Trailwriter is correct. Want to make an actual impact? Ban bag distribution at the store level. Grocery stores in England, even as recently as the mid-80s, didn't provide any bags -- quite a shock to me as an American visitor buying groceries! But I quickly bought a carrier bag and brought it with me, every time.

From MSNBC: "— Paper bags generate 70 percent more air pollutants and 50 times more water pollutants than plastic bags.
— 2,000 plastic bags weigh 30 pounds, 2,000 paper bags weigh 280 pounds. The latter takes up a lot more landfill space.
— It takes 91 percent less energy to recycle a pound of plastic than it takes to recycle a pound of paper. It takes more than four times as much energy to manufacture a paper bag as it does to manufacture a plastic bag."

The idea of swapping plastic for paper is a typical knee-jerk reaction that doesn't come down on the green side of the equation.