Life cycle assessments measure water's impact on Earth's ecosystems for first time
The damages to ecological systems from overconsumption of water are illustrated in this world map (yellow represents low impacts, navy high impacts).
Figure 3, PFISTER ET AL.
LCA's finally measure water consumption
Environ. Sci. Technol., Article ASAP
Publication Date (Web): April 22, 2009
Copyright © 2009 American Chemical Society
Despite water’s significance, modeling how freshwater consumption for drinking, industrial manufacturing, and agriculture has affected ecosystems, human health, and the depletion of nonrenewable freshwater resources has been overlooked. In a new ES&T study (DOI 10.1021/es802423e), researchers take the traditional life-cycle assessment (LCA) approach one huge step beyond current practices with a model that incorporates water consumption.LCA models were created to address problems in industrialized nations, and most of these countries don’t experience human-health risks due to water scarcity, the authors note. Recently, researchers have started to use LCA models to manage diminishing resources in developing countries. To incorporate water consumption into the LCA process, Stephan Pfister, Annette Koehler, and Stefanie Hellweg at the Swiss Federal Institute of Technology Zurich’s (ETH Zurich’s) Institute of Environmental Engineering started from scratch: they created units of measure for water consumption that are compatible with the many values for energy and resource use that appear in an internationally recognized LCA method. “For water use, this hadn’t been done, ever,” says Hellweg, who is a professor of ecological systems design at ETH Zurich.
For example, the team interpreted a well-known value established by the World Health Organization in LCA models and applied it to water use. The disability-adjusted life year is a value that expresses the number of years a person's life will be shortened as a result of disease or premature death. The team also adapted an indicator applied to address ecosystem impacts and known as PDF (potentially disappeared fraction of species) to express how water impacts species.LCAs routinely rely on aggregated data to represent large areas. But the ecological impacts of water use depend on regional factors, such as freshwater availability, water infrastructure, rainfall, and consumption patterns at a specific location. The team used a geographic information system to gather regional data and divided large rivers, such as the Nile and the Mississippi, into subcatchments. “The watershed level is more appropriate for the assessment, because hydrological processes are connected within watersheds,” Pfister says.
In the paper, Pfister and colleagues demonstrate their model with a case study of a process that is water-intensive worldwide: cotton production. They began with data from the “virtual water” database developed by researchers in The Netherlands. A relatively new idea, virtual water describes the amount of water that evaporates during agricultural use. Specifically, the database is an inventory of the water consumed for agricultural use for many crops in most countries.The team found that the impacts from water consumption in the cotton industry vary according to country: Egypt’s water supply experiences the highest level of damage (77%) from cotton production, whereas Brazil experiences the lowest level of damage (0%), followed by the U.S. (4%).
The model’s focus on the resulting damage to ecosystems and human health is somewhat controversial among LCA practitioners in general, some modelers told ES&T. Many U.S. researchers tend to stick to LCAs that create resource-use inventories but that don’t measure ecological or human-health impacts, notes Christopher Weber of Carnegie Mellon University. Referring to the new ES&T study, Weber says: “There is a great deal of uncertainty in their inventory, and there is still disagreement over many of the definitions they use.” Modelers in the U.S. also shy away from incorporating water into LCAs because there is a shortage of water data in this country, explains Chris Hendrickson, also of Carnegie Mellon. More data are available for the EU, and for areas with water scarcity, such as in Israel, Hendrickson says.
Nonetheless, the study demonstrates a huge range of work, Weber says. “I absolutely think that [the] method they are using is a good one,” he says. “It’s good to take the next step and to turn water use into something that can be used to compare it to something else, such as toxic releases or CO2.”Pfister says that within the LCA community, work has been done to clearly define the terms related to water use. “Our method directly uses those definitions,” he adds.
Despite the uncertainties inherent in all LCAs, the researchers are confident that this approach, as well as the assumptions they make in this study, will compare favorably with other LCA methods. The group members say that they hope their work will be used by businesses and governments that are searching for ways to protect diminishing water resources. Some nonbinding declarations in the EU suggest that consumer goods show LCA information on product labels, and many companies are beginning to conduct LCAs, Pfister says.Determining water use “has really become popular in the last year,” Hellweg says. “But companies are not really looking at what happens afterwards, and they are all looking at water use in an aggrandized area,” she adds. “I really hope that businesses take this one more step and incorporate the differences of water use in Egypt compared with water use in a wet country such as Switzerland,” Hellweg says.
It is good to finally see life cycle assessments being done for water use. The impact of water use on our ecosystems should be of chief concern in every area of the world as water is the one resource we cannot live without.
More water is wasted(and polluted) in industry, yet they are not accountable for the water they use. And even though these assessments are not ironclad based on changing factors over time, they at least give a good idea of what is being used, wasted, and how best to conserve water in different regions of the world experiencing different effects regarding that usage due to population, population growth, deforestation, agriculture, and now chiefly, climate change which is precipitating drought and melting glaciers more rapidly which absolutely effects the life cycle of water and all that depend on it.
It is time to take our use of water much more seriously. It is the lynchpin of our survival on this plaent and if we are to have any success at all in preserving our planet for ourselves and those to come, how we manage water is essential to that success and preservation.