Reply to Pfister and Hellweg: Water footprint accounting, impact assessment, and life-cycle assessment

In response to our article on the blue and green water footprint (WF) of bioenergy (1), others propose to multiply each blue WF component by a water-stress index and neglect green WFs, because impacts would be nil (2). They propose to redefine the WF from a volumetric measure to an index resulting from multiplying volumes by impact factors. Framing their argument within the logic of life-cycle assessment (LCA), they ignore the primary and established role of the WF in water-resources management (WRM). Redefining the WF does not make sense from a WRM perspective, which requires spatially and temporally explicit information on WFs in real volumes and impacts in real terms.