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The Top 10 Green Issues of 2008

Have we reached peak oil?
Peak oil could happen sooner rather than later.
Peak oil could happen sooner rather than later.
Don Farrall/Photodisc/Getty Images

Eventually we're going to run out of oil. No, it won't be that your car just sputters to a stop one day, or the tune-up station shutters its windows forever, but it will happen, and we might already be halfway there. Peak oil is the theoretical point when the Earth's oil supply begins an irreversible downward descent -- when oil demand outpaces production. Most folks agree that there will be a peak, but there are lots of opinions about when that peak will be: now, soon or a ways down the road.

What's so scary about a potentially imminent peak in oil supplies? Currently, we don't have the capacity to make up for a major loss in oil production with alternative fuels. A peak could also drive oil companies to drill in protected places to slurp up the Earth's remaining fuel.

­Mitigation seems to be the best way to cope with the tap eventually trickling to a stop. By expanding the supply of alternative liquid fuels and conserving the oil we have through increased fuel efficiency, we're more likely to weather what might be a slippery transition. Find out more about the theory in Have we reached peak oil?

If you haven't gotten your fill of 2008 or the topics above, go to the next page to find out more. ­