المنتدى العالمي المعني بالأمن الغذائي والتغذية

Dear Sir or Madame,

first of all I would like to congratulate you to this very comprehensive report on a very relevant aspect. While reading it, I noticed that you focus entirely on the water footprint according to Hoekstra and colleagues when it comes to assessing the amount of water consumed in food production.

While this approach developed by the Water Footprint Network is well known, easy to understand, and well established, I would like to draw your attention to the limitations and drawbacks of such a volumetric method. Simply aggregating volumes of blue, green, and gray water fails to a address the much more relevant dimension of water use: the local impacts resulting from it. Obviously 1 m³ of rain water consumption in Brazilian soy bean production does not compare to 1 m³ of ground water consumption in Spanish tomato production. Consequently, these volumetric figures can be drastically misleading, as products with smaller volumetric footprints in water scarce regions can actually cause more severe consequences than product which consume more water in water abundant areas.

The understanding of the scientific community (including the Water Footprint Network) is that the determination of water consumption volumes is the first step only. Subsequently, the volume of water consumed needs to be interpreted based on parameters like local scarcity, sensitivity of ecosystems, ability of the population to compensate water stress, etc. Attached you can find a position paper of the UNEP/SETAC Life Cycle Initiative’s working group on water use in LCA (WULCA)  regarding the consideration of water use and associated impacts along product’s life cycle.

Further, I would like to mention that an ISO standard (ISO 14046: http://www.iso.org/iso/catalogue_detail?csnumber=43263) has been launched this year, which represents the international consensus on how water should be assessed along product life cycles. According to this standard a water footprint is a “metric(s) that quantifies the potential environmental impacts related to water”. Hence, a purely volumetric analysis of the amount of water used or consumed can be termed a water inventory but not a water footprint. This is in conflict with statement in you draft, which states: “The water footprint of a product is defined as the total volume of fresh water that is used directly or indirectly to produce the product” (Page 47, Line 11)

By assessing impact resulting from water use, the water footprint has developed from an inventory to an impact oriented indicator. In that way it is consistent with the carbon footprint, in which various greenhouse gas emissions are weighted according to their environmental relevance. In the same way that GHG emissions can be multiplied by a factor denoting the specific global warming potential, water consumption in different regions can be multiplied by a factor denoting the regional scarcity and sensitivity.

I my opinion your report, that will be of high relevance, should reflect the scientific development which has taken place during the last years. These new aspects can also be integrated quite easily into the existing version I think. If it can be of help, I can also assist you in this respects and make a few proposals.

Kind regards from Berlin,

Markus Berger