The present water policy debate is dominated by the 30 yr old mission to secure water supply and sanitation to all people. The water needed to produce a nutritionally acceptable diet for one person is however 70 times as large as the amount needed for domestic water supply. The food security...

Water security needs priority in adaptation to global change. Most vulnerable will be the semi-arid tropics and subtropics, home of the majority of poor and undernourished populations. Policies have to distinguish between dry spells, interannual droughts and long-term climate aridification. Four...

Agricultural systems as well as other ecosystems generate ecosystem services, i.e., societal benefits from ecological processes. These services include, for example, nutrient reduction that leads to water quality improvements in some wetlands and climatic regulation through recycling of...