Recent research by a graduate student at Stanford University in California has some interesting results. It showed that single-use plastic bags have the smallest carbon footprint.
An Environmental Agency (U.K.) report from 2011 found that paper bags must be reused at least three times to negate their higher climate-warming potential (compared with that of plastic bags). A cotton bag would have to be reused 131 times to break even with a plastic bag, in terms of the climate impact of producing each bag.
Of course, plastics can be reused as well — they just don’t look as trendy. So now, do you still want to ban plastic bags?