One Earth, Journal Year: 2020, Volume and Issue: 2(3), P. 218 - 222

Published: March 1, 2020

Widespread water scarcity, pollution, and depletion of freshwater resources are among the grand environmental challenges 21st century related to water. Central these is fact that humanity uses too much But what we using all for? The footprint concept can help answer this question, more. Addressing relation between human consumption water's challenges, resonates with stakeholders within beyond walls science. This Primer describes basics concept, how it works, why came about. Drawing from recent studies in new research field Water Footprint Assessment, highlights some intriguing applications delves into next on exciting interdisciplinary agenda. Freshwater a finite vulnerable resource, essential sustain life, development, environment. However, despite its readily acknowledged importance, way has managed—and continues manage—its precious led number Numerous river basins worldwide facing scarcity. Many bodies polluted sorts substances, stocks both surface groundwater depleted many places around world. As consequence, ecosystems soils have degraded, sometimes repair. Species depend losing their habitat going extinct at alarmingly high rates. Finally, vulnerability systems (climate) shocks increased dramatically. main drivers for overuse pollution rivers, lakes, population growth economic development. More people means more goods services require production, wealthier typically consume per person. Specifically, when affluence rises, tend shift toward diets contain animal products. Omnivorous generally intensive produce than vegetarian diets. Climate change also affecting use resources, as warmer temperatures, erratic rainfall, extreme weather events raise demand by farmers, industries, households, power producers. While science policy discussions often dominated concerns over role impact climate change, important note our current crises best explained growing populations water-intensive services. Even if manage reduce or prevent additional negative effects happening, humanity's unquenchable thirst will continue rise exceed environmentally sustainable thresholds. transcend domain societal realms. Competition (access to) limitedly available various users been linked inequality marginalized user groups, conflict—sometimes even violent conflict— migration. If businesses farmers cannot meet crops, deepening insecurity food energy looming. World Bank, others, repeatedly warns significant stalling development because shortages (clean) freshwater, Economic Forum lists consistently one largest global risks terms impact. Although there say about causes consequences crises, clear polluting activities comes cost nature communities, be sustained future. Solving thus calls considerable bridling consumption. A question naturally arises, then, where in. At base, (WF) multidimensional indicator volumetric pollution. Whereas traditional indicators such abstraction withdrawals report (gross) volumes taken body, WF indicates (net) consumption, which explicitly links beneficiary activity (e.g., potato washing car). Consumption refers "lost" system, therefore used other purposes particular time location. In words, appropriation time- location-specific manner. Next, includes connotation source water, represented green, blue, gray color components. green rainfall melted snow stored root zone soil evaporates back atmosphere. particularly relevant agricultural forestry products evaporation plants trees. blue sourced either evaporated incorporated product. consumed irrigated agriculture, industry, households amount needed assimilate pollutants associated local water-quality standards. measures natural resource (via WF) an agent waste WF). unites quantity quality indicator. WFs calculated base unit process activity. These summed product, company, sector, consumer level (Figure 1). aggregated representations, considers direct indirect use, meaning accounts along each step value chain. investigated wide variety processes, products, sectors. Let me give somewhat random yet telling anthology. We now know takes 1,200 L pizza Margherita (on average, summing ingredients pizza), 3,200 pair cotton jeans (summing dying sewing fabric), 14,600 gigajoule generated hydropower. average person Earth needs 3,800 day support his her lifestyle, most food. diet up 40% less omnivore. Agriculture 92% WF, while remainder roughly equally split industry household use. Of nearly 10,000 billion cubic meters year consumes across sectors, 74% 11% 15% Insightful are, onset was designed encompass "just" Both character described above broader framework shown Figure 1 emerged good reasons. First, insight not only but resource. Through trade international markets, virtually traded too. It "embedded" Via trade, buyers consumers effect make elsewhere. What more, allocation authorities increasingly driven dynamics economy. Acknowledging dimension opened niche studying (footprints) globalization. Despite however, impacts remain largely local. Since renewal rates limited, second notion need studied context geographical boundaries ecological limits. contextualization appropriate (local) settings helps "so what?" large small WF. Comparing availability levels reveals pressure placed systems. Doing so makes meaningful actionable solving third driver instrumental outside multinational companies learned they wanted assess production perspective (recall study supply chains and—perhaps importantly—to Global Assessment Standard (Hoekstra et al., 2011Hoekstra A.Y. Chapagain A.K. Aldaya M.M. Mekonnen Manual: Setting Standard. Earthscan, 2011Google Scholar). widely adopted method, four steps practitioners academics alike systematically: (1) scope assessment; (2) accounts; (3) place sustainability contexts; (4) propose (policy-relevant) response options. Over decade passed since publication standard, transformed scientific discourse called Assessment. section explores were undertaken budding field. first application answering I started with: analysis, accounting, made resonate general public widening community particular. explored processes commodities, ranging empirical case high-resolution modeling level. showed linking us understand amounts being allocated—often implicitly—to food, feed, fuel, fibers. provides systematic language express units (cubic meters) (tons produce) (joules calories), example, enables researchers designing carbon neural mixes mix. Hydropower, turned out, bioenergy moreover may compete production. separate treatment sourcing emphasized importance Green granted overlooked water-management deal (irrigation) only. same time, combining (green WFs) (gray laid bare inevitable trade-offs two For boosting crop yield adding fertilizers green-blue reduced, increase leaching out excessive bodies. Spatial variations facilitated analyses efficient similar soils, climatic conditions, farming practices, found major differences other. Reducing inefficiencies substantial water-saving potential directly contribute challenges. earlier order interpret way, contextualized setting. Comprising assessment according Standard, compared levels. From hydrological learn where; ecologists hear reserved nature. remains then sustainably appropriated humans. maximum levels, scarcity results. Likewise, fertilizers, pesticides, pharmaceuticals) added body assimilate, mapped periods Worldwide, estimated live regions face least month year. half overexploited, fertilizer leaching. Because underlying assessments identifying contributions specific detrimental informs producers, consumers, makers effectively practically target reduction efforts. Other presented focus To calculate aggregate 1), flows unearthed. Tracing globally interwoven lays producers consumers. 2, shows virtual countries result industrial commodities. Green-colored export form import. Yellow red countries, contrary, foreign needs. Such water-flow reveal interdependencies again (trade in) illustrates become truly geopolitical green-colored exported larger imported, making them net importers. opposite goes yellow- red-colored exporters. Reproduced Hoekstra Mekonnen, 2012Hoekstra humanity.Proc. Natl. Acad. Sci. U S A. 2012; 109: 3232-3237Crossref PubMed Scopus (1100) Google Scholar. Recognizing political aspects, governments (particularly dryer Middle East North Africa) utilize explore unavoidable dependency (possibly unstable) partners certain key inform national security strategies. Likewise businesses, tracing could potentially harm operations, well operations themselves might generate individuals component. Various lifestyles supported external resources. typical Dutch externalized 95% though Netherlands relatively water-rich country self-sufficient. part unsustainable, almost lies already affected show traced product originates from. Several proposed concrete recommendations address setting caps basin promising measure ensure total stays boundaries. Designed achieve limit permits issue demanding without harming Formulating benchmarks water-using another suggestion, aimed achieving benchmark reference reasonable producer benchmark, apparently wasting needlessly 3). Adopting practices benchmark. imply changing inundating entire irrigate drip irrigation provide just enough plant roots. transitioning closed-loop treated reused factory's fence. set 25th percentile would wheat reduced 39%. Hoekstra, 2014Mekonnen production: assessment.Ecol. Indicators. 2014; 46: 214-223Crossref (186) Combining recommendations, managers until cap, those Elements starting find actual policies, Spain incorporate drafting plans. Preliminary attempts fair shares equitable inclusive efforts, before practical made. comprehensive overview please see 2017Hoekstra (WFA): evolvement field.Water Resour. Manag. 2017; 31: 3061-3081Crossref (122) any forms rapidly. Given severity interest expected grow. literature date, emphasis accounting flows. detailed maps, series, data developed activity, pollutants, properties, statistics, input further improve. WFs. Improved understanding granularity models, flow methods, better evaluate contexts. date literature, formulating options unsustainable underemphasized. gap—and opportunity—remains tested location during period, transferrable settings? How global? "water" solution policy, people's habits diets? Or level, play—water makers, investors? member family footprints, including land, carbon, material footprints. Future extent differing methodologies behind footprints synthesized otherwise aligned, example do trade-off pursuing smaller vice versa, whether perhaps true time. Additional lines inquiry revolve water-for-energy water-for-food studies—for reaching UN's Sustainable Development Goals energy. Potential questions are: Is transition neutral mixes? hydropower requirements future? given constraints? versus extensive management policies WF? smart, precision, urban agriculture food? feed 10 Earth's planetary boundary use? Also under change? comprises (a right minimum consumption? illustrate fundamental integrative Their breadth width underscore applied disciplines subsets thereof, nexus footprinting studies. urgent shared responsibility. actors science-policy-action interface, informing academics, business people, understand, frame, respond looming crises. holds great emerge. challenge you advance your future Large parts content based substantive oeuvre Prof. Dr. Arjen who introduced 2002 helped mature ever since. On November 18, 2019, he suddenly unexpectedly away soon. visionary world through thinking. many, myself, still grieving loss colleague, mentor, friend, trust legacy grow topics touches ever. dedicate piece him. partially funded European Research Council Union's Horizon 2020 Innovation Programme ([email protected] project grant agreement no. 834716).

Language: Английский