It requires 50 litres of water to produce a single pack of lettuce, as stocked on the shelves of a typical high street supermarket. This is a striking reflection of the way modern western society squanders an increasingly precious resource, which along with oil will engender future conflicts and wars, as their supply dwindles in the face of a rising global population. I have written on the subject of water in a previous posting "Water Water Everywhere - but less than we think, in which I refer to the quantity of water that is used per day by the average citizen of various countries around the world: so, if an average American uses around 500 litres daily and a Britain about 150 litres, many in Africa have to get by on less than 10 litres a day. Hence, the production of a pack of lettuce in Kenya is equivalent to the daily water ration for five people. Shocking!
There is a growing appetite among western consumers for "out of season" products, rather than following the natural growing season as was the case certainly when I was a child. One even looked forward to particular favourites "coming into season" following the months during which they would ripen and fluorish. Apart from local "farmers' markets" this is largely no longer the case, and we expect to go into the local supermarket to buy whatever produce we like, whenever we want it, and at as low a price as possible. In the developing world, the production of cash crops is one of the few means out of poverty, although such activities run against the conflicting demands of globalisation and sustainability.
India is a good example, where major companies such as Coca-Cola (which used to contain cocaine in its original 19th century formulation) are encouraged to open factories which consume vast volumes of the available water, while at the same time small farmers are committing suicide in recored numbers, in the hopeless face of drought.
The main problem is our culture of convenience, also known as the "throw-away society" which along with the "disposable family" is hardly a route to great contentment or to sustainable lifestyles. Increasingly, our own home-grown fresh produce is bagged-up rather than being sold loose. I have often noticed that when the latter option is available, the price/kg reveals that the containment in the bag increases the price by anything up to five-fold. I always buy loose, as a matter of principle in equal measure with economic considerations. The bottled water industry transports millions of gallons of water between different countries: as world water shortages soar, "water" may become a major commodity, with the price of shares in it in the ascendent.
We can all sow the seeds by which to change this convenience culture, on a personal level, by encouraging demand for locally produced food and shunning that grown in an unsustainable fashion in the third world, thus sending the message to suppliers that a different kind of market is emerging. On both moral and economic grounds this must desist: the problems of water shortage are self-evident, and can only become more acute as global warming, drought and loss of clean water supplies occur through e.g. saline contamination as sea levels rise.
It is instructive to look on the packet and see where exactly particular crops were exported from, e.g. tomatoes from west Africa, which require the use of desalination plants to supply enough water to grow them, such is the pressure on this basic resource, which it has been said is "more precious than gold". Indeed it is so, since we can all live without gold, but not without enough clean water.
The acclaimed biologist Paul Erlich concluded in his book The Population Bomb, published forty years ago, that the world population was growing so fast that food production could not keep pace with it. The crash that he memorably forecast did not happen because of a combination of vast irrigation schemes that were introduced in the developing world, and cheap chemical fertilisers, derived from gas and oil. Today the world grows twice as much food as it did a generation back, but it requires three times as much water to do so. Around three quarters of all water extracted from the environment - from rivers, lakes and accessible aquifers - is used to irrigate crops. The situation cannot be maintained, and an increasing base level demand from numbers of population many of whom aspire to a western lifestyle will push humankind over the edge of stability. Undoubtedly wars will be fought over water, and as a salient example, the Egyptian government has threatened military action against any upstream country that dams the Nile or its tributaries, such is the country's economic dependence on exports of vegetables.
Particular environmental stresses on water are worth mentioning. To produce one litre of Coca-Cola requires three litres of water. Around one Coca-Cola bottling plant in India the water table has fallen by 10 metres since it opened, sucking local farms dry. In Ecuador, rose production with its attendent heavy use of pesticides, fungicides and herbicides has contaminated rivers and ground water with the loss of large numbers of animal and plant species, and tainting drinking water that people need. An explosion of coffee plantations in Vietnam has provided much needed fiscal wealth but water scarcities are now common both in terms of volume and contamination of what remains available. In China, paddy fields expel 2,000 tonnes of water for every tonne of rice they produce.
The implications for future rice provision are clear, since half the entire world's population will depend on rice by 2025, including the west which demands ever increasing amounts of this staple food.