The debate over paper or plastic grocery bags has no apparent end in sight. Arguments can be made for either material as the most environmentally responsible one, but some have settled the issue by switching to reusable cloth sacks. While this solution may be elegant, most consumers are still confronted with the question whenever they shop for groceries. In order to decide between the two choices, it might help to examine what is meant by "better for the environment." Paper is more biodegradable, but requires trees to be cut down and processed. Plastic can take centuries to break down, but it makes less energy to produce.
Very few manufacturing processes have absolutely no negative impact on the environment. In the paper or plastic debate, paper is often promoted as the wiser choice for the environment because of its organic nature and biodegradability. Paper for grocery bags is created from natural wood pulp derived from an abundant supply of commercial trees. There are no artificial dyes added, and paper grocery bags degrade relatively quickly in landfills and other sites. From the aspect of biodegradability and raw materials, paper would appear to be better for the environment.
The paper bags must be manufactured somewhere, however, and that means factories that require significant amounts of energy to operate. These factories also discharge waste products into local waterways and into the air. Trees work as carbon dioxide traps and also provide a supply of fresh oxygen for all of the Earth's inhabitants. If the paper industry does not maintain a program of replacing the trees it uses for production, the environment as a whole could suffer. When it comes to responsible use of natural resources, biodegradable plastic may have a slight advantage.
Proponents of plastic grocery bags suggest that traditional petroleum-based plastics may not be as environmentally friendly as organic paper, but manufacturers can produce many more plastic bags for the same amount of expended energy. When factories are able to work more efficiently, the environment benefits as well. It takes fewer natural resources such as coal and gas to produce plastic bags in bulk, compared to the more labor-intensive manufacturing required to produce paper bags.
The problem with traditional petroleum-based plastic bags, environmentally speaking, is their chemical nature. Plastic bags can take centuries to degrade, and they discharge environmentally harmful gases as they do. The bags can also block sunlight, which can hamper the natural reclamation process as small plants die off. Recently developed biodegradable plastic bags made from non-petroleum sources have improved conditions somewhat, but there are still millions of traditional plastic bags sitting virtually unchanged under the ground.
Plastic bags are indeed recyclable, which should be a positive step for the environment, but few customers actually return their plastic bags to the store. Paper bags, on the other hand, may be made from recycled materials and waste pulp from other processes. When it comes to ability to be recycled, the paper or plastic debate leans towards paper. If a biodegradable plastic grocery bag made from organic materials should appear, however, the scales may become a little more balanced.
In short, paper bags in their current form seem to be better from an environmental standpoint, though anything that is not re-usable is taking its toll on our natural resources. Of course, once a suitable substitute for petroleum-based plastic can be found, the plastic bags of the future may be even better for the environment than paper or cloth bags are today.