There are those who believe that a switch to paper bags from plastic bags will yield strong environmental and waste management benefits. But the science shows that is not the case.
Trees Are the Lungs of Life
The raw materials for paper bags have to come from trees, a natural resource that are not only one of our greatest tools for fighting pollution but are also the lungs of life. Trees are carbon sinks that absorb carbon dioxide and produce oxygen.
In the production of paper bags, forests, which are major absorbers of greenhouse gases, have to be cut down, and then the ensuing manufacturing of bags produces greenhouse gases resulting in a double whammy to the environment.
Trees are important tools in the battle against climate change.
Science Tells the Story
Every scientific study undertaken shows that conventional plastic shopping bags are better for the environment – on manufacturing, on reuse, and on solid waste volume and management.
Three independent Life Cycle Assessments (LCAs) of plastic shopping bags and their impact on the environment have been conducted recently by governments – the U.K. Government, the Government of Denmark and the Province of Quebec.
All three scientific LCA studies were unanimous in their conclusion that plastic shopping bags, based on how they are used by consumers, are the best bag for the environment. All LCAs show scientifically that a ban on plastic shopping bags will actually harm the environment.
The Quebec Government LCA found that: “No replacement option has an environmental advantage in the event of a ban on plastic shopping bags.” The most interesting study finding is that the conventional, thin plastic shopping bag is not a single-use bag because it has a very high reuse rate at 77%. Related to paper bags, they stated: “The paper bag is the least performing bag with 4 to 28 times greater potential impacts than the conventional plastic bag.” (Page 61)
The Government of Denmark LCA found that paper bags should be reused and up to 43 times considering all other indicators.
The UK Life Cycle Assessment also found that conventional plastic shopping bag (HDPE) outperformed all alternatives, even reusables, on environmental performance. They have a much lower global warming potential. Paper bags would have to be used three times to lower their global warming potential to match that of a conventional HDPE plastic shopping bag being used just once.
More Detail on Why Plastic is Better than Paper Environmentally
On Solid Waste
Volume & Tonnage Impact
The most significant and immediate impact of a switch from plastic shopping bags to paper grocery bags is the additional volume and tonnage that paper adds to the waste stream. This additional volume correlates directly to significant increases in the amount of greenhouse gas emissions produced to transport it.
A switch to paper will generate more waste – there will be an increase in both the volume and tonnage of material entering the waste stream by seven times because paper is so much heavier and occupies more space because it is bulky.
Kraft paper bags weigh 55 grams; seven times more than conventional plastic bags which weigh 8 grams.
It takes seven trucks to transport 2 million paper bags versus one truck to carry 2 million plastic bags (Source: Bag Manufacturers Producing Plastic & Paper Bags).
Solid Waste Environmental Impact
A switch to paper will generate seven times the greenhouse gas emissions from the additional trucks needed to ship the paper to facilities and manage it in the waste and recycling streams.
Plastic bags outperform paper bags. Paper bags are not as durable or strong. They tend to fail on reuse because they tear easily and cannot handle wet weather conditions.
What does the data tell us? The Ontario Ministry of the Environment audit data that tracks the province’s 50% bag reduction program shows a 59.1% alternate (reuse) rate for plastic shopping bags; 77% in Quebec; and 91% in Manitoba.
Both bags are highly recyclable. Paper tends to have a higher recycling rate than plastic because paper bags are not highly reused. Around 30% of plastic shopping bags are recycled in curbside and take-back-to-retail programs. The Ontario Ministry of the Environment’s 2010 report on the 50% Plastic Bag Reduction Program determined a 36% recycling rate in municipalities recovering bags in the blue box.
The reason why the recycling rate is not higher is that conventional plastic shopping bags have very high reuse rates across Canada.
The Quebec Government LCA identified a 77% reuse rate; the Ontario Government Bag Reduction Task Force tracked a 59.1% reuse rate; and Multi-Material Stewardship Manitoba (MMSM) has reported a 90%+ reuse rate for plastic shopping bags in their province.
The primary secondary reuse is to use conventional plastic shopping bags as a replacement for kitchen catchers to manage household waste (source: CROP Poll) and what is left over is recycled.
Paper bag manufacture is much more resource-intensive than plastic bag manufacture.
Scientific study after scientific study makes the case.
According to the Scottish government’s 2005 Report on Plastic Shopping Bags, the manufacture of paper bags consumes four times more water than the manufacture of plastic bags and paper generates three times more greenhouse gases.
The EcoBilan Carrefour Life Cycle Assessment shows that in their manufacture, paper bags consume 2.2 times more non-renewable energy than the manufacture of plastic bags; paper bag manufacture consumes 4.7 times more water, emits 3.1 more greenhouse gases and 2.7 times more acid gases than the manufacture of plastic bags.
The U.K. Government Life Cycle Assessment found that paper has a greater negative impact as noted below. It consumes 4 times more water, emits 3.3 times more greenhouse gases and 1.9 times more acid rain.
For more information go to Bag Science.