Virtual water flows and footprints of agricultural goodsM. Fader, D. Gerten, J. Heinke, H. Lotze-Campen, W. Lucht, W. Cramer; Potsdam Institute for Climate Impact Research

Goal: Global analysis of virtual water and virtual land trade; water and land savings through trade; and internal/external blue/green water footprints.

Blue internal water footprints per capita

From Fader et al. 2011: Internal and external green-blue agricultural water footprints of nations, and related water and land savings through trade . Hydrol. Earth Syst. Sci. Discuss., 8, 483–527, 2011, http://www.hydrol-earth-syst-sci-discuss.net/8/483/2011/hessd-8-483-2011.html. Contact: mfader@pik-potsdam.de

Green internal water footprints per capita

Tool: Dynamic global vegetation and water balance model LPJmL (resolution 0.5°; period 1998-2002). Based on 11 crop functional types (temperate and tropical cereals, maize, rice, temperate and tropical roots, rapeseed, groundnuts, soybeans, pulses, sunflower). Trade data from COMTRADE, population data from IIASA.

Blue external water footprints per capita

Green external water footprints per capita

Main conclusions: 1) Green water globally dominates both the internal and external WFP (84% of the global WFP and 94% of the external WFP rely on green water). 2) The external WFPs are rather small (6% of the total global blue WFP, 16% of the total global green WFP). 3) Countries with high per capita water consumption affect mainly the water situation in their own country. 4) Trade saves ~263 km3 water and ~41 Mha land.

Definitions: Blue water: irrigation water; green water: precipitation stored in unsaturated soil. External water footprint (WFP): water consumed in other countries to produce goods imported to a country C; internal WFP: water consumed in C for products consumed in C. Savings: water/land resources saved through import of agricultural goods (i.e. water/land that would have been needed to produce these goods in C).

Water savings Land savings