaughter, product processing, and packaging. Estimating water use at the various stages of meat and milk production and communicating those estimates will help producers and other stakeholders identify hotspots and implement strategies to improve water use efficiency. Improvements in ruminant productivity (i.e., BW and milk production) and reproductive efficiency can also reduce the water footprint per unit product. However, given that feed production makes up the majority of water use by ruminants, research and development efforts should focus on this area. More research and clarity are needed to examine the validity of assumptions and possible trade-offs between ruminants' water use and other sustainability indicators.

Understanding the LCA and ISO water footprint: A response to Hoekstra (2016) "A critique on the water-scarcity weighted water footprint in LCA"

Water footprinting has emerged as an important approach to assess water use related effects from consumption of goods and services. Assessment methods are proposed by two different communities, the Water Footprint Network (WFN) and the Life Cycle Assessment (LCA) community. The proposed methods are broadly similar and encompass both the computation of water use and its impacts, but differ in communication of a water footprint result. In this paper, we explain the role and goal of LCA and ISO-compatible water footprinting and resolve the six issues raised by Hoekstra (2016) in "A critique on the water-scarcity weighted water footprint in LCA". By clarifying the concerns, we identify both the overlapping goals in the WFN and LCA water footprint assessments and discrepancies between them. The main differing perspective between the WFN and LCA-based approach seems to relate to the fact that LCA aims to account for environmental impacts, while the WFN aims to account for water productivity of global fresh water as a limited resource. We conclude that there is potential to use synergies in research for the two approaches and highlight the need for proper declaration of the methods applied.

Land Use in LCA: Including Regionally Altered Precipitation to Quantify Ecosystem Damage

The incorporation of soil moisture regenerated by precipitation, or green water, into life cycle assessment has been of growing interest given the global importance of this resource for terrestrial ecosystems and food production. This paper proposes a new impact assessment model to relate land and water use in seasonally dry, semiarid, and arid regions where precipitation and evapotranspiration are closely coupled. We introduce the Precipitation Reduction Potential midpoint impact representing the change in downwind precipitation as a result of a land transformation and occupation activity. Then, our end-point impact model quantifies terrestrial ecosystem damage as a function of precipitation loss using a relationship between woody plant species richness, water and energy regimes. We then apply the midpoint and end-point models to the production of soybean in Southeastern Amazonia which has resulted from the expansion of cropland into tropical forest, with noted effects on local precipitation. Our proposed cause-effect chain represents a complementary approach to previous contributions which have focused on water consumption impacts and/or have represented evapotranspiration as a loss to the water cycle.

Life cycle assessment of forecasting scenarios for urban water management: A first implementation of the WaLA model on Paris suburban area

A framework and an associated modeling tool to perform life cycle assessment (LCA) of urban water system, namely the WaLA model, has been recently developed. In this paper, the WaLA model is applied to a real case study: the urban water system of the Paris suburban area, in France. It aims to verify the capacity of the model to provide environmental insights to stakeholder's issues related to future trends influencing the system (e.g., evolution of water demand, increasing water scarcity) or policy responses (e.g., choices of water resources and technologies). This is achieved by evaluating a baseline scenario for 2012 and several forecasting scenarios for 2022 and 2050. The scenarios are designed through the modeling tool WaLA, which is implemented in Simulink/Matlab: it combines components representing the different technologies, users and resources of the UWS. The life cycle inventories of the technologies and users components include water quantity and quality changes, specific operation (electricity, chemicals) and infrastructures data (construction materials). The methods selected for the LCIA are midpoint ILCD, midpoint water deprivation impacts at the sub-river basin scale, and endpoint Impact 2002+. The results of the baseline scenario show that wastewater treatment plants have the highest impacts compared to drinking water production and distribution, as traditionally encountered in LCA of UWS. The results of the forecasting scenarios show important changes in water deprivation impacts due to water management choices or effects of climate change. They also enable to identify tradeoffs with other impact categories and to compare several scenarios. It suggests the capacity of the model to deliver information for decision making about future policies.

Assessing biodiversity loss due to land use with Life Cycle Assessment: are we there yet?

Ecosystems are under increasing pressure from human activities, with land use and land-use change at the forefront of the drivers that provoke global and regional biodiversity loss. The first step in addressing the challenge of how to reverse the negative outlook for the coming years starts with measuring environmental loss rates and assigning responsibilities. Pinpointing the global pressures on biodiversity is a task best addressed using holistic models such as Life Cycle Assessment (LCA). LCA is the leading method for calculating cradle-to-grave environmental impacts of products and services; it is actively promoted by many public policies, and integrated as part of environmental information systems within private companies. LCA already deals with the potential biodiversity impacts of land use, but there are significant obstacles to overcome before its models grasp the full reach of the phenomena involved. In this review, we discuss some pressing issues that need to be addressed. LCA mainly introduces biodiversity as an endpoint category modeled as a loss in species richness due to the conversion and use of land over time and space. The functional and population effects on biodiversity are mostly absent due to the emphasis on species accumulation with limited geographic and taxonomical reach. Current land-use modeling activities that use biodiversity indicators tend to oversimplify the real dynamics and complexity of the interactions of species among each other and with their habitats. To identify the main areas for improvement, we systematically reviewed LCA studies on land use that had findings related to global change and conservation ecology. We provide suggestion as to how to address some of the issues raised. Our overall objective was to encourage companies to monitor and take concrete steps to address the impacts of land use on biodiversity on a broader geographical scale and along increasingly globalized supply chains.