From Water-Use to Water-Scarcity Footprinting in Environmentally Extended Input-Output Analysis

Virtual Water Embodied in Interregional Energy Trade in China: A City-Level Analysis

Large volumes of water are used in energy production for both primary (e.g., fuel extraction) and secondary energy (e.g., electricity). In countries such as China, with a large internal trade in fuels and long-distance transmission grids, this can result in considerable water inequalities. Previous research focused on the water impacts of energy production at the national and provincial levels, which is too coarse to identify the spatial differences and make specific case studies. Here, we take the next step toward a spatially explicit economically integrated water-use for energy assessment by combining a bottom-up assessment approach with a city-level multiregional input-output model. Specifically, we examine the water consumption of energy production in China, distinguishing between water for primary and secondary energy at the level of coal mines, oil and gas fields, and power plants for the first time. Of the total energy-related freshwater consumption of 4.9 Gm3 in 2017, primary energy accounted for 19% (940 Mm3) and secondary energy accounted for 81% (3955 Mm3). Coal was the largest water consumer for both primary and secondary energy (540 and 3880 Mm3, respectively), with both oil (361, and 0.5 Mm3, respectively) and gas (7 and 69 Mm3, respectively) also consuming large amounts. Intercity virtual water, that is, water embodied in energy trade across cities, reached 54% (2.6 Gm3) of energy-related freshwater consumption. Across China, 32% of cities see a bilateral trade in secondary- and primary-energy-related virtual water (e.g., Daqing city exports virtual water embodied in primary fuel to other cities that is then used to produce electricity in those cities, part of which is used back in Daqing via transmission). For these 32% of cities, 73% export more virtual water than import and 27% import more virtual water than export. This study reveals significant differences in city-level virtual water patterns (e.g., scale and direction) between primary and secondary energy to provide information for cities about their virtual water inflow and outflow and the potential collaboration partners for water management.

A sector-disaggregated cross-regional emission analysis for carbon mitigation policies from production and consumption perspectives

As one of the most challenging environment issues worldwide, climate change has posed a serious threat to habitat, species, and people's livelihoods. In this study, a sector-disaggregated cross-regional emission analysis model is developed to systematically analyze enviro-economic effects of sector-level carbon mitigation efforts from both production and consumption perspectives for supporting climate change-related policymaking. A special case study of Hubei Province, China, is conducted to demonstrate the potential benefits of its use in the climate change related policymaking field. The power generation sector has been disaggregated into five subsectors based on different power generation technologies to help investigate the potential of such technologies to carbon emission mitigations. The carbon mitigation policy scenarios from both industry optimization and demand substitute perspectives will further be explored to provide bases for decision makers to formulate the desired carbon mitigation policy aimed at different regions and sectors. Results indicate that dominant direct and indirect CO2 emissions in Hubei Province are from the Production and supply of fossil-fuel power sector and Construction sector, respectively. When industry optimization policies on the fossil-fuel power sector (in Hubei), there are significant effects on the CO2 emission mitigation whichever regions. Therefore, industry optimization policies are suggested for implementation in specific sectors with close intersectoral/interprovince trade contacts and significant emissions to achieve joint carbon emission mitigations.

Water footprint of nations amplified by scarcity in the Belt and Road Initiative

The growing water scarcity due to international trade poses a serious threat to global sustainability. Given the intensified international trade throughout the Belt and Road Initiative (BRI), this paper tracks the virtual water trade and water footprint of BRI countries in 2005-2015. By conducting a multi-model assessment, we observe a substantial increase in BRI's water footprint after taking water scarcity into account. Globally the BRI acts as a net exporter of virtual water, while the export volume experiences a decreasing trend. Noticeable transitions in nations' role (net exporters vs. net importers) are found between the BRI and global scales, but also between with and without considering water scarcity. Overall economic and population growth is major drivers of scarcity-weighted water footprint for BRI nations, as opposed to the promotion of water-use efficiency and production structure that can reduce water scarcity. Improving international trade and strengthening cooperation on water resources management deserve priority in alleviating the water scarcity of BRI.

Estimating cropland requirements for global food system scenario modeling

Introduction

The production of plant crops is foundational to the global food system. With the need for this system to become more sustainable while feeding an increasing global population, tools to investigate future food system scenarios can be useful to aid decision making, but are often limited to a calorie- or protein-centric view of human nutrition.

Methods

Here, a mathematical model for forecasting the future cropland requirement to produce a given quantity of crop mass is presented in conjunction with the DELTA Model®: an existing food system scenario model calculating global availability of 29 nutrients against human requirements. The model uses national crop yield data to assign yield metrics for 137 crops.

Results

The crops with the greatest variation between high and low yielding production were specific nuts, fruits, and vegetables of minor significance to global nutrient availability. The nut crop group showed the greatest overall yield variation between countries, and thus the greatest uncertainty when forecasting the cropland requirement for future increases in production. Sugar crops showed the least overall yield variation. The greatest potential for increasing global food production by improving poor yielding production was found for the most widely grown crops: maize, wheat, and rice, which were also demonstrated to be of high nutritional significance.

Discussion

The combined cropland and nutrient availability model allowed the contribution of plant production to global nutrition to be quantified, and the cropland requirement of future food production scenarios to be estimated. The unified cropland estimation and nutrient availability model presented here is an intuitive and broadly applicable tool for use in global food system scenario modeling. It should benefit future research and policy making by demonstrating the implications for human nutrition of changes to crop production, and conversely the implications for cropland requirement of food production scenarios aimed at improving nutrition.

Human health and ecosystem impacts of China's resource extraction

The throughput of materials fuels the economic process and underpins social well-being. These materials eventually return to the environment as waste or emissions. They can have significant environmental impacts throughout life cycle stages, such as biodiversity loss, adverse health effects, water stress, and climate change. China is the largest resource extractor globally, but the endpoint environmental impacts and the role of possible socioeconomic drivers associated with its resource extraction remain unclear. Here, we account for and analyze the two endpoint environmental impacts associated with China's resource extraction from 2000 to 2017 and quantify the relative contributions of various socioeconomic factors using structural decomposition analysis. The results show that the environmental impacts of China's resource extraction peaked in 2010. There was a significant decline from 2010 to 2017, in which human health damage decreased by 32.8 % and ecosystem quality damage decreased by 55.8 %. On the consumer side, the advancement in China's urbanization process led to an increase in the environmental impacts of urban residents' consumption, and the effect of investment on the environmental impacts decreased significantly after 2010. Decreases in the intensity of the environmental impacts in most sectors and improvements in production structure could reduce the impacts of resource extraction on human health and ecosystems.

Global spatio-temporal change assessment in interregional water stress footprint in China by a high resolution MRIO model

Developing effective strategies to alleviate increasing water stress in China requires an understanding of how consumption and production drive water stress footprints (WSF) at a high resolution and multiple spatial and temporal scales. However, current Chinese multi-regional input-output (CMRIO) models have limited resolution. Here, we build a high-resolution international MRIO model covering 31 Chinese provinces, 163 sectors, to address this issue, and then analyze the impact of changes in China's interprovincial and international trade patterns on the WSF from 2012 to 2017. We find that China's water stress embodied in inter-provincial trade has increased year after year, to 5606 km³ H₂O-eq in 2017, exceeding 50 % of the total domestic footprint. Domestic water stress transfer is most apparent in the outsourcing of water stress from eastern coastal regions to Central and Western regions, with the top interregional supply chain paths mainly associated with the demand of processed rice and tobacco products. China has transformed into a net exporter of water stress in 2017, with water stress exports to developing countries accounting for 54 % of total exports, up from 51 % in 2012. With deepening globalization, trade between China and developing countries has boosted bilateral economic development, while also exacerbating water stress in China. In addition to agricultural cultivation, industrial products such as plastics and steel exported to meet international industries further contribute to water stress in Northern China. Further identify hotspots of water stress consumption is needed to prioritize actions to relieve regional water stress in a more effective manner, and our study can provide key information.

Environmental synergies in decentralized wastewater treatment at a hotel resort

Climate change and water scarcity are clearly related environmental problems, making them global environmental issues. Accordingly, the water cycle management deserves a revision in its approach, integrating the concept of circular economy within an efficient and sustainable management of water resources and the design of wastewater facilities. In this sense, newly engineered decentralized facilities have emerged as a viable option for the treatment of segregated wastewater flows. The design has not only integrated the wastewater treatment function, but also resource recovery, such as water reclamation for agricultural and irrigation activities, fertigation, fertilization and energy sustainability. Based on these premises, the concept of decentralized wastewater management deserves the same degree of attention and development that has so far been reserved for conventional centralized management systems. Therefore, this paper proposes a progressive substitution of the business-as-usual scenario or centralized system by applying a small-scale wastewater management scheme performing a more efficient resource and water recovery in a medium-sized 4-5-star resort hotel. The spotlight was a membrane technology for the anaerobic digestion of the blackwater instead of the greywater treatment. A favorable environmental profile was found for the decentralized scenario under two circumstances: a large system boundary including the beneficial environmental impacts of the products and, based on the results obtained from a sensitivity analysis, an energy demand for the operation of the AnMBR lower than 2 kWh·m^-3. The global warming potential results (around 9%) were even for such high demand and much larger benefits were obtained for other impact categories (94% for SOD and 98% for LU). Nevertheless, the operation (gate-to-gate approach) of these on-site recovery facilities is far from being optimized and further research should follow to decrease the 39.8% difference in the global warming potential between decentralized and centralized systems.

China's Mismatch of Public Awareness and Biodiversity Threats under Economic Trade

China is one of the countries with high biodiversity on the globe, but suffers extreme biodiversity loss due to the increasingly interconnected economy. Understanding the nation-level public awareness of biodiversity under economic trades is crucial for implementing sustainable production and consumption of Sustainable Development Goals (SDGs). This study is the first to assess the public awareness of biodiversity loss associated with China's interprovincial trades by utilizing social media data and the multiregion input-output (MRIO) table. Results show that China's interprovincial trades cause heavy threats not only to local species but to distant species. Approximately 60% of provinces displace over half of their consumption-based biodiversity threats to other provinces. Nevertheless, individuals do not clearly realize their responsibility for the distant biodiversity they consumed, with a large mismatch both in popularity (Gini index = 0.51, Robin index = 39.57) and donation (Gini index = 0.69, Robin index = 54.58). To alleviate this phenomenon, our analysis suggests that the expansion of national-level nature reserves may be effectively beneficial to public biodiversity awareness, showing significantly positive partial correlation coefficients with individuals' popularity and donations. These insights provided by this study offer targeted information for conservation and call for synergistic collaboration between the civil society, especially consumers, and governments to turn the tide of biodiversity loss.

Forward-Looking Roadmaps for Long-Term Continuous Water Quality Monitoring: Bottlenecks, Innovations, and Prospects in a Critical Review

Long-term continuous monitoring (LTCM) of water quality can bring far-reaching influences on water ecosystems by providing spatiotemporal data sets of diverse parameters and enabling operation of water and wastewater treatment processes in an energy-saving and cost-effective manner. However, current water monitoring technologies are deficient for long-term accuracy in data collection and processing capability. Inadequate LTCM data impedes water quality assessment and hinders the stakeholders and decision makers from foreseeing emerging problems and executing efficient control methodologies. To tackle this challenge, this review provides a forward-looking roadmap highlighting vital innovations toward LTCM, and elaborates on the impacts of LTCM through a three-hierarchy perspective: data, parameters, and systems. First, we demonstrate the critical needs and challenges of LTCM in natural resource water, drinking water, and wastewater systems, and differentiate LTCM from existing short-term and discrete monitoring techniques. We then elucidate three steps to achieve LTCM in water systems, consisting of data acquisition (water sensors), data processing (machine learning algorithms), and data application (with modeling and process control as two examples). Finally, we explore future opportunities of LTCM in four key domains, water, energy, sensing, and data, and underscore strategies to transfer scientific discoveries to general end-users.

Development of Method for Assessing Water Footprint Sustainability

Large scale production of water-intensive industrial products can intensify water scarcity, resulting in potential unsustainable water use at local and regional scales. This study proposes a methodological framework for assessing the WF sustainability of multiple interdependent products in a system, and one of China’s four major large modern coal chemical industry bases is used as a case study. A Mixed-Unit Input-Output (MUIO) model was applied to calculate the blue water footprint (WF) for 19 major coal-based energy and chemicals in the study area, based on which the WF sustainability of production of the products were assessed using different indicators. Technical coefficient matrix and direct water consumption vector of the products were constructed based a database that were built by field research in the study area. Accounting result indicates that the blue WF of the coal-based products range from 2.5 × 10−4 m3/kWh for coal-fired power to 55.25 m3/t for Polytetrahydrofuran. The sustainability assessment reveals that the blue WF of all products produced in the study area are sustainable at both product and regional levels, while over half of them have reached the advanced level. However, the blue WF of a few products with large production capacities has just crossed the sustainable thresholds, posing potential threat to the local environment. This paper concludes with a discussion on the choice of blue WF accounting approach, methods to promote WF sustainability of coal-based products, and suggestions for the WF management in general.

Exploring the pathways towards the mitigation of the environmental impacts of food consumption

Agriculture constitutes a quarter and more than a third of Denmark's global greenhouses gas (GHG) emissions and natural resource consumption, respectively. This paper aims to estimate the potential to lower Denmark's global food-related GHG, blue water and land footprints using the most recent version of a hybrid global multi-regional input-output (MRIO) database, EXIOBASE of the reference year, 2011. Specifically, we apply the 'what if' scenario-based MRIO approach to EXIOBASE and quantify the impact of increased livestock feed efficiency (FE), dietary changes, food loss and waste (FLW) reduction/prevention and food waste treatment scenarios on Denmark's global food-related GHG and resource footprints. We obtain modest reductions in Denmark's global food-related GHG, blue water and cropland footprint from the combination of livestock FE improvements and FLW reduction; 61 kt CO₂e, 2 Mm³ and 30 kha, respectively. In contrast, dietary change towards no/less meat and dairy diets embodies the most significant reductions potential for Denmark's total global food-related GHG, blue water, croplands and grassland footprint by up to 34% (3.63 Mt. CO₂e), 8% (90 Mm³), 23% (371 kha) and 78% (386 kha) respectively. A key policy priority should therefore be the nudging of Danish consumers towards sustainable diets. Also, this study's findings emphasise that FLW prevention remains the most effective food waste-related climate mitigation and resource efficiency strategy despite the benefits of food waste valorisation.

Cascading costs of snow cover reduction trend in northern hemisphere

Environmental changes in response to global warming would conversely deplete the efficacy of our actions combating climate change, cultivating extra cost. Among them, the declining snow cover due to global warming would diminish its contribution to climate regulation, and further exacerbate global warming. This leads to a part of global carbon mitigation efforts acting virtually to neutralize the impact of snow cover reduction. It would have been otherwise saved to contribute to the goals of the Paris Agreement. In this respect, here we evaluate the economic impacts of snow cover reduction in the Northern Hemisphere in terms of the mitigation that virtually counteracts the loss of climate regulation pertinent to the snow cover reduction trend, to demonstrate the magnitude of the cascading costs of climate change. As different carbon mitigation approaches would lead to different economic impacts, we follow the general principles of the Paris Agreement and establish two responsibility-sharing scenarios. The results reveal the non-negligible global costs considering not only the impact incurred by the nations implementing carbon mitigation but also, in the context of globalization, the cascading effect magnified in the global supply chain. We also identify critical nations, sectors, and international trade pairs that would confront the most costs. The results urge hotspot nations and trade partners to actively participate in the enhanced global efforts through the Paris Agreement to reduce carbon emissions. This can not only mitigate its direct global warming effect, but also abate the impacts of collateral environmental deterioration, such as snow cover reduction, eventually for their own benefits.

Water pollutant discharge permit allocation based on DEA and non-cooperative game theory

Against the background of the ecological civilization system reform in the new era, the appropriate allocation of water pollutant discharge permits is an important policy for controlling the amount of wastewater discharge. Traditional allocation methods have disadvantages, such as high additional costs, an unfair allocation scheme, and market distortion. In the present study, a fixed-cost allocation model based on data envelopment analysis (DEA) and the Nash non-cooperative game theory is employed to allocate water pollutant discharge permits of totally 31 provinces in China from 2008 to 2017. The allocation scheme considers environmental efficiency. The results demonstrate regional differences in the allocation of water pollutant discharge permits. The eastern region has abundant allocations. The northeastern and central regions have insufficient allocations. Besides, the western region has a significant shortage of allocations. It indicates the higher the utilization efficiency of the water pollutant discharge permits, the higher the region's sustainable development is. Based on the analysis, we propose guidelines for industrial wastewater discharge reduction.

Integrated modelling to assess the impacts of water stress in a transboundary river basin: Bridging local-scale water resource operations to a river basin economy

In this study, we develop a hydro-economic modelling framework for river-basin scales by integrating a water resources system model and an economic model. This framework allows for the representation of both local-scale features, such as reservoirs, diversions, and water licenses and priorities, and regional- and provincial-scale features, such as cross-sectoral and inter-regional connectedness and trade flows. This framework is able to: (a) represent nonlinearities and interactions that cannot be represented by either of typical water resources or economic models; (b) analyze the sensitivity of macro-scale economy to different local water management decisions (called 'decision levers' herein); and (c) identify water allocation strategies that are economically sound across sectors and regions. This integrated model is applied to the multi-jurisdictional Saskatchewan River Basin in Western Canada. Our findings reveal that an economically optimal water allocation strategy can mitigate the economic losses of water stress up to 80% compared to the existing water allocation strategy. We draw lessons from our analysis and discuss how integrated inter-regional hydro-economic modelling can benefit vulnerability assessment and robust decision making.

Identifying optimal virtual water management strategy for Kazakhstan: A factorial ecologically-extended input-output model

Virtual water is an important indicator measuring the amount of water needed from the perspective of consumption, which can help decision makers to identify desired system design and optimal management strategy against water resources shortage. In this study, a novel model named as factorial ecologically-extended input-output model (abbreviated as FEIOM) is developed for virtual water management. FEIOM integrates techniques of input-output model (IOM), ecological network analysis (ENA) and factorial analysis (FA) into a general framework. It is effective to evaluate the virtual water flows, reveal ecological inter-connections in virtual water system (VWS), and identify key water consumption sectors that have significant individual and interactive effects on VWS's performance. FEIOM is then applied to identifying optimal virtual water management strategies for Kazakhstan in Central Asia. The main findings are: (i) Kazakhstan is a net importer of virtual water (reaching up to 46.0 × 10⁹ m³), demonstrating that the national economic structure is reasonable, which can abate the national water scarcity and improve its eco-environmental protection; (ii) the virtual water of agricultural sector is net exporter, where vegetables, fruits and nuts occupy 86% of the total agricultural exports; the massive export of water-intensive products further squeezes the water for other users; (iii) the key factors affecting the national VWS are agriculture > primary manufacturing > advanced manufacturing > services. Therefore, from solving water resources shortage and facilitating sustainable development perspectives, Kazakhstan should stimulate the domestic primary manufacturing productions and improve agriculture and advanced manufacturing water-use efficiencies.

Unveiling the dynamic of water-electricity conflict within and beyond megacity boundary

Electricity demand in megacities may exert substantial stress on water resources, which is often expressed through the water scarcity footprint for electricity consumption (WSFE). Conversely, water scarcity may constrain electricity production, leading to increased vulnerability for megacities electricity production. The WSFE and the water related vulnerability of electricity production reflect two aspects of water-electricity conflict. This varies over time by both the amount and location of electricity production. However, no studies have conducted time-series analysis to evaluate the trends of these two indicators, both in terms of severity and spatial characteristics. Our study focused on evaluating trends in water-electricity conflict both within and beyond megacity administrative boundaries. China's four provincial-level megacities, i.e. Beijing, Tianjin, Shanghai and Chongqing, were chosen as case studies. The results show that water related vulnerability of electricity production in Tianjin, Beijing, Shanghai and Chongqing was diverse and can be classified as extreme, severe, moderate and minor, respectively. Between 2006 and 2016, the WSFE of Tianjin experienced an increasing trend, and its water related vulnerability of electricity production remained at the highest level. Beijing's WSFE has decreased, but its water related vulnerability of electricity production has increased. These differing trends highlight the need for joint reductions to both WSFE and water related vulnerability of electricity production in mitigating water-electricity conflict.

Evaluating the carbon footprint of a Spanish city through environmentally extended input output analysis and comparison with life cycle assessment

Currently, most of the greenhouse gas (GHG) emissions are attributed to cities, as they are the global centers of business, residential and cultural activity, cities are expected to play a leading role in proposing climate change mitigation actions. To do so, it is important to have tools that allow the carbon footprint of cities to be assessed as accurately as possible. This study aims to quantify the carbon footprint (CF) associated with the activities developed in a Spanish city (Cadiz, Southwest Spain) by means of two available environmental methodologies, namely Environmentally Extended Input-Output Analysis (EEIOA) and Life Cycle assessment (LCA). When EEIOA is considered, two downscaling factors were proposed for the analysis due to the nature of the data handled (monetary data), based on the incomes (DF₁) and expenditures (DF₂) per inhabitant at city level. Regarding LCA, the rates of consumption of goods and production of waste per inhabitant have been processed to estimate the CF. The CF scores identified were 5.25 and 3.83 tCO₂-eq·inhabitant^-1·year^-1 for DF₁ and DF₂ respectively, according to EEIOA, and 5.43 tCO₂-eq·inhabitant^-1·year^-1, considering LCA. Therefore, a similarity can be concluded between the results obtained with both methodologies despite the inherent differences. Considering the results, the downscaling procedure based on income per inhabitant should be preferred, pointing to EEIOA as a good alternative to LCA for evaluating the CF at city level, requiring less time and effort. In contrast, EEIOA reports more limitations when critical flows were identified, which LCA can solve. Finally, this study can be of great interest to policy makers and city governments to know the CF and the main flows that contribute and in this way, can develop new policies and city models for reducing GHG emission new policies and city models for reducing GHG emission and addressing climate change.

An assessment of the water use associated with Australian diets using a planetary boundary framework

OBJECTIVE

Agriculture accounts for around 70 % of global freshwater withdrawals. As such, the food system has been identified as a critical intervention point to address water scarcity. Various studies have identified dietary patterns that contribute less to water scarcity. However, it is unclear what level of reduction is necessary to be considered sustainable. The pursuit of unnecessarily aggressive reductions could limit dietary diversity. Our objective was to assess the sustainability of water use supporting Australian dietary habits and the adequacy of current dietary guidelines.

DESIGN

Dietary intake data were obtained from the National Nutrition and Physical Activity component of the Australian Health Survey. For each individual daily diet, the water scarcity footprint was quantified, following ISO14046:2014, as well as a diet quality score. Water scarcity footprint results were compared with the planetary boundary for freshwater use downscaled to the level of an individual diet.

SETTING

Australia.

PARTICIPANTS

9341 adults participating in the Australian Health Survey.

RESULTS

Dietary water scarcity footprints averaged 432·6 L-eq (95 % CI 432·5, 432·8), less than the 695 litres/person per d available to support the current global population of 7·8 billion, and the 603 litres/person per d available for a future population of 9 billion. Diets based on the Australian Dietary Guidelines required 521 L-eq/d, or 379 L-eq/d with lower water scarcity footprint food choices.

CONCLUSIONS

Diets based on the Australian Dietary Guidelines were found to be within the freshwater planetary boundary. What is needed in Australia is greater compliance with dietary guidelines.

Pesticide Toxicity Hazard of Agriculture: Regional and Commodity Hotspots in Australia

While the need to reduce the impacts of pesticide use on the environment is increasingly acknowledged, the existing data on the use of agricultural chemicals are hardly adequate to support this goal. This study presents a novel, spatially explicit, national-scale baseline analysis of pesticide toxicity hazard (the potential for chemicals to do harm). The results show an uneven contribution of land uses and growing regions toward the national aggregate toxicity hazard. A hectare of horticultural crops generates on average ten times more aquatic ecotoxicity hazard and five times more human toxicity hazard than a hectare of broadacre crops, but the higher yields and incomes in horticulture mean that both sectors are similar in terms of environmental efficiency. Livestock is the sector with the least contribution to overall hazard, even when the indirect hazard associated with feed is considered. Metrics such as pesticide use (kg/ha) or spray frequency (sprays/ha), commonly reported in highly aggregated forms, are not linearly related to toxicity hazard and are therefore less informative in driving reductions in impact. We propose toxicity hazard as a more suitable indicator for real-world risk than quantity of pesticide used, especially because actual risk can often be difficult to quantify. Our results will help broaden the discussion around pathways toward sustainability in the land-use sector and identify targeted priorities for action.

Integrated virtual water trade management considering self-sufficient production of strategic agricultural and industrial products

The uneven distribution of water on earth causes its scarcity in many countries, hindering economic and human development. Virtual water trading takes place by the export and import of agricultural and industrial products whose production involves water and, so, is one of the methods to cope with water scarcity. This work investigates the integrated management of the virtual water trade of strategic agricultural and industrial products with the goals of maximizing economic revenue and minimizing the consumption of virtual water. Bi-objective optimization is performed with the non-dominated sorting genetic algorithm (NSGA)-II algorithm under two scenarios. One of the scenarios applies production constraints to ensure a minimum of internal or domestic production of agricultural and industrial goods, thus providing a degree of self-sufficiency. This paper applies its methodology to Iran and establishes that the imports of industrial products should be terminated and exports of these products should increase. The results show that the export amount of iron ore increases by 71% due to the application of the self-sufficiency constraint, which shows the profitability of this product in addition to its low water consumption. This paper demonstrates that the optimal solutions for agricultural products (except for potatoes and tomatoes) is achieved by producing at least 50% of the domestic demand, but rarely calls for a higher level of production. This work illustrates through the case study that it is possible to increase economic revenue under water scarcity by proper management of the virtual water trade.

Exploring consumption-based planetary boundary indicators: An absolute water footprinting assessment of Chinese provinces and cities

The water planetary boundary (PB) has attracted wide academic attention, but empirical water footprint research that accommodates local biophysical boundaries remains scarce. Here we develop two novel quantitative footprint indicators, the water exceedance footprint and the surplus water footprint. The first measures the amount of excessive water withdrawal (exceeded amount of water withdrawn against local water PBs) and the latter evaluates the potential of surplus water that can be sustainably utilised (amount of surplus water available within local water PBs). We quantify the extent to which demand for goods and services in Chinese provinces and cities are driving excessive withdrawal of local and global water resources. We investigate both territorial and consumption-based water withdrawal deficit and surplus against local water withdrawal PBs. We also trace how PB-exceeded water and surplus water are appropriated for producing certain commodities. In 2015, China's domestic water exceedance reaches 101 km³ while the total water exceedance footprint is 92 km³. We find that 47% of domestic excessive water withdrawal is associated with interprovincial trade. Exceeded water transfers were dominated by agricultural trade from the drier North to the wetter South. A revised virtual water trade network informed by exceedance and surplus water footprint metrics could help address sustainability concerns that arise from the trade of water-intensive commodities. Our findings highlight that policy targets need to accommodate PB exceedance of both direct and virtual water use.

Unlocking the Impacts of COVID-19 Lockdowns: Changes in Thermal Electricity Generation Water Footprint and Virtual Water Trade in Europe

Drastic changes in electricity demand have been observed since March 2020 in Europe, after several countries implemented lockdown-like measures to contain the spread of COVID-19. We investigate the sensitivity of the electricity-water nexus in the European electric grid to large-scale behavior changes during the COVID-19 pandemic lockdown-like measures. We quantify changes in the blue virtual water trade between five European countries heavily affected by COVID-19 during the same period. As a result, the consumptive water footprint of thermal power plant operations in Europe decreased by 1.77 × 106 m3/day during the COVID-19 lockdowns, compared to the average of the past four years. Reduced electricity demand accounts for 16% (0.29 × 106 m3/day) of the decrease, while the remainder is attributable to changes in the electricity generation mix toward less water-intensive technologies before 2020 and during lockdowns. Virtual water transfers associated with electricity were also affected: Italy, a hotspot of COVID-19, reduced its water footprint by 8.4% and its virtual water imports by 70,700 m3/day. Germany and France slightly reduced their domestic water footprint of electricity but increased their virtual water imports. These findings improve our understanding of the impacts of large-scale behavior and technological changes to the European electricity-water nexus.

What Factors Drive the Changes in Water Withdrawals in the U.S. Agriculture and Food Manufacturing Industries between 1995 and 2010?

Climate change and increasing world population will directly impact the global food supply chain linkages. In the United States, agricultural production requires less irrigated water than before but it still accounts for a third of total water withdrawals. To better understand the evolution of its water use, we perform a structural decomposition analysis of water withdrawals across eight different crops and six livestock categories and differentiate the trends over 1995-2005 vs 2005-2010 to account for the role of the economic crisis in the second period. Based on USGS data, the results show that both periods experienced an overall decline in water withdrawals in the production of all crops except oilseeds. This trend is driven by a decrease in water intensity, reflecting greater efficiency of irrigation systems, and by reduced local per capita income in the second period. However, increased foreign demand for water-intensive sectors like oilseeds from NAFTA and Asian partners mitigated the decline. Results indicate also a decreasing water use in livestock production partially due to a shift from red to white meat consumption in the country. Arguably, recent tariff wars and border closures have greatly reduced the virtual water embodied in American exports.

Drivers of Water Use in the Agricultural Sector of the European Union 27

Population growth and the uncertain hazards that accompany climate change have put increasing pressure on the management and sustainability of water. It has a direct impact on agriculture and its domestic and international supply chain linkages. As one of the largest agricultural producers in the world, the European Union (EU) is particularly sensitive to changes in water availability. Therefore, we perform a structural decomposition analysis based on the recently released EXIOBASE 3 database to examine in depth how changes in water input coefficients, in final demand and in technology have affected changes in water use across crops. Crop production consumes 99% of the direct water in agriculture. Our results show that the largest EU crop producers have experienced an increase in water use that is mostly driven by changes in technology. On the other hand, several Mediterranean countries, where water scarcity has been a problem for years, have decreased their water consumption mostly thanks to an improvement in their water intensity. Results by crop are consistent with those at the aggregated level except for vegetables of which water use changes have been primarily driven by changes in final demand and water intensity.

An Analysis of the Cost of Water Supply Linked to the Tourism Industry. An Application to the Case of the Island of Ibiza in Spain

Tourist activity has a number of impacts on the destinations in which it takes place, among which are the environmental ones. A particular problem is the increase in water demand and wastewater production, which can compromise the balance of ecosystems. As many authors point out, there is a research gap in the comparative analysis between available water resources and the demand associated with tourism. In this respect, the main objective of this work is, on the one hand, to assess the water needs linked to the tourism industry and the capacity of natural resources to meet such a demand and, on the other hand, to estimate the economic cost of the water supply associated with the growing tourist demand in a territory, such as the island of Ibiza in Spain. It has been determined that the resources available are not sufficient to meet the water demand of the resident population at this destination, which is why it is necessary to resort to producing desalinated water. Therefore, the additional requirements associated with tourism must be met fully with desalinated water, which results in an increased cost of water management for the region. This paper also points at water losses in distribution networks and tourism seasonality as two phenomena that aggravate this issue.

Effects of Spatial Scale on Life Cycle Inventory Results

Efforts to compile life cycle inventory (LCI) data at more geographically refined scales or resolutions are growing. However, it remains poorly understood as to how the choice of spatial scale may affect LCI results. Here, we examine this question using U.S. corn as a case study. We compile corn production data at two spatial scales, state and county, and compare how their LCI results may differ for state and national level analyses. For greenhouse gas (GHG) emissions, estimates at the two scales are similar (<20% of difference) for most state-level analyses and are basically the same (<5%) for national level analysis. For blue water consumption, estimates at the two scales differ more. Our results suggest that state-level analyses may be an adequate spatial scale for national level GHG analysis and for most state-level GHG analyses of U.S. corn, but may fall short for water consumption, because of its large spatial variability. On the other hand, although county-based LCIs may be considered more accurate, they require substantially more effort to compile. Overall, our study suggests that the goal of a study, data requirements, and spatial variability are important factors to consider when deciding the appropriate spatial scale or pursuing more refined scales.

Enabling Full Supply Chain Corporate Responsibility: Scope 3 Emissions Targets for Ambitious Climate Change Mitigation

There is building consensus that nonstate actors have the potential to drive more ambitious action toward climate targets than governments, thus driving the necessary transition to ensure that humanity remains within a safe operating space. These bottom-up mitigation activities, however, require individual targets on both direct and indirect (upstream) greenhouse gas (GHG) emissions in order to reconcile trade-offs between global and local sustainability goals. Here we use a scenario-driven approach based on a global multiregional input-output (GMRIO) model to develop scope 3 emission reduction targets for individual economic sectors, comparable across countries and geographies. Under an ambitious carbon mitigation scenario for 2035 (that follows a trajectory of 1.75 °C total warming by 2100), global upstream scope 3 emission intensities need to be reduced by an additional 54% compared to a baseline scenario with reference technology. On a sectoral basis, this is equivalent to a 58-67% reduction in energy, transport, and materials, a 50-52% reduction in manufacturing, services, and buildings, and a 39% reduction in agriculture, forestry, and other land use. By aligning indirect supply chain targets with ambitious carbon mitigation scenarios, our approach can be used by nonstate actors to set actionable scope 3 targets and to build climate-compatible business models.

How to allocate discharge permits more fairly in China?-A new perspective from watershed and regional allocation comparison on socio-natural equality

Equitable and efficient allocation of pollutant discharge permits is vital for controlling total pollutant amounts. However, the conventional water pollutant discharge permit allocation method is criticized for dividing the environmental attributes of water bodies, which is mainly based on administrative units. China is establishing a water ecological environment zoning management system to manage the water environment more scientifically, which may have a great impact on for controlling total pollutant amounts. Whether the ecological environment zoning management system can promote more equitable and efficient permit allocation remains unknown. In this paper, an environmental zoning system and "basin-region" correlation are established to take both regional and watershed allocation processes into consideration. Then, a multi-index Gini coefficient method is established to evaluate the equality of different allocating methods. The Gini coefficient is then combined with a linear interactive and general optimizer method to achieve an equitable allocation of ammonia nitrogen discharge permits in the Songhua River Basin from both watershed and regional perspectives. Forty-five water pollutant discharge allocation scenarios are considered to represent different manager tendencies. The results show that allocation based on watershed functional units is more equitable than that based on administrative units. The index weighting settings also have a large impact on regional and total equality and environmental efficiency. Midstream and downstream areas show large allocation differences, although no scenario can satisfy all watershed regions in terms of equality and environmental efficiency at the same time. Thus, more trade-offs are needed during decision making. By considering the coordination of social, environmental and economic development at the basin level, this study provides new insight into equitable and efficient allocation. Moreover, the findings suggest that an environmental zoning system should be considered for discharge permit allocation in water resource management.

Cold Atmospheric Plasma as a Novel Method for Inactivation of Potato Virus Y in Water Samples

While one of the biggest problems we are facing today is water scarcity, enormous quantities of water are still being used in irrigation. If contaminated, this water can act as an effective pathway for the spread of disease-causing agents, like viruses. Here, we present a novel, environmentally friendly method known as cold atmospheric plasma for inactivation of viruses in water used in closed irrigation systems. We measured the plasma-mediated viral RNA degradation as well as the plasma-induced loss of viral infectivity using potato virus Y as a model virus due to its confirmed water transmissibility and economic as well as biological importance. We showed that only 1 min of plasma treatment is sufficient for successful inactivation of viruses in water samples with either high or low organic background. The plasma-mediated inactivation was efficient even at markedly higher virus concentrations than those expected in irrigation waters. Obtained results point to reactive oxygen species as the main mode of viral inactivation. Our laboratory-scale experiments confirm for the first time that plasma has an excellent potential as the eukaryotic virus inactivation tool for water sources and could thus provide a cost-effective solution for irrigation mediated plant virus transmission. The outstanding inactivation efficiency demonstrated by plasma treatments in water samples offers further expansions of its application to other water sources such as reused wastewater or contaminated drinking waters, as well as other plant, animal, and human waterborne viruses, ultimately leading to the prevention of water scarcity and numerous human, animal, and plant infections worldwide.

Diet Quality and Water Scarcity: Evidence from a Large Australian Population Health Survey

There is widespread interest in dietary strategies that lower environmental impacts. However, various forms of malnutrition are also widely prevalent. In a first study of its kind, we quantify the water-scarcity footprint and diet quality score of a large (>9000) population of self-selected adult daily diets. Here, we show that excessive consumption of discretionary foods—i.e., energy-dense and nutrient-poor foods high in saturated fat, added sugars and salt, and alcohol—contributes up to 36% of the water-scarcity impacts and is the primary factor differentiating healthier diets with lower water-scarcity footprint from poorer quality diets with higher water-scarcity footprint. For core food groups (fruits, vegetables, etc.), large differences in water-scarcity footprint existed between individual foods, making difficult the amendment of dietary guidelines for water-scarcity impact reduction. Very large reductions in dietary water-scarcity footprint are possible, but likely best achieved though technological change, product reformulation and procurement strategies in the agricultural and food industries.

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.

Going Global to Local: Connecting Top-Down Accounting and Local Impacts, A Methodological Review of Spatially Explicit Input-Output Approaches

Environmentally Extended Input-Output Databases (EEIOs) provide an effective tool for assessing environmental impacts around the world. These databases have yielded many scientific and policy relevant insights, especially through the national accounting of impacts embodied in trade. However, most approaches average out the spatial variation in different factors, usually at the level of the nation, but sometimes at the subnational level. It is a natural next step to connect trade with local environmental impacts and local consumption. Due to investments in earth observation many new data sets are now available, offering a huge potential for coupling environmental data sets with economic models such as Multi-Region Input-Output (MRIO) models. A key tool for linking these scales are Spatially Explicit Input-Output (SIO) models, which provide both demand and supply perspectives by linking producers and consumers. Here we define an SIO model as a model having a resolution greater than the underlying input-output transaction matrix. Given the increasing interest in this approach, we present a timely review of the methods used, insights gained, and limitations of various approaches for integrating spatial data in input-output modeling. We highlight the evolution of these approaches, and review the methodological approaches used in SIO models so far. We investigate the temporal and spatial resolution of such approaches and analyze the general advantages and limitations of the modeling framework. Finally, we make suggestions for the future development of SIO models.