In 2008, the city of Barcelona ran short of water; several shiploads of water were imported from Marseille to supplement the Barcelona city supplies during the summer months. This news attracted a lot of attention, and the media as well as the world became aware of the gravity of the water issue like never before.

But this story also diverted from the real issue – the water needed to grow food for an increasing world population. Seventy per cent of all freshwater withdrawn for human use goes into agriculture, as producing one calorie for an average diet requires one litre of water. Water stress and shortage, falling tables of underground aquifers and rivers running dry for ever-longer periods over the year will therefore, in the first instance, endanger the production of basic foodstuffs.

In 2003, Frank Rijsberman, the then-head of the International Water Management Institute, formulated what this could mean: ‘If present trends continue, the livelihoods of one-third of the world's population will be affected by water scarcity by 2025 … We could be facing annual losses equivalent to one-third of global grain crops today.’ A map published by the UN in 2006 shows where the problems lie currently: in the US Great Plains, the Middle East and North Africa, and parts of Spain, Pakistan, North-Western India and North-Eastern China. These are all important agricultural production areas.