Conclusions
Proponents claim that banning plastic shopping bags will benefit the environment. Yet, as this study has shown, there is very little empirical support for such claims. Indeed, the evidence seems to point in the other direction for most environmental effects. Some of the alleged benefits are simply false, such as the claim that eliminating plastic bags will reduce oil consumption. An assessment of the San Francisco ban on plastic bags suggests that while there may have been a very small reduction in the amount of litter generated, some emissions—such those of greenhouse gases—may well have increased as a result of the ban.
At the same time, concern about the environment is only one of many issues affecting consumption choices. When it comes to shopping bags, the look, feel, and—likely most important for the majority of consumers—function are very important. HDPE plastic bags are strong, light and highly convenient (there is no need to remember to take them along when shopping, since they are supplied by the store). Also, they are typically reused for various purposes. These features have made them very attractive to consumers. By contrast, reusable NWPP bags are bulky (causing inconvenience when shopping), must be washed between shops if they may have come into contact with harmful bacteria, and must be remembered prior to going shopping (making them far less convenient); moreover, households using NWPP bags will typically purchase more garbage bin liners.
In spite of widespread media attention to the largely false claim that plastic bags are environmentally harmful, bans on the use of plastic bags are not popular: A recent Reason-Rupe poll showed that 60% of Americans oppose plastic bag bans, while only 37% are in favor. Opposition is non-partisan, though it is stronger among independents (64%) and Republicans (71%) than Democrats (52%).
Environmental groups that really care about the problem of litter, such as Keep America Beautiful, have generally promoted solutions that substantially reduce the amount of litter generated, such as public information campaigns focused on litter reduction, and facilitating clean-up operations. In other words, they target littering behavior, which is the actual cause of litter, rather than opposing the existence of certain types of product that might become litter. Meanwhile, environmental groups that really care about the protection of marine animals know that litter is not the prime culprit of diminished marine life and generally focus on other issues, such as policies that promote overfishing.
Unfortunately, policymakers have been cajoled into passing ordinances that ban plastic bags. That is bad news for consumers. It is also bad news for the environment, since the public has been misled into believing that by restricting the use of plastic bags, the problems for which those bags are allegedly responsible will be dramatically reduced. As a result, they are less likely to undertake activities—such as reducing littering and supporting policies that would lead to better protection for marine animals—that would actually benefit the environment.