In response to the debate around paper vs plastic as a result of San Francisco's ban on plastic bags. Keep in mind that not only are plastic bags better on all environmental fronts, but this article is comparing the effect in a 2:1 ratio, because of the capacity of plastic bags. When discussing using the bags under maximum capacity, Plastic blows paper away in all fronts.

There is no environmental reason to use paper over plastic. All it does in contribute to the cloud of smug looming over San Francisco (south park reference).

Quoted: Through a lifecycle energy analysis, plastic is the better bag. At current recycling rates two plastic bags use less energy and produce less solid, atmospheric, and waterborne waste than a single paper bag.