In 2001 a number of agricultural research scientists were briefed to investigate future world food production. At the same time a group of UN scientists embarked on an assessment of the likely economic and social impacts of water shortages in developing nations, while a third group, representing major water, oil and chemical companies, looked at the influence of water scarcity on company and national economic performance.

When the three reports were published they painted a picture of future supply disruption and economic crises unless the way the world uses water changes dramatically. Demand for clean water is expected to increase by 100 per cent between 2007 and 2040, largely because of urbanisation and industrialisation. In other words, we are at the very edge of sustainability, even before the effects of climate change are factored in.

However, the good news is that solutions are neither costly nor difficult. Growing drought-resistant varieties of crops and shifting consumer demand away from ‘thirsty’ foods, for instance, would save an enormous amount of water and would be a far better investment than expensive dams and pipe networks. Farming using irrigation, for example, uses over 60 per cent of all water taken from rivers and aquifers globally, and while the world grows twice as much food as it did a generation ago we use three times as much water to do it.

To produce a single kilogram of rice, for instance, requires between 2,000 and 3,000 litres of water. A kilogram jar of instant coffee takes 20,00 litres, a litre of milk 4,000 litres, a single hamburger 11,000 litres and a cotton T-shirt 7,000 litres of water. Other low-tech solutions include the increased use of grey water recycling and desalination (21 plants are already proposed in California alone). So in the future expect to see ordinary people becoming involved in the ‘ethics’ of water.

There will be new water taxes and consumer boycotts of companies that are profligate in their use of water or use cloud seeding unfairly. Finally it’s worth mentioning that water is potentially China’s Achilles heel. Four hundred out of China’s six hundred biggest cities are already short of water and the country has well below-average water resources per capita, which could potentially put a spanner in the works of China’s development model.