water
Editorial
Water Footprint and Life Cycle Assessment: The
Complementary Strengths of Analyzing Global Freshwater
Appropriation and Resulting Local Impacts
Winnie Gerbens-Leenes 1,* , Markus Berger 2and John Anthony Allan 3
Citation: Gerbens-Leenes, W.; Berger,
M.; Allan, J.A. Water Footprint and
Life Cycle Assessment: The
Complementary Strengths of
Analyzing Global Freshwater
Appropriation and Resulting Local
Impacts. Water 2021,13, 803.
https://doi.org/10.3390/w13060803
Received: 19 February 2021
Accepted: 9 March 2021
Published: 15 March 2021
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1Integrated Research on Energy, Environment and Society, Faculty of Science and Engineering,
University of Groningen, 9747 AG Groningen, The Netherlands
2
3King’s College London, SOAS University of London, London WC1H 0XG, UK; [email protected]
*Correspondence: p.w[email protected]
1. Introduction
Considering that 4 billion people are living in water-stressed regions and that global
water consumption is predicted to increase continuously [
1
], the analysis of water con-
sumption and pollution along supply chains and resulting water scarcity issues is of great
relevance. Since 2002, researchers from the Water Footprint (WF) community have been
analyzing the global freshwater appropriation of products, companies and nations differ-
entiating the consumption of green water (precipitation), blue water (ground and surface
water) as well as gray water (theoretical amount of freshwater needed to dilute polluted
water to accepted water quality standards) [
2
]. A few years later, water was an emerging
field of research in Life Cycle Assessment (LCA), which aimed at assessing local impacts of
water consumption and pollution in combination with those of greenhouse gas emissions,
land use changes, etc. [
3
,
4
]. Since the beginning of these research efforts there has been
a persistent debate on the orientation of the Water Footprint. In this editorial we want
to shed light on the background of the methodological dispute and highlight points of
disagreement but also similarities and common challenges. Further, we want to call for joint
efforts from the WF and LCA communities to tackle the increasing global water challenges
together. The analysis will widen the discussion by highlighting the questions that the two
approaches could be trying to answer [5].
2. The Developments of Water Footprinting in the WF and LCA Communities
Studies on water use and scarcity in relation to consumption and trade were initiated
by Tony Allan who first proposed the concept of embedded water, and later the more
popular one of virtual water [
6
]. Allan worked on the Middle East from the mid-1960s and
noted that the region had run out of water to meet its food needs by the 1970s. He also
asked the question of why had the intuitively rational and much discussed outcome—water
wars—not occurred? The answer was that this existential and potentially very destabilizing
problem was solved by importing water-intense crops. One of the most important features
of this solution was that the food commodities being imported were underpriced. The
exporters, such as the United States for example, were not including the costs of their water
inputs or the costs of the negative impacts on biodiversity and emissions associated with
their production. Decades later they still don’t. In 2002, Hoekstra [
7
] introduced the WF
concept at an international expert meeting on virtual water trade. He showed that the
WF approach is multi-dimensional. It indicated water consumption volumes and water
pollution by type of pollution specified per location and in time [
8
]. The sustainability of
water use can be assessed by comparing WFs with available water, taking environmental
flow requirements into account [
9
]. Using the WF indicator, Mekonnen and Hoekstra [
10
]
Water 2021,13, 803. https://doi.org/10.3390/w13060803 https://www.mdpi.com/journal/water
Water 2021,13, 803 2 of 6
quantified the gap between WFs and water availability and showed that a large part of the
global population had faced water scarcity for some decades.
With an increasing application of LCA on biofuels, food and renewable raw materials,
water resources have been acknowledged to be a relevant aspect that should be considered
in LCA. LCA focuses on assessing environmental impacts (e.g., loss of biodiversity) result-
ing from environmental interferences along products’ life cycles (e.g., land use change).
As impacts of water resource consumption differ depending on regional scarcity and
socio-economic conditions, authors from the LCA community argued for impact-based
assessments [
11
]. As summarized by researchers from the “Water as a Global Resource”
initiative [
12
] some of those impact assessment methods estimate the local consequences of
water consumption based on freshwater scarcity [
13
–
15
]. Other methods assess the effects
of water consumption on human health and well-being (due to malnutrition [
13
,
16
,
17
] or
infectious diseases [
16
,
18
]), ecosystems (terrestrial [
13
,
19
,
20
], aquatic [
21
,
22
], coastal [
23
],
wetlands [
24
], urban [
25
]), and freshwater resources [
13
,
26
,
27
]. The methodological en-
hancements and relevance of global freshwater use has led to the development of an
international WF standard (ISO 14046) which specifies principles, requirements and guide-
lines related to WF analyses of products, processes and organizations [28].
3. The Scientific Dispute between Two Research Communities
As mentioned above, there has been a persistent debate on methodology between
the WF and the LCA communities—mainly on the question whether the water footprint
should be a volumetric or an impact-based indicator. WF scientists put the focus on water
management and the volumetric analysis of water consumption and pollution, arguing
that water is not only a local resource, but also a global one because water is virtually
‘traded’ worldwide via goods and products [
2
]. An analysis of local consequences of
water use is considered an optional step. In contrast, the LCA community has argued that
1 m3
of blue water consumption in a water scarce region is not the same as 1 m
3
of green
water consumption in a water abundant region [
29
]. It claimed that volumetric footprints
“have the potential to misinform” [
30
], and it has highlighted the necessity of an impact
assessment step, which is also prescribed in the ISO standard on water footprinting [
28
].
Vice versa, the WF community has criticized the impact assessment methods developed
in the LCA scene as a “meaningless construct” [
31
] or “contraproductive in reaching the
Sustainable Development Goal (SDG) target 6.4” [
32
], especially if impact factors in LCA
assessments were deployed. Methods which try to model cause–effect chains of water
consumption leading to loss of biodiversity (e.g., [
13
]) or human health (e.g., [
17
]) have
been criticized as “complete madness” [31].
This fundamental disagreement has led to a situation in which scientists from both
communities have hardly talked to each other but about each other—in endless “reply to”
paper series such as Hoekstra et al. (2009) [
33
] replying to Pfister and Hellweg (2009) [
34
]
commenting on Gerbens-Leenes et al. (2009) [
35
], or Hoekstra and Mekonnen (2012b) [
36
]
replying to Ridoutt and Huang (2012) [
30
] criticizing Hoekstra and Mekonnen (2012a) [
37
],
etc. Considering increasing global water challenges, we feel that less energy should be
wasted in such methodological battles and that the WF and LCA communities should enter
more fruitful modes of discourse and cooperation. The conflict between the communities
has proven to be very unhelpful. It does not for example help to answer a second question:
Why is the international ‘trade’ in virtual water and its negative impacts on water resources,
soil health, biodiversity and emissions still invisible to legislators and society? And why
has this condition been firmly backgrounded [5].
4. Points of Agreement, Disagreement and Common Challenges Ahead
As a starting point for a constructive scientific exchange, we list the main points of
agreement, as well as points on which we disagree on which both communities should try
to find consensus. We also identify challenges faced by both communities if their analyses
are to be policy relevant.
Water 2021,13, 803 3 of 6
4.1. Points of Agreement
•
First and foremost, WF and LCA share the same goal: the achievement of sustainable
water consumption along the value chains of products and services.
•
Both WF and LCA start with volumetric accounting and add a subsequent impact
assessment step—the difference is the focus on volumes (WF) or impacts (LCA), which
doesn’t mean that the other part is meaningless.
•
Methods developed in the “water footprint sustainability assessment” step (WF) can
be used in the impact assessment phase of LCA and vice versa.
•
Both communities highlight the relevance of spatial and temporal information and
aim at increasing their resolution.
•
Water pollution data generated by LCA can be applied for grey WF analysis. For
example, the study of Gerbens-Leenes et al. [
38
] applied LCA data on water pollution
for the assessment of the blue and grey water footprint of steel, cement and glass.
4.2. Points of Disagreement:
•
Differences between the LCA and WF communities are evident in their definition
of terminology. For example, the term “water footprint” is defined as “volume of
freshwater used to produce goods and services” in the WF community [
9
] but as
“metric(s) that quantify the potential environmental impacts related to water” in the
LCA community [
28
]. This difference reflects the conflictive opinions on whether the
water footprint should be a volumetric or impact-oriented indicator.
•
In LCA, impact assessment is a central step in which the volumes of local water
consumption are multiplied by a corresponding characterization factor, which denotes
the local consequences of water consumption. In WF, the volumes are the central
results and impacts can be analyzed in a subsequent step.
•
Water use efficiency is not the focus of LCA [
39
,
40
] and it is assumed that water can
be used without causing environmental harm in water abundant basins. In contrast,
the WF approach considers that water efficiency is always important. This global
perspective means that water resources should not be wasted. Water abundant basins
are important as they enable the global food system to be impressively resilient but at
the same time very dangerously unsustainable both economically and ecologically.
•
Green water consumption is an essential part of the WF concept and often dominates
a WF study. It is considered relevant as green water should be used as efficiently
as possible and as green water resources used by agricultural systems are lost for
local ecosystems. In LCA, green water consumption of agricultural systems is usually
considered as a consequence of land-use change and impacts on biodiversity of
this land-use change are already covered in the respective impact categories. Thus,
green water is usually ignored as no additional impacts are seen to result from the
evapotranspiration of rainwater. If at all, the change of evapotranspiration between the
agricultural system and the natural vegetation, i.e., the net green water footprint [
41
],
is considered.
•
Water pollution in WF studies is assessed as the amount of water needed to dilute
polluted water to accepted water quality standards, while LCA measures impacts
resulting from pollutants in separate impact categories, such as eutrophication, eco-
toxicity, etc.
•Focusing only on water (WF) or including water in a broader scope (LCA).
4.3. Common Challenges
There are six important scoping and conceptual challenges that face those proposing
to carry out water resources studies deploying WF and LCA approaches. These are how to
achieve the following:
•
Include basin specific environmental flow requirements in the water scarcity assess-
ments.
•Include all pollutants in agricultural WF studies, and not only focus on nitrogen.
Water 2021,13, 803 4 of 6
•Assess water availability issues related to pollution.
•
Access data for determining water use of products and services as well as (commercial)
databases.
•
Handle trade-offs between blue, green and gray water footprints but also between the
water footprint and other environmental indictors (carbon footprint, land use, etc.) as
well as other sustainability dimensions (social- and economic aspects).
•
And finally: How can both communities take the next step from academic studies to
decision relevance that supports sustainable water resource policies and practice?
5. Call for Action
In this special issue, researchers and stakeholders representing the WF and LCA com-
munities are invited to submit methodological work, reviews as well as case studies to illus-
trate the complementary strengths of both approaches. We especially encourage researchers
from both communities to cooperate and discuss the points of disagreement and challenges
mentioned above in order to tackle the increasing global water challenge together.
Author Contributions:
All authors developed the idea for this paper, accomplished the analysis and
wrote the manuscript together. All authors have read and agreed to the published version of the
manuscript.
Funding: This research received no external funding.
Institutional Review Board Statement: Not applicable.
Informed Consent Statement: Not applicable.
Data Availability Statement: Data sharing not applicable.
Conflicts of Interest: The authors declare no conflict of interest.
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