You might think that falling gasoline prices would be welcome news to the left. Cheaper gas brings down the cost of everything which is a special boon to the poor. It also reduces the cost burden of businesses which enables them to hire more people. Moreover, the reasons for the lower prices - the natural gas boom at home and the slowdown in petroleum demand worldwide because of cooling economies in India and China and difficulties in Europe - means that less carbon is being thrown into the atmosphere. All of this should be welcome news to the left, but it's apparently not.
The problem, as they see it, is that if gas is relatively cheap, then alternative fuels will not be competitive and there'll be little to no incentive to move toward developing them. Thus, lefties like those in the piece at the link believe we need to artificially make fossil fuel more expensive by imposing a hefty tax on carbon consumption.
The left doesn't seem to care much that such a tax will severely hurt the poor and middle class, stifle job creation, and smother any chance of an economic recovery. What they care about is making fossil fuels economically impractical and whoever has to be sacrificed to get to that goal is evidently expendable.
Cheap fuel is a blessing for everyone, but especially for the "little guy." If we really care about him we'd be a lot more reluctant to make his life harder than it already is.