Green Daily

FOOD: We've also entered an age of newly expensive food. While most North Americans can handle a 50 cent increase in the price of a loaf of bread or a bowl of rice, a jump like that can mean no meals at all in a place where the average income is about 2 bucks a day. One of the causes of the crisis is skyrocketing oil prices (see above), which increase the cost of chemical fertilizers, farm machinery, and food distribution. Could it get worse? Paul Roberts, author of The End of Food, offers a casually terrifying scenario, noting that "a peak in oil output, and the subsequent decline in food supplies, would shrink the global population by several billion over the next two decades."

It's not just oil of course . Food production is also affected by an increasingly unpredictable climate, loss of arable land, diversion of crops to biofuels,changing eating habits in Asia, and of course population growth , with about 2 billion new people expected to arrive on-planet in the next 2 decades. And lets not forget the collapsing fisheries.

METALS: The industrial revolution was built on steel - steamships, railways, and factories. The information revolution has largely been constructed on highways of copper, a superb conductor of electricity that's used in phones, computers, and every kind of communications network.

Both of these metals have leapt in price in the last few years, with the price of iron ore used to make steel jumping 65% this year alone. The copper situation is even worse - prices have shot up so quickly that thieves are frying themselves breaking into electrical substations and yanking out live wires to sell to junk dealers. What's more, a 2006 study estimated that all the copper currently in use, plus all that's in the ground waiting to be dug out, isn't nearly enough to bring developing countries up to first world standards of living. Hang on to those old pennies, folks.

There are other metals out there in short supply too - zinc, lead, platinum - but copper is the one that could shut down the global village fastest.

WATER: The 21st century may be defined by conflict over water. Climate change is causing droughts of historic proportion in the western US, as well as parts of Africa, Europe and Asia. Increased consumption is also a big driver, with water consumption increasing sixfold in the last century and expected to double again by 2050. Pollution is also a problem, as some places have water but it's so toxic that it can't be used for basic human needs.

H2O is fundamental to human life, and unless we can figure out how to get a handle on the problem, expect wars over water usage, and massive migration from places that don't have enough water to places that do. Like your bathroom.

All these problems, of course are highly interrelated. An output on one side - say, water - is an input for mining, oil drilling and agriculture. We can't simply look at one issue without considering the larger question of why our society is outstripping its resource base so rapidly. Ultimately we have to address the underlying causes of the problem - climate change, population growth, and our collective propensity for stupidity, selfishness and waste.

With luck, over time technology will find answers in the form of new sustainable energy sources, more effective recycling, desalination plants for water, and better ways of growing food. But there are likely to be some big bumps in the road before we get there.