"THE era of cheap food is over. The price of corn (maize) has doubled in a year, and wheat futures are at their highest in a decade. The food price index in India has risen 11 percent in one year, and in Mexico in January there were riots after the price of corn flour (used in making the staple food of the poor, tortillas) went up fourfold.
Soaring Asian demand and bio-fuels mean expensive food now and in the near future, but then it gets worse. Global warming hits crop yields, but only recently has anybody quantified how hard. The answer, published in Environmental Research Letters in March by Christopher Field of the Carnegie Institution in Stanford, California and David Lobell of Lawrence Livermore National Laboratory, is quite simple: for every 0.5C (0.9F) hotter, crop yields fall between three and five percent. So two degrees C hotter (3.6F), the lower end of the range of predicted temperature rise in this century, means a 12 to 20 percent fall in global food production. This is science, of course, so that answer could be wrong — but it could be wrong by being too conservative.
The price of food relative to average income is heading for levels that have not been seen since the early 19th century, and it will not come down again in our lifetimes."
Sorry to act like a doomsayer, but I cant help pointing this out. Read this excellent summary