In March, New York became the second state to ban plastic bags—behind California, which banned them in 2016. Countless cities, towns, and counties have also either prohibited plastic bags or imposed fees or other restrictions on their use.

As always, New York's ban was justified as a way to protect the environment. Gov. Andrew Cuomo declared that it will "reduce litter in our communities, protect our water and create a cleaner and greener New York for all."

Or maybe it won't. Far from weening us off hazardous single-use plastics, these bans may actually be encouraging people to instead use thicker garbage bags or other less-than-green alternatives.

So says a study from the University of Sydney economist Rebecca Taylor. She looked at retail scanner data on the purchase of garbage bags in cities before and after they implemented their bag bans. She found that while plastic bag bans got rid of their target, they did not eliminate people's need for plastic bags in general: They still needed something to line their garbage cans or pick up after their pets. Prior to bag bans, this could mean just reusing the bags you carried your groceries home in. After the bans, folks turned to purchasing garbage bags, which are much more plastic-intensive.

They bought lot of them. Taylor's study found that after the imposition of a bag ban, sales of small garbage bags (defined as 4-gallon-sized bags) increased by a full 120 percent, medium garbage bags (8 gallons) by 64 percent, and tall bags (13 gallons) by 6 percent.

The result? There was a 40 million pound drop in the consumption of normal carryout bags, but the consumption of garbage bags rose by 12 million pounds, erasing about 30 percent of the gains from the bag ban.

This unintended consequence is reminiscent of coffee chain Starbucks' attempt to cut down on plastic usage by replacing the traditional lid/straw combo that tops many of their cold drinks with new strawless lids. The trouble, as Reason first reported, is that the new lids weighed more, meaning that Starbucks' shift has resulted in the company using more plastic.

Taylor's findings are not so damning for plastic bag bans on that front. Overall plastic consumption is still coming down.

But Taylor's study also notes that many non-plastic replacements for traditional plastic grocery bags can in fact be far worse when considering their impact on climate change. "To have the same global warming potential as a traditional plastic carryout bag with zero secondary use, a paper carryout bag would need to be used 3 times, a non-woven polypropylene (PP) reusable bag would need to be used 11 times, and a cotton reusable bag would need to be used 131 times," she writes.

All prohibitions have unintended consequences, and that includes prohibiting plastic products.