PRODUCT WATER FOOTPRINTING: HOW TRANSFERABLE ARE THE CONCEPTS FROM CARBON FOOTPRINTING?

Transcription

1 PRODUCT WATER FOOTPRINTING: HOW TRANSFERABLE ARE THE CONCEPTS FROM CARBON FOOTPRINTING? B.G. Ridoutt 1, S.J. Eady 2, J. Sellahewa 3, L. Simons 4 and R. Bektash 5 1 CSIRO Materials Science and Engineering, Private Bag 10, Clayton, Victoria 3169, Australia 2 CSIRO Livestock Industries, Locked Bag 1, Armidale, NSW 2350, Australia 3 Food Science Australia, PO Box 52, North Ryde, NSW 2113, Australia 4 Food Science Australia, Private Bag 16, Werribee, Victoria 3030, Australia 5 Mars Asia Pacific, Petcare Place, Wodonga, Victoria 3690, Australia brad.ridoutt@csiro.au ABSTRACT Product carbon footprinting is becoming increasingly common in many parts of the world and is being supported through the development of standardised methodologies such as PAS2050. For many stakeholders the concept has broad appeal, being a simple and intuitive means of raising awareness of the life cycle GHG emissions associated with the production and consumption of products and services. This paper explores the transferability of the carbon footprint concept into water footprinting. It is based on carbon and water footprint case studies undertaken for Mars Australia involving Dolmio pasta sauce, Peanut M&M s, Whiskas cat food and Pedigree dog food. Suggestions are made about the direction of future development of the water footprint concept in order to make it a more useful driver for sustainable consumption and production. Keywords: water footprint, virtual water, carbon footprint, life cycle impact assessment 1. INTRODUCTION Freshwater has become a scarce and overexploited natural resource in many parts of the world, including parts of Australia (WRI, 2003). The social and environmental impacts are many and varied (Falkenmark, 2008) and there is frequent tension as water for human uses competes with water for the environment, so-called environmental flows (Smakhtin, 2008). From a global perspective, the seriousness of the problem is such that the availability of sufficient freshwater to meet future food production requirements has been questioned (Rockström, 2003). By 2050, as much as 59% of the world s population may face shortages of blue water (i.e. surface and groundwater) and 36% may face shortages of green water (i.e. soil water derived from rainfall and accessible for plant growth) and blue water combined (Rockström et al., 2009). In an effort to raise awareness of the impacts that the production and consumption of goods and services are having on freshwater resources, concepts such as virtual water (Allan, 1998) and water footprint (Chapagain and Hoekstra, 2004) have emerged. In Australia, the term water footprint has become part of the local vernacular, being added in 2008 to the Macquarie Dictionary. Water footprints for a range of products have also been reported in the popular media. For example, the Melbourne Age reported data from studies in the Netherlands indicating that it takes 140 litres of freshwater to produce a cup of coffee (125 ml), 200 litres for a glass of milk (200 ml), and 2000 litres for a cotton t-shirt (Gordon, 2007). The Australian reported that it takes somewhere between 50,000 and 100,000 litres of water to produce a kilogram of beef (Warren, 2008). While it is encouraging that freshwater scarcity and overexploitation have been recognised as important 1

2 issues, the danger is that the water footprint indicator has the potential to be misleading and confusing. CSIRO has been working with Mars Australia in the development and application of life-cycle based sustainability indicators for the agri-food sector. In the first stage of this research, product carbon and water footprints were developed for four case study products: Dolmio pasta sauce, Peanut M&M s, Whiskas cat food and Pedigree dog food. What distinguishes this work is its focus at the product brand level rather than the product category level, as well as the complexity and variability of the associated supply chains. Product carbon footprints were calculated following the second draft of PAS2050, the specification for the assessment of the life cycle greenhouse gas emissions of goods and services produced by the British Standards Institution (BSI, 2008). For product water footprinting, the approach of Chapagain et al. (2006) was adapted using many of the same principles found in PAS2050 in order to make it applicable at the product brand level. For example, the PAS2050 approach to defining the system boundary, functional unit and treatment of co-products and wastes was employed. Further details are described in Ridoutt et al. (2009). Based on the case study findings, we compare the carbon and water footprint concepts, and make suggestions about the direction of future development of water footprinting in order to make it a more useful driver for sustainable consumption and production (SCP). 2. COMPARING CARBON AND WATER FOOTPRINTING The broad appeal of product carbon footprinting stems from its simplicity (i.e. the emissions from all major greenhouse gases (GHGs) are normalised and expressed as a single figure in the units of carbon dioxide equivalents, CO 2 -e) and the intuitive link to global warning (Weidema et al., 2008). What this means is that the carbon footprints of different products and services can be meaningfully compared. In addition, the GHG emissions arising from different forms of consumption are additive, meaning that emissions can be calculated for a nation, a business, an individual or the life cycle of a specific product. Emissions associated with one form of consumption can also be offset by savings elsewhere. Another useful feature of carbon footprints is that they are comparable with the global warning potential (GWP) midpoint indicator used in life cycle assessment (LCA). As such, carbon footprinting can be regarded as a streamlined form of LCA, with commonality in approach to life cycle inventory and impact modelling. Unfortunately, water footprints do not share these same characteristics. While there are many examples of water footprints expressed as a single figure (some are listed above), these are not produced using a normalisation process. Carbon footprints are meaningful because the impacts of different greenhouse gases are normalised using commonly agreed characterisation factors, such as those published by the IPCC. In contrast, many published water footprints are the crude summation of more than one form of water consumption: blue, green and even dilution water (i.e. the volume of freshwater needed to assimilate emissions, Chapagain et al., 2006; Chapagain and Orr, 2009). As such, water footprints of different products are not comparable. For example, in comparing the total water footprint of 575 g Dolmio pasta sauce and 250 g Peanut M&M s, it is not evident which has the greater social and/or environmental impact from life cycle water consumption despite the pasta sauce having a total water footprint which is less than one fifth that of the confectionary product (Ridoutt et al., 2009). Different kinds of water consumption should not be simply added to produce a total water footprint because the opportunity cost and the impacts associated with each form of freshwater consumption differ. For example, in the case of Dolmio pasta sauce production, tomato growing consumes irrigation water. In the absence of production, this water would be fully available for some other productive purpose or could remain in the river system and contribute to the environmental flow. On the other hand, Peanut M&M s production requires cocoa derivatives, and the growing of cocoa beans consumes large quantities of green water. However, cocoa beans are typically grown as a tropical rainforest understory crop and it is questionable whether there would be any additional stream flow or groundwater recharge in the absence of production.

3 A further complicating factor is the regional nature of freshwater scarcity (Pfister et al., 2008; Chapagain and Orr, 2009). For carbon footprinting, the normalisation process for different greenhouse gases is simplified by the use of global characterisation factors, i.e. GHG emissions are regarded as making an equivalent contribution to global warming regardless of the location where they are produced (high altitude emissions arising from aviation being a notable exception). However, in the case of water footprinting, regional impact factors are necessary. Naturally, the impact of water consumed in a region of water abundance is in no way comparable to water use where scarcity exists. For example, in the case study of the Mars products, water consumed in crop production in the Murray Darling Basin of Australia is not equivalent in terms of impacts to water consumed in crop production in the tropical mountain regions of Sulawesi. Therefore, the water footprinting concept is in need of substantial further development in order to be used as a useful driver of sustainable consumption and production like carbon footprinting. It is not surprising that many agri-food companies and industry organisations have viewed the popularisation of water footprinting with some concern because of the potential for misinterpretation and confusion. This is despite these businesses and organisations having an awareness of the issues associated with freshwater scarcity and overexploitation and an expressed desire to reduce social and environmental impacts due to water consumption. 3. THE IMPACTS OF WATER APPROPRIATED INTO PRODUCT LIFE CYCLES As described above, the carbon footprinting methodology utilises characterisation factors for the various GHGs to enable normalisation and expression as a single figure in the units of carbon dioxide equivalents. In order to progress toward an analogous water footprint methodology, where the impacts of various forms of water consumption in various locations are normalised using appropriate characterisation factors, it is first necessary to identify the important impact category or categories that water footprinting is seeking to address. This endeavour has much in common with the UNEP/SETAC Life Cycle Initiative project which is developing a framework for assessing freshwater use in LCA (Koehler, 2008; Koehler et al., 2008). As already mentioned, a feature of carbon footprinting is its compatibility with LCA and it is desirable that the same occurs for water footprinting. In this regard, a point of tension exists. Because of the many and varied impacts of freshwater consumption (and pollution), LCA is likely to involve numerous impact categories spanning resource use, human health and ecosystem quality (Pfister et al., 2008). However, the broad appeal of water footprinting will likely be increased if the scope is limited to a single midpoint assessment. Following on from Ridoutt (2008) we recognise the following main impacts of water appropriated into agri-food product life cycles: 3.1 Social impacts of green water use Agri-food product life cycles appropriate green water through land occupation and there are three major social impacts. Firstly, occupation of the land limits the availability of the land and thereby access to the green water for other social purposes. For example, if land in Australia is being used to grow pulpwood for export, that same land and its associated green water is not available for other kinds of agricultural enterprise. Secondly, land use influences the partitioning between green and blue water and thereby the availability of blue water for other social purposes. Of particular concern in the Australian context is the transformation of pasture into industrial forestry, using deep rooted tree species which, in certain circumstances, may increase evapotranspiration and reduce stream flow (Benyon et al., 2007). Thirdly, land use change has the potential to alter rates of runoff and thereby increase or ameliorate risks of flooding. 3.2 Social impacts of renewable blue water use Blue water is surface or groundwater and it is mainly appropriated into agri-food product life cycles as irrigation water in farming and process water in factories. However, as noted by Rijsberman (2006, p.10), people who lack safe water for drinking and adequate water for sanitation are generally, not affected by water scarcity in the physical sense, but lack of access because the

4 water service delivery is poor, or because they do not have access to sufficient financial resources to avail themselves of the services, i.e. they are poor. As such blue water appropriated into agrifood product lifecycles is generally not the cause of domestic water shortages, poor sanitation or the resultant human health effects. In other ways, industrial users regularly compete for access to the same local freshwater resources. However, the socio-economic implications of competition between industries for natural resources are generally not within the scope of LCA. 3.3 Social impacts of non-renewable blue water use Where agri-food product life cycles appropriate non-renewable blue water from fossil groundwater resources, this limits the availability of these resources for future generations. 3.4 Environmental impacts of green water use As mentioned above, agri-food product life cycles appropriate green water through land occupation. With respect to environmental impacts, there are two major impact pathways. Firstly, as described above, land transformation and occupation influence the partitioning between green and blue water and thereby the availability of blue water for environmental flows. Secondly, additional green water for food production can be accessed by conversion of natural ecosystems into agricultural land. In this case, the impact is loss of natural ecosystems and habitat. 3.5 Environmental impacts of renewable blue water use Water for irrigation and industrial use competes with water for the environment and can lead to insufficient environmental flows with impacts on aquatic biodiversity as well as riparian, floodplain and estuarine ecosystems. Where surface water is used for irrigation, this will directly reduce stream flows. Other potential impacts include raising the water table, which in turn can lead to salinity and water logging. 3.6 Environmental impacts of non-renewable blue water use Where non-renewable groundwater resources are isolated from freshwater ecosystems their use does not affect ecosystem health. Where these groundwater systems support natural springs (e.g. The Great Artesian Basin) depletion can cause these to dry up resulting in damage to local (and sometimes unique) ecosystems and loss of biodiversity. 4. PROPOSED DIRECTION OF WATER FOOTPRINT METHOD DEVELOPMENT Based on the preceding discussion, we propose that the main concern relating to water consumption in agri-food product life cycles is the potential to damage freshwater ecosystem health through reduced environmental flows. The main impact pathways are the direct abstraction of renewable blue water resources (i.e. those that are hydrologically connected to freshwater ecosystems) as well as the change in blue water availability associated with land use. In regards to the latter, most agricultural systems intercept less precipitation than the natural ecosystems they replace (Scanlon et al., 2007). Indeed, simulations using the LPJmL dynamic global vegetation and water balance model suggest that globally, river discharges have increased by 6.6% as a result of transformation of natural ecosystems to crop and grazing land (Rost et al., 2008). An alternative approach to categorising land use effects on stream flow has been offered by Milà i Canals et al. (2009) involving a distinction between sealed and unsealed land use types and assumptions about the value of runoff from heavy rainfall to ecosystem health. Once an inventory is made of the volume of blue water consumed in each hydrologically-defined region (i.e. watershed or basin), characterisation factors can be applied which reflect the local water stress, as demonstrated by Pfister et al. (2008) in relation to a variety of vegetables.

5 A second concern relating to water consumption in agri-food product life cycles is depletion of nonrenewable (i.e. fossil) groundwater resources, which in the context of LCA is another form of abiotic resource depletion. This proposed water footprinting schema represents a substantial departure from existing water footprinting approaches. To begin with, what is being proposed now has a clearly defined goal (protection of freshwater ecosystems and avoidance of fossil groundwater depletion) and impact pathways. As a result, the potential exists to work toward agreed characterisation factors for different kinds of water appropriated in different locations, of the kind that is necessary to achieve normalised water footprint values which are comparable from one product to another. Another major point of departure from existing water footprint approaches is the lack of explicit accounting for green water consumption. It is our view that the consumption of green water is probably best considered in the context of the land use impact category due to the inseparability of green water and land. After all, green water is only one of the many resources acquired through land occupation: access to solar radiation, wind and soil are others. 4.1 Drivers for SCP created by the proposed approach to water footprinting The revised approach to water footprinting described above will create a range of positive incentives to reduce the environmental impacts of freshwater consumption. Water footprints can be reduced through: Reducing the sourcing of agricultural ingredients from locations with high environmental water stress which depend on irrigation for crop production; Reducing the sourcing of agricultural ingredients from locations/operations depending on large quantities of irrigation water per unit of production; Encouraging investments in farming systems which increase the efficiency of irrigation water use and decrease runoff and leaching of agri-chemicals; Encouraging investments in industry to improve water use efficiency, water reuse and recycling, and wastewater reduction and treatment; Influencing the location of new factories away from locations where renewable freshwater resources are scarce; and Shifting production away from consumption of non-renewable blue water resources. That said, this approach to water footprinting will not address other concerns, including: avoiding loss of natural ecosystems through agricultural expansion, increasing water productivity (i.e. crop per drop) in rain fed agricultural systems, maximising calorific or nutritive value per unit of water consumed, multistakeholder engagement with local water management agencies regarding sustainable use of local water supplies, development of water infrastructure for local communities, water efficiency in the domestic sector, land management to avoid flooding and flood damages, and impacts on the marine environment. 5. CONCLUSION This paper has identified that the major dissimilarity between product carbon and water footprinting is that the latter does not currently use characterisation factors to arrive at a normalised value which is comparable from one product to another. Due to the similarity in name between carbon and water footprinting, we argue that water footprinting should have a similar conceptual foundation to carbon footprinting (which is already in widespread use). This will avoid stakeholder confusion and maximise the potential of water footprinting as a driver for sustainable consumption and production. Current approaches to water footprinting need to be revised because a simple summation of different forms of water consumption sourced from different locations is potentially misleading, is not comparable from one product or service to another, and does not represent a clear relationship to environmental or social impact. At present, it is not clear what good would result from choosing a product or production system on the basis of it having a lower water

6 footprint. Indeed, a product with a lower water footprint could be more damaging to the environment than one with a higher water footprint depending upon where the water is sourced. This paper has articulated the major impacts of water appropriated into product life cycles and suggested a direction of future water footprint method development by focussing on potential to damage freshwater ecosystem health through reduced environmental flows. A priority among water footprint practitioners is to form agreement on the impact category or categories that are relevant to freshwater consumption and from this develop common characterisation models and factors. Insofar as possible, these should also be consistent with developments in life cycle impact assessment for freshwater consumption. 6. REFERENCES Allan, J.A., Virtual water: A strategic resource: Global solutions to regional deficits. Groundwater 36(4): Benyon, R., England, J., Eastham, J., Polglase, P. and White, D Tree Water Use in Forestry Compared to Other Dry-Land Agricultural Crops in the Victorian Context: Report prepared for the Department of Primary Industries Victoria. Ensis Technical Report no p. BSI (British Standards Institution), PAS2050:2008 (draft). Specification for the Assessment of the Life Cycle Greenhouse Gas Emissions of Goods and Services. British Standards Institution, UK. Chapagain, A.K. and Hoekstra, A.Y., Water Footprint of Nations, Value of Water Research Report Series No.16. UNESCO-IHE, Delft, The Netherlands. Chapagain, A.K., Hoekstra, A.Y., Savenije, H.H.G. and Gautam, R., The water footprint of cotton consumption: An assessment of the impact of worldwide consumption of cotton products on the water resources in the cotton producing countries. Ecological Economics 60(1): Chapagain, A.K. and Orr, S An improved water footprint methodology linking global consumption to local water resources: A case study of Spanish tomatoes. Journal of Environmental Management 90: Falkenmark, M., Water and sustainability: A reappraisal. Environment 50(2): Gordon, J Australian households world s worst at water use. The Age (Melbourne), Monday May 21: 3. Koehler, A Water use in LCA: Managing the planet s freshwater resources. International Journal of Life Cycle Assessment 13: Koehler, A., Aoustin, E., Bayart, J-B., Bulle, C., Margni, M., Pfister, S. and Vince, F A framework for assessing (fresh) water use within LCA: First results from the related project under the UNEP/SETAC Life Cycle Initiative. SETAC North America 29 th Annual Meeting, Tampa, FL, USA, 17 November Milà i Canals, L., Chenoweth, J., Chapagain, A., Orr, S., Antón, A. and Clift, R Assessing freshwater use impacts in LCA: Part 1 Inventory modelling and characterisation factors for the main impact pathways. International Journal of Life Cycle Assessment 14: Pfister, S., Stoessel, F., Juraske, R., Koehler, A. and Hellweg, S Regionalised LCIA of vegetable and fruit production: Quantifying the environmental impacts of freshwater use. Proceedings 6 th International Conference on Life Cycle Assessment in the Agri-Food Sector, Zurich, Switzerland, November 2008, pp Ridoutt, B.G Identifying standard measurement methodologies. Corporate Water Footprint Summit, London, December Ridoutt, B.G., Eady, S.J., Sellahewa, J., Simons, L. and Bektash, R Water footprinting at the product brand level: case study and future challenges. Journal of Cleaner Production (submitted). Rijsberman, F.R Water scarcity: Fact or fiction? Agricultural Water Management 80: 5-22.

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