Nestle is not known for its ethical stance. In fact the company has long been a target for campaigners due to its promotion of baby milk products in the third world.

So it is surprising that its chairman, Peter Brabeck-Letmathe, has been making a stand. He is calling for action over the way the world wastes water, and warns that a lack of water will affect us more seriously, and sooner, than a lack of fuel.

The focus is on agriculture. Every calorie of plant matter we consume takes about one litre of water to grow. That goes up to ten litres for meat. So we are each using around 3000-6000 litres a day for our food, compared to a tenth of that for washing and drinking.

The wasteful way much of the world's fields are irrigated means much of this could be saved. But a new threat is biofuels. It takes about 13,000 litres to produce and convert a litre of bioethanol. This is simply not possible for the long term. It is yet another reason why biofuels will not be the answer to the energy crisis.

The answers lie in energy conservation and renewable power. These are the areas that should be quickly developed so that we can face the challenges on the horizon.