Reason Foundation's Skaidra Smith-Heisters asks paper or plastic? And the environmentally-friendly answer may surprise you:
"One hundred million new plastic grocery bags require the total energy equivalent of approximately 8300 barrels of oil for extraction of the raw materials, through manufacturing, transport, use and curbside collection of the bags. Of that, 30 percent is oil and 23 percent is natural gas actually used in the bag-the rest is fuel used along the way. That sounds like a lot until you consider that the same number of paper grocery bags use five times that much total energy. A paper grocery bag isn't just made out of trees. Manufacturing 100 million paper bags with one-third post-consumer recycled content requires petroleum energy inputs equivalent to approximately 15,100 barrels of oil plus additional inputs from other energy sources including hydroelectric power, nuclear energy and wood waste.
Making sound environmental choices is hard, especially when the product is 'free,' like bags at most grocery stores. When the cashier rings up a purchase and bags it in a paper bag, the consumer doesn't see that it took at least a gallon of water to produce that bag (more than 20 times the amount used to make a plastic bag), that it weighed 10 times more on the delivery truck and took up seven times as much space as a plastic bag in transit to the store, and will ultimately result in between tens and hundreds of times more greenhouse gas emissions than a plastic bag."