The current global economic system is primarily based on the availability of relatively cheap, energy-dense and easily transportable hydrocarbon fuels -- namely oil. Scientists and analysts across a broad spectrum of backgrounds and beliefs agree that the world's supply of cheap oil is coming to an end relatively soon. Though they might disagree on the speed with which this change will occur, most agree that once it arrives, this change from inexpensive oil to ever more expensive and scarce oil will have far-reaching impacts on every aspect of our society.
Transportation systems will be the ones impacted first and most directly as they are the most dependent upon low-weight, energy-dense fuels such as oil. The effects of those changes to our transportation systems will ripple outward, impacting how and from where we get our food, the availablitity of manufactured products and replacement parts, how far we can afford to live from our place of work, etc. The list of possible consequences is very long indeed.
One thing is for sure: communities will eventually need to restructure how they provide for their most basic needs. And since making those kinds of major changes can take a long time, there's no sense in waiting until the last minute. Regardless whether we have only a few years until the price of oil dramatically impacts society, or 20 years, there's no time to waste. We need to begin making other arrangements today at the local level.