Letter to the editor re: “The scarcity-weighted water footprint provides unreliable water sustainability scoring” by Vanham and Mekonnen 2021

In their recent paper “The scarcity-weighted water footprint provides unreliable water sustainability scoring”, Vanham and Mekonnen criticize scarcity-weighted water footprints as “contraproductive for achieving SDG target 6.4”. Unfortunately, the paper is another example of an unproductive dispute between the life cycle assessment (LCA) and water footprint (WF) communities, which mainly deals with the question whether the water footprint should be a volumetric or environmental impact-based indicator. In the past, this led to a series of “reply to” papers such as Hoekstra et al. (2009) replying to Pfister and Hellweg (2009) commenting on Gerbens-Leenes et al. (2009), or Hoekstra and Mekonnen (2012b) replying to Ridoutt and Huang (2012) criticizing Hoekstra and Mekonnen (2012a). As recently stated in Gerbens-Leenes et al. (2021), we agree that this conflict between the communities has been unhelpful, even if science needs a debate. Authors of this letter to the editor have been involved in several discussions leading to the recognition of the complementarities of the two approaches (Boulay et al. (2013), Gerbens-Leenes et al. (2021), Boulay et al. (2021) and continue to strive for scientific relevance in the use of different approaches. This paper aims at 1) clarifying methodological misunderstandings concerning impact-based water scarcity footprints, 2) revealing methodological flaws in the analysis of Vanham and Mekonnen (2021), and 3) showing that volumetric and impact-based water footprints can answer relevant but different questions related to water use along supply chains. Finally, to not leave this conversation hanging and pursue further collaboration, we invite the authors and all researchers involved in water footprinting to a workshop where both communities can discuss differences and, even more so, the complementary strengths of both approaches.

PFISTER Stephan;  SCHERER Laura;  BOULAY Anne-Marie;  MOTOSHITA Masaharu;  NÚÑEZ Montserrat;  DAMIANI Mattia;  MANZARDO Alessandro;  HUANG Jing;  LINK Andreas;  BUNSEN Jonas;  BERGER Markus; 

2022-05-18

ELSEVIER

JRC126657

0048-9697 (online),   

https://www.sciencedirect.com/science/article/pii/S0048969722012001,    https://publications.jrc.ec.europa.eu/repository/handle/JRC126657,   

10.1016/j.scitotenv.2022.154108 (online),