This Synthesis Paper contains a necessarily rapid appraisal of the implications of the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (AR4-IPCC) for agricultural water management and, based on that evidence, offers a more operationally focused diagnosis. It provides a summary analysis of a baseline, including projected trends without climate change and mitigation measures; the anticipated set of climate change impacts; a set of possible responses; main findings and recommendations; and a set of options for decision-makers.