Denver takes the lead … will Chicago be next:

Denver is gearing up to fight global warming, and residents may soon be asked to make personal sacrifices to help save the planet.

The new plan is aimed at making Denver a national leader in reducing gas emissions that have been linked to global warming, giving a major push to alternative energy, stepping up recycling and changing building codes to encourage energy conservation.

But the proposal also contains some ideas that may be unpopular, such as penalizing heavy users of electricity and natural gas and basing auto insurance premiums on the number of miles traveled.