Photo: Many Hands Organic Farm (mhof.net)Un résumé traduit d'un article intéressant dans le Scientific American:
Certains environnementalistes veulent que les produits portent une étiquette affichant leur empreinte aquatique, afin que les consommateurs soient sensibilisés aux besoins en eau d'une telle production ou d'un tel produit comparé à un autre. Par exemple, la tasse de café demande beaucoup plus qu'une tasse d'eau de votre robinet si vous compter l'eau nécessaire pour faire pousser ce café, la préparation des fèves pour le marché et le transport.
L'empreinte carbone est un concept compris, sinon connue, par la plupart des gens, et il serait peut-être temps de pouvoir évaluer l'usage que l'on fait de notre ressource la plus précieuse. Mais faire consensus n'est pas facile. Selon certains, la nourriture et l'énergie consomment presque 90% de l'eau douce de la planète.
Et ce n'est pas suffisant de savoir combien de litres sont nécessaires pour tel produit, il est aussi important de connaître l'endroit où la plante se situe. Le maïs qui pousse dans un état où la pluie suffit à produire une récolte a un moindre impact sur les autres besoins en eau de la région que le maïs qui doit être irrigué pour produire, privant ainsi la population locale et les écosystèmes indigènes de l'eau qu'ils ont besoin pour survivre.
Les balises actuelles de l'empreinte aquatique ne tiennent pas compte de ces différences. Les impacts qu'ont les produits sur l'environnement ne sont pas inclus dans les méthodes connues de mesure des demandes en eau. Mais plusieurs pensent que d'étiqueter la quantité en litres nécessaires pour produire une nourriture serait déjà un bon commencement pour informer le consommateur et l'aider dans son choix à l'épicerie.
J'ose ajouter à cet article qu'il serait important d'inclure le barème suivant: la quantité d'eaux usées ou polluées générées par le cycle de vie d'un produit et l'impact sur l'écosystème aquatique local qu'ont ces eaux usées. Par exemple, comparons un jambon venant d'un porc élevée sur gestion liquide dans une méga-porcherie, et un jambon venant d'un porc élevé autrement. Le porc industriel vient d'un cochon dont les excréments sont lavés avec de l'eau, dont la bâtisse est rafraîchie l'été par des jets d'eau, et les excréments mêlés à l'eau sont ensuite entreposés dans une fosse pour être épandus plus tard sur des champs bien draînés, aux bandes riveraines filtrantes presqu'absentes (au Québec en tout cas!), sur un sol dénudé parce que si je me fie aux épandages autour de chez moi, l'épandage se fait surtout à la fin d'automne, quand les récoltes sont entrées, quand le sol est dénudé, et de préférence la veille d'une pluie abondante annoncée par Environnement Canada. Inutile d'ajouter que l'effet sur la rivière avoisinante est désastreux!
Par contre, un jambon qui vient d'un porc élevé autrement peut aller dehors pour se rafraîchir lors des grandes chaleurs, composte lui-même ses excréments avec sa litière faite de paille ou de copeaux qui seront épandus dans des champs entourés de bandes riveraines assez larges pour abriter des oiseaux et des insectes. Gagez-vous qu'on peut se baigner sans crainte dans le ruisseau à côté d'une telle ferme?
Photo: mhof.net"Awash in Awareness: Knowing a Product's "Water Footprint" May Help Consumers Conserve H2O
Environmentalists think food products should be labeled according to how much water is used to produce them. If you think your morning cup of joe only has 12 ounces (35 centiliters) of water in it, you're sorely mistaken—it has closer to 40 gallons (150 liters). Conservation scientists say it's time consumers become aware of the quantity and source of water that goes into growing, manufacturing and shipping food.
Concerns over greenhouse gas emissions have vaulted the term "carbon footprint" into mainstream vernacular. Now, by promoting the concept of a "water footprint" with the goal of including it on product labels, researchers are hoping to draw similar attention to how drastically we're draining our most precious resource. As the use of a footprint to gauge water use gains popularity, however, researchers are struggling to reach a consensus on how best to measure that footprint so the public understands its full impact.
As currently defined, a product's water footprint is an inventory of the total amount of water that goes into its manufacture. For that cup of coffee, for instance, most of the 40 gallons flow either into watering coffee plants or cooling the roasters during processing.
"Most people have no idea how much fresh water they're consuming," says Brad Ridoutt, a water conservation specialist from Australia's Commonwealth Scientific and Industrial Research Organization. According to Ridoutt, food and energy production account for nearly 90 percent of the world's fresh water consumption.
The water footprint is designed to help consumers and businesses understand just how much water is required to make products like a cotton T-shirt or a can of corn. But according to Ridoutt, just counting gallons is not enough, because consumers also value where that water came from. Corn grown in Minnesota, for example, depends on rainwater, which is abundant and not otherwise used by people. But in Arizona corn crops depend on scarce reservoir water also used for drinking, hygiene and other consumer needs. The current definition of the water footprint doesn't address these discrepancies.
In a study published in the February issue of the journal Global Environmental Change, Ridoutt proposed a strategy that takes the original location of the water into account in evaluating the environmental impact of its use in product manufacturing.
To illustrate his ideas, Ridoutt chose two common household food items: an 18-ounce (53-centiliter) jar of Dolmio pasta sauce and a small bag of peanut M&M's. For the pasta sauce, the volume of water needed to grow the tomatoes, sugar, garlic and onions added up to 52 gallons (197 liters). For the M&M's, the total volume going into all the ingredients was a whopping 300 gallons (1,135 liters).
Comparing these conventional water footprint values would lead one to think the bag of M&M's takes a far worse toll on freshwater resources. But that isn't the complete picture, Ridoutt says.
Because tomato plants are typically grown in hot, dry climates, they are watered using irrigation systems that draw from the same locations as human drinking water. On the other hand, the cocoa and peanuts in M&M's are grown in more temperate regions, where the crops absorb rainwater directly from the ground. Taking location into account, Ridoutt says, drastically changes how you think about the water going into your food. According to his calculations, the pasta sauce is about 10 times more likely than the M&M's to contribute to water scarcity.
Ridoutt is not the only one trying to redefine the water footprint. Conservationists around the world are trying to figure out how to best include environmental impact in the footprints so they can be incorporated into food labels. The International Organization for Standardization now has a project underway to tackle this problem using methods similar to Ridoutt's.
Although many researchers support Ridoutt's work, others say we don't yet know enough about global water cycles to accurately measure environmental impact. Organizations such as the Water Footprint Network and the World Wildlife Fund (WWF) still believe that simply reporting the total volume of water is currently the best and clearest way to communicate a water footprint.
"The paper Brad has written has quite a high value, but there is a long way to go," says the WWF's Ashok Chapagain, who has been studying water footprint methods for over five years. Without an agreed-on standard, reporting water footprints simply as volumes is the easiest for consumers and businesses to understand, he says.
Ridoutt, on the other hand, believes his method will turn out to be more useful for consumers, and he hopes that when footprints are applied to food products in the future, they won't be just a sum of all the water they have used. "If you want to communicate something to the public in a simple way," he says, "you have to express it in a way that gives the [environmental] impact."
This article is provided by Scienceline, a project of New York University's Science, Health and Environmental Reporting Program."
Excerpts from article written by Alyson Kenward published in Scientific American here: http://www.scientificamerican.com/article.cfm?id=water-footprint
Like a reader commented rightly so, this method of measuring the amount of water used through a process or a product's manufacturing or growth does not take into account the pollution generated and the effect the polluted water has on surrounding watercourses. Take for example a mass-produced ham VS an organic ham. If I choose to eat a ham that comes from the 5,800 pig farm upriver, the way they deal with the waste is by washing it down and storing it in concrete pits to be able to later spread it on well-drained fields, on clay-based soil, on farmland all along a river with barely any green protection strips along the ditches, and the spreading done preferably before an abundant fore-casted rainfall, usually in late autumn when no crops are left in the field. The water quality impact of this ham is devastating!
If on the other hand I choose to buy a more expensive but tastier organic ham, this would come from a farm further inland away from a main river, coming from a pig raised on straw or wood chips, that goes outside in the summer to cool down instead of being sprayed with water, whose composted manure is spread dry over fields of an organic farm that leaves wider green buffer zones along its local streams and ditches to give home to a diversity of birds and insects. Bet you the streams along this farm is cleaner and even swimmable! I'm convinced the organic ham has a much smaller water footprint than the CAFO (concentrated animal feeding operation) one!
Photo: mhof.net
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