Exploring consumption-based planetary boundary indicators: An absolute water footprinting assessment of Chinese provinces and cities
Graphical abstract
Introduction
Absolute sustainability assumes that natural capital stocks are not substitutable and that human activities must always remain within the carrying capacity of natural capital (Meadows et al., 1972). The idea of revisiting carrying capacity of natural capital has gained momentum in the scientific community. The planetary boundaries (PBs) framework, formulated by Rockström et al. (2009) and recently updated by Steffen et al. (2015b) proposes absolute biophysical limits that delineate a safe operating space for human prosperity at the global level by quantifying collective human modifications of the Earth system in the Anthropocene (Steffen et al., 2015a). While the global freshwater use PB has not been exceeded, many regional boundaries have been exceeded or are increasingly under threat (Lade et al., 2019). Current unsustainable patterns of freshwater use exert pressure on a number of highly stressed watersheds and basins (Mekonnen and Hoekstra, 2016; Motoshita et al., 2020). Since 2009, absolute water PB thresholds have been proposed by the academic community (Bogardi et al., 2013; Falkenmark et al., 2019; Gerten et al., 2013, 2020; Gleeson et al., 2020b; Jaramillo and Destouni, 2015).
The wide uptake of water footprint studies in recent years highlights their increasingly recognised policy relevance (Hoekstra and Mekonnen, 2012; Hoekstra and Wiedmann, 2014). Environmental footprints in general are becoming an indispensable dimension in analysing PB-related research questions as they link global production and consumption patterns to biophysical limits (Häyhä et al., 2016; Laurent and Owsianiak, 2017). The key strengths of footprint studies are their ability, in a world of trade, to encompass all upstream environmental implications of the consumptive use of natural resources, as well as to examine the inequalities and interdependencies across borders (Wiedmann and Lenzen, 2018). Virtual water trade (i.e. water scarce regions import water-intensive products to conserve local water resources) is seen as a measure to alleviate pressure on scarce water resources, to improve overall water use efficiency and to future-proof domestic water and food security (Hogeboom, 2020).
We argue that in order to enable absolute water footprinting assessment, a logical and necessary step is to incorporate local water PBs into water footprint accounting. It is the additional water extracted above a threshold that must be avoided from an absolute sustainability perspective, as this would give rise to exceedance which significantly increases the probability of local ecological impacts (Gerten et al., 2015, 2020; Gleeson et al., 2020b). Understanding which economic sectors or commodities create water exceedance indirectly along a given supply chain is essential (Li et al., 2019). The embodied part of the water footprint may often lead to exceedance of local water PBs somewhere far away from the point of consumption. This absolute sustainability perspective conveys environmental risk in a much more explicit manner compared to conventional water footprint assessments which typically encompass water thresholds in one of two ways. They either account for local water thresholds by multiplying water use with water scarcity characterisation factors in order to calculate a stress-normalised measure of water use (Chenoweth et al., 2014; ISO, 2014). This method is useful for seeking relatively more sustainable options based on overall scarcity contributions, as determined through universally applied thresholds, but does not fully encompass absolute sustainability thresholds because the degree of biophysical exceedance is not explicitly quantified (Liu et al., 2017; Ridoutt et al., 2018; Wang and Zimmerman, 2016). Alternatively, recent approaches also directly compare footprint results with local water thresholds in absolute terms (often on a per capita basis) (Dao et al., 2018; Lucas and Wilting, 2018; Nykvist et al., 2013; O’Neill et al., 2018). This latter approach tends to be more suited to globally relevant (e.g. carbon footprint) indicators that do not require a locally-specific threshold, and will only provide aggregated consumption-based impacts thus missing location-specific impacts allocation along the supply chain and effective intervention points.
Empirical consumption-based water footprint research that measures the extent of transgression and regional allocation of the locally-specific water PB control variable remains underexplored. The purpose of this paper is to introduce two novel quantitative footprint indicators to evaluate the territorial withdrawal of water in relation to its local water PBs. The water exceedance footprint measures the exceeded amount of water withdrawn in relation to local water PBs sensitive to the specific demand in a province or city. The surplus water footprint measures the amount of surplus water available within local water PBs that can be sustainably utilised to meet the demand of a province or city. The merits of using both metrics as a complementary tool to the conventional water footprint support the reconciliation of sustainable appropriation of water resources within biophysical boundaries. These novel indicators offer a new lens to explore how PB-exceeded and surplus water are appropriated, and allow comparisons across key commodities and geographical areas.
We use China as a case study as its sub-national level water availability is highly uneven, seasonal and vulnerable to climate change (Feng et al., 2019; Li et al., 2015; Piao et al., 2010). Within a nation, production in resource scarce regions can be redistributed to avoid the transgression of local PBs (Huang et al., 2020), while ensuring social equity and economic efficiency at the national level. A localised evaluation of the extent of transgression at a much greater spatial resolution is necessary. Northern China is highly water stressed (with only 18% of the nation’s freshwater resources) whereas the South, by contrast, is relatively water abundant, with most runoff wasted through flooding and some significant water quality issues (Guan et al., 2014; Liu and Yang, 2012). China has a per-capita water availability of 2100 m3/cap, only 28% of the global average (Cai et al., 2020). The North China Plain, a major food basket region and home to 200 million people, only has a per capita water availability of less than 150 m3/year (Liu et al., 2013). Outsourcing of increasing food, water and energy demand from major centers of consumption appears to exacerbate water stress elsewhere, for instance, the Jing-Jin-Ji area (Zhao et al., 2017; Zheng et al., 2019), the Greater Bay Area (Chen et al., 2019) and the Yangtze River Delta (Zhao et al., 2016). Continuing development of provinces and mega-cities may be hampered by water stress risks in their supplying hinterlands and overconsumption by a growing middle-class may further exacerbate their vulnerabilities (Liao et al., 2020; Qu et al., 2017; Zhang et al., 2020a).
The role of virtual water trade in redistributing scarce water resources within China is not always effective, in particular due to the consumption disparities between East China and West China, as well as a mismatch of arable land and water between arid North China and temperate South China (Feng et al., 2014; Guan and Hubacek, 2007; Zhao et al., 2015). Most interprovincial water footprint studies find that affluent eastern provinces and coastal cities, in addition to their significant local domestic water use, are typically net virtual water-importers from other, often water scarce northern and western provinces (Liu et al., 2020). Meanwhile, irrigation-intensive provinces in the drier North tend to export agricultural products to relatively wetter South regions where crop production is predominantly rainfed (Dalin et al., 2014). Internationally, China is a net virtual water importer for agricultural products (−25 km3) but net virtual water exporter if both agricultural and industrial products are considered (47 km3) (Hoekstra and Mekonnen, 2012; Wang and Zimmerman, 2016).
In this paper we demonstrate how novel PB-integrated water footprint indicators can be used to address ongoing challenges for water conservation policy in China. These quantitative footprint indicators link PBs at various scales to final consumption and quantify the magnitude and spatial extent required for water exceedance mitigation. Using the newly developed indicators we further explore how PB-informed virtual water trade can effectively redistribute resources within biophysical boundaries, therefore achieving absolute water sustainability.
Section snippets
Defining two novel water footprint indicators
We follow Li et al. (2019)’s exceedance concept to define our water extensions. Territorially, an over-withdrawal of water that exceeds the local water PB can be defined as Domestic Water Exceedance (DWE), i.e. water withdrawal subtracted by local water PB (see Graphical Abstract). DWE is measured in km3. For example, if the water withdrawal of the Paddy Rice sector in Jiangsu is 18.2 km3 and the local water PB is 9.3 km3, then the DWE of this sector is 8.9 km3. From a consumption perspective,
Provincial and city WEF and SWF in China
China’s domestic water exceedance in 2015 reach 101 km3 while the water exceedance footprint is 92 km3 (Fig. 1a). Foreign export accounts for 26% of the national DWE and foreign import accounts for 18% of the national total WEF. RWE amounts to 28 km3.
All provinces and cities compromise the water sustainability of other provinces or nations by significantly products and services causing local water exceedance (shaded in orange bars) (Fig. 1a). Of the 65 km3 WEEI, 77% (51 km3) are imported from
Advances in planetary boundary integrated footprint indicators
The global water PB delineates a ‘safe operating space’ for collective human modifications of the water cycle but the challenge is to translate the global water PB framework to local scales at which water management and governance occurs. Our paper directly addresses this gap by introducing two novel quantitative footprint indicators to contextualise the water PB framework at sub-national scale. Following Li et al. (2019)’s appraisal of global phosphorus exceedance footprint, this study
Conclusions
By comparing volumetric water footprints with water planetary boundaries at the local scale, we quantify the extent of PB transgression and the proportion of safe operating space that is appropriated by final demand for goods and services at the regional and inter-regional level. We argue that accounting for water exceedance or surplus is one tool that will help achieve China’s ambition of an Ecological Civilization while remaining within local water planetary boundaries. A revised virtual
Author contributions
M.L. implemented the model, designed by T.W., M.L. and M.H., M.L. performed calculations, analysed results and prepared the manuscript. M.L., T.W., M.H. and J.L. interpreted the results and wrote the paper. Y.W. compiled the MRIO table used in this study. Y.H. provided the provincial agricultural water withdrawal data and 2014 GTAP v10 MRIO table. Z.Z. provided the provincial level industrial, service and construction sector water withdrawal data.
Funding
This research was supported by Australian Research Council grant DP190102277. J.L. was supported by the National Natural Science Foundation of China (grant number 41625001; 51711520317). Y. W was supported by the Major Program of National Philosophy and Social Science Foundation of China (grant number 16ZDA051).
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
We thank Dr. Mengyu Li from University of Sydney for generating global water withdrawal data from the Global IELab.
References (108)
- et al.
Planetary boundaries revisited: a view through the ‘water lens’
Curr. Opin. Env. Sust.
(2013) - et al.
Direct and embodied energy-water-carbon nexus at an inter-regional scale
Appl. Energy
(2019) - et al.
National environmental limits and footprints based on the Planetary Boundaries framework: the case of Switzerland
Global Environ. Change
(2018) - et al.
Satisfying future water demands for agriculture
Agric. Water Manag.
(2010) - et al.
Safe and just operating spaces for regional social-ecological systems
Global Environ. Change
(2014) - et al.
Comment on “Explaining virtual water trade: a spatial-temporal analysis of the comparative advantage of land, labor and water in China,” published by Zhao et al. [Water Research (2019) 153: 304-314]
Water Res.
(2019) - et al.
Understanding of water resilience in the Anthropocene
J. Hydrol. X
(2019) - et al.
Towards a revised planetary boundary for consumptive freshwater use: role of environmental flow requirements
Curr. Opin. Env. Sust.
(2013) - et al.
The water planetary boundary: interrogation and revision
One Earth
(2020) - et al.
Water markets in the Murray-Darling basin
Agric. Water Manag.
(2014)
Assessment of regional trade and virtual water flows in China
Ecol. Econ.
A flexible framework for assessing the sustainability of alternative water supply options
Sci. Total Environ.
From Planetary Boundaries to national fair shares of the global safe operating space - how can the scales be bridged?
Global Environ. Chang. Hum. Policy Dimens.
The water footprint concept and water’s grand environmental challenges
One Earth
Operationalizing safe operating space for regional social-ecological systems
Sci. Total Environ.
Balancing food production within the planetary water boundary
J. Clean. Prod.
Interplay of trade and food system resilience: gains on supply diversity over time at the cost of trade independency
Glob. Food Secur.
Potentials and limitations of footprints for gauging environmental sustainability
Curr. Opin. Env. Sust.
Compiling and using input–output frameworks through collaborative virtual laboratories
Sci. Total Environ.
Towards meaningful consumption-based planetary boundary indicators: the phosphorus exceedance footprint
Global Environ. Change
Comparing water footprint and water scarcity footprint of energy demand in China’s six megacities
Appl. Energy
Water sustainability for China and beyond
Science
Water conservancy projects in China: achievements, challenges and way forward
Global Environ. Change
Can virtual water trade save water resources?
Water Res.
Environmental sustainability of water footprint in Mainland China
Geogr. Sustain.
Allocating planetary boundaries to large economies: distributional consequences of alternative perspectives on distributive fairness
Global Environ. Change
Spatially explicit assessment of water embodied in European trade: a product-level multi-regional input-output analysis
Global Environ. Change
Simulating the impact of new industries on the economy: the case of biorefining in Australia
Ecol. Econ.
Urban water management: can UN SDG 6 be met within the planetary boundaries?
Environ. Sci. Pol.
International inequality of environmental pressures: decomposition and comparative analysis
Ecol. Indicat.
Evaluating the vulnerability of physical and virtual water resource networks in China’s megacities
Resour. Conserv. Recycl.
Human domination of the global water cycle absent from depictions and perceptions
Nat. Geosci.
The GTAP data base: version 10
J. Global Econ. Anal.
Critical regions: a model-based estimation of world water resources sensitive to global changes
Aquat. Sci.
GDP Growth (Annual %)
Tension of agricultural land and water use in China’s trade: tele-connections, hidden drivers and potential solutions
Environ. Sci. Technol.
Quantifying the human impact on water resources: a critical review of the water footprint concept
Hydrol. Earth Syst. Sci.
China Custom Statistics Yearbook
Tracking sustainable development with a national barometer for South Africa using a downscaled “safe and just space” framework
Proc. Natl. Acad. Sci. U.S.A.
The global food-energy-water nexus
Rev. Geophys.
Water resources transfers through Chinese interprovincial and foreign food trade
Proc. Natl. Acad. Sci. Unit. States Am.
Increased food production and reduced water use through optimized crop distribution
Nat. Geosci.
Eurostat Manual of Supply, Use and Input-Output Tables
AQUASTAT Database
Virtual scarce water in China
Environ. Sci. Technol.
Domino effect of climate change over two millennia in ancient China’s Hexi Corridor
Nat. Sustain.
Regional size, regional specialization and the FLQ formula
Reg. Stud.
Performance Assessment Methods for the Implementation of the Most Stringent Water Resources Management System
Global water availability and requirements for future food production
J. Hydrometeorol.
Response to Comment on “Planetary boundaries: Guiding human development on a changing planet.”
Science
Cited by (56)
Spatio-temporal metabolic rifts in urban construction material circularity
2024, Resources, Conservation and RecyclingTracking the consumption-based CO<inf>2</inf> emissions of typical Chinese megacities in multiscale economies
2024, Journal of Cleaner ProductionEvolution of spatiotemporal pattern of virtual water in the Yangtze River economic belt
2024, Ecological IndicatorsDynamic simulation of the water-energy-food nexus (WEFN) based on a new nexus in arid zone: A case study in Ningxia, China
2023, Science of the Total Environment