Mr research said: That the same number of paper grocery bags uses five times MORE total energy to produce and use. A paper grocery bag isn't just made out of trees. Manufacturing 100 million paper bags with 1/3 post consumer recycled content requires petroleum energy inputs equivalent to approximately 15,100 barrels of oil (634K gal.) 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 paper bag (more than 20 times the amount used to make a plastic bag), it also 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.

We should all be required to use canvas/cloth bags.