Projected water consumption in future global agriculture: Scenarios and related impacts Stephan Pfister a, b, ⁎ , 1 , Peter Bayer c , Annette Koehler a , Stefanie Hellweg a a ETH Zurich, Institute of Environmental Engineering, 8093 Zurich, Switzerland b UC Santa Barbara, Bren School, Santa Barbara, CA 93106-5131, United States c ETH Zurich, Geological Institute, 8092 Zurich, Switzerland abstract article info Article history: Received 7 March 2011 Received in revised form 6 July 2011 Accepted 6 July 2011 Available online xxxx Keywords: Land use Water consumption Water stress Land stress Future scenarios Water footprint Global stress on water and land resources is increasing as a consequence of population growth and higher caloric food demand. Many terrestrial ecosystems have already massively been degraded for providing agricultural land, and water scarcity related to irrigation has damaged water dependent ecosystems. Coping with the food and biomass demand of an increased population, while minimizing the impacts of crop production, is therefore a massive upcoming challenge. In this context, we developed four strategies to deliver the biotic output for feeding mankind in 2050. Expansion on suitable and intensification of existing areas are compared to assess associated environmental impacts, including irrigation demand, water stress under climate change, and the productivity of the occupied land. Based on the agricultural production pattern and impacts of the strategies we identified the trade-offs between land and water use. Intensification in regions currently under deficit irrigation can increase agricultural output by up to 30%. However, intensified crop production causes enormous water stress in many locations and might not be a viable solution. Furthermore, intensification alone will not be able to meet future food demand: additionally, a reduction of waste by 50% along the food supply chain or expansion of agricultural land is required for satisfying current per-capita meat and bioenergy consumption. Suitable areas for such expansion are mainly located in Africa, followed by South America. The increased land stress is of smaller concern than the water stress modeled for the intensification case. Therefore, a combination of waste reduction with expansion on suitable pastures generally results as the best option, along with some intensification on selected areas. Our results suggested that minimizing environmental impacts requires fundamental changes in agricultural systems and international cooperation, by producing crops where it is most environmentally efficient and not where it is closest to demand or cheapest. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Agricultural production is currently accountable for 85% of global water consumption (Shiklomanov and Rodda, 2003) and projected to double by 2050 (Tilman et al., 2002). Irrigated area is expected to rise by a factor of 1.9 by 2050, while climate change is amplifying water stress by changing patterns of water availability in many parts of the world (Lobell et al., 2008). Finally, global production of biological energy resources is expanding and accelerates growth of agricultural production (Melillo et al., 2009). As a consequence of these pressures, water scarcity and land clearing represent major environmental concerns worldwide. The environmental impacts of water consumption and water stress are manifold. While aquatic and water dependent organisms are directly affected by water abstraction, there are also significant indirect effects. For instance, terrestrial ecosystems downstream of the location of water use may suffer from water stress through reduced natural water availability and groundwater drop (Maxwell and Kollet, 2008; Costanza et al., 2007). Agricultural land transfor- mation and occupation have direct ecological impacts on sites as well as on the surrounding landscape (Köllner, 2000). Generally, crop production deprives the land of most of its ecological value, e.g. through biodiversity degradation and disturbance of ecosystem functions. Coping with population growth as well as additional per-capita food demand represents a major challenge in feeding humanity in the future: The world average caloric intake of about 2800 kcal per person-day in the year 2000 is judged adequate for average activities (Lundqvist et al., 2008). However there are still about 570 million people living in countries with an average of less than 2200 kcal per person-day, which is considered the minimal amount to meet basic nutritional needs (Loftas and Ross, 1995). Clearly, this situation needs to be improved, while at the same time taking care that the impact on the environment remains limited. Science of the Total Environment xxx (2011) xxx–xxx ⁎ Corresponding author. Tel.: +41 44 633 75 71; fax: +41 44 633 15 79. E-mail address: stephan.pfister@gmail.com (S. Pfister). 1 Present address: UC Santa Barbara, Bren School, Santa Barbara, United States. STOTEN-12770; No of Pages 11 0048-9697/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.scitotenv.2011.07.019 Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv Please cite this article as: Pfister S, et al, Projected water consumption in future global agriculture: Scenarios and related impacts, Sci Total Environ (2011), doi:10.1016/j.scitotenv.2011.07.019