Green water security for the food makers of tomorrow: windows of opportunity in drought-prone savannahs

The largest remaining biophysical water challenge is whether there is enough fresh water to sustain global food production and service natural ecosytems. Focussing on the drought-prone savannahs and small-scale farming, this paper argues that the crucial resource is vapour flow, not "blue" water, and there are grounds for optimism if resource management can be improved.