Plastic, paper, or cotton bags?

NPR Planet Money: Are Plastic Bag Bans Garbage?

“It was only about 40 years ago that plastic bags became standard at U.S. grocery stores. This also made them standard in sewers, landfills, rivers and the Great Pacific Garbage Patch. They clog drains and cause floods, litter landscapes and kill wildlife. The national movement to get rid of them is gaining steam — with more than 240 cities and counties passing laws that ban or tax them since 2007. New York recently became the second U.S. state to ban them. But these bans may be hurting the environment more than helping it.
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Plastic haters, it’s time to brace yourselves. A bunch of studies find that paper bags are actually worse for the environment. They require cutting down and processing trees, which involves lots of water, toxic chemicals, fuel and heavy machinery. While paper is biodegradable and avoids some of the problems of plastic, Taylor says, the huge increase of paper, together with the uptick in plastic trash bags, means banning plastic shopping bags increases greenhouse gas emissions. That said, these bans do reduce nonbiodegradable litter.
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A 2011 study by the U.K. government found a person would have to reuse a cotton tote bag 131 times before it was better for climate change than using a plastic grocery bag once. The Danish government recently did a study that took into account environmental impacts beyond simply greenhouse gas emissions, including water use, damage to ecosystems and air pollution. These factors make cloth bags even worse. They estimate you would have to use an organic cotton bag 20,000 times more than a plastic grocery bag to make using it better for the environment.”