In Vermont, a progressive haven, emissions spike forces officials to consider drastic action

It’s a state that prides itself on purity: its pristine land, progressive politics, even its ice cream.

So it was no surprise when Vermont sought to lead the way in cutting carbon pollution, vowing to reduce greenhouse gases from the state’s power plants, cars, and other sources by 25 percent below 1990 levels by 2012 and 50 percent by 2028.

Those goals, set by lawmakers in 2005, were significantly more aggressive and made before similar pledges in Massachusetts and other states.