Paper Bags Are Not Greener

Science does not support paper as a substitute for plastic bags

Ocean acidification and warming - paper bags product 4-7 times more carbon

Mostly ignored in the discussion of marine plastics is the very serious issue of the acidification and the warming of our oceans because they are having to absorb too much carbon from the atmosphere. The result is that as our oceans become warmer and more acidic putting marine animals and plant life at risk.

So why substitute carbon-heavy paper bags for plastic?

So why would any politician want to promote and adopt paper bags which have a carbon footprint 7 times greater than plastic shopping bags? Already ocean acidification and its warming poses serious challenges to the world’s coral reefs and the depletion of our fish stocks.

There is no scientific justification for substituting plastic bags with paper bags. It is actually anti-environmental.

It makes no environmental sense. Paper bags have a much higher carbon footprint. 

Paper bags weigh 56 grams on average versus a plastic shopping bag which only weighs 8 grams.  So it takes 7 trucks to transport 1 million paper bags but only 1 to transport 1 million plastic shopping bags. This translates into 7 times more carbon emissions.

Here's the Science

Every bit of science shows that plastic performs better than paper environmentally.

There is absolutely no scientific study that shows that paper better for the environment than plastic shopping bags.

Study after study proves that paper shopping bags have a higher global warming impact and much larger carbon footprint than plastic shopping bags.

Scientific Studies – In order of most important

Report Specifics

The Quebec Government LCA Recyc Quebec In Brief – January 2018

Environmental and Economic Highlights of the Results of the Life Cycle Assessment of Shopping Bags

English Highlights Report: https://monsacintelligent.ca/wp-content/uploads/2018/03/ENGLISH_FINAL-Quebec-LCA-Highlights.pdf

English Full Report: https://monsacintelligent.ca/wp-content/uploads/2018/03/ENGLISH_FINAL-Quebec-LCA-Full-Report.pdf

The Quebec Government’s Life Cycle Assessment (LCA) compared the environmental impact of all shopping bags available in Quebec in order to determine which bag has the lowest carbon footprint using North American data. The LCA was conducted by the International Reference Centre for the Life Cycle of Products, Processes and Services (CIRAIG), affiliated with Polytechnique Montréal.

The LCA showed beyond a shadow of a doubt that the plastic shopping bag is the best bag environmentally and economically.

Three key findings:

  1. The conventional plastic bag is not a single-use bag, but a multiple-use, multiple-purpose bag. The conventional plastic bag has a 77% reuse rate in Canada. Only 23% of the bags are single-use, and these bags can be recycled.
  2. It found that reusable bags have a much larger carbon footprint because they are heavier bags using more material. And reusable bags must be reused multiple times to match the much lower environmental impact of the conventional plastic bag used just once.
  3. Paper bags used to replace conventional plastic bags

According to the Quebec Government LCA, the Polypropylene (PP) woven and PP non-woven reusable bags need an equivalent number of reuses to equal the thin plastic bag ranging from 16 to 98 and 11 to 59 times, respectively, depending on the scenario and environmental indicator.

The report concludes that "no alternative to banning plastic bags offers an environmental benefit. ...] In this context, banning [thin HDPE bags] would not be advantageous." 

Denmark Government LCA Ministry of Environment and Food In Brief – February 2018

Life Cycle Assessment of grocery carrier bags

Click here for Denmark Report

The Government of Denmark LCA of grocery carrier bags found that conventional plastic shopping bags have the lowest environmental impact of all bags in their marketplace and that reusable bags have to be reused multiple times to provide the same environmental performance of the average conventional LDPE carry bag reused as a waste bin bag before incineration.

In general, LDPE carrier bags, which are the bags that are always available for purchase in Danish supermarkets, are the carriers providing the overall lowest environmental impacts even when not considering reuse.

This study looked at 16 different bags. It found that the minimum number of reusable bag reuses needed to equal the thin plastic shopping bag used just once was very high:

  • a Non-woven PP reusable bag needs to be reused 52 times;
  • a Woven PP reusable bag needs to be reused 45 times;
  • a Recycled PET reusable bag needs to be reused 84 times;
  • a Polyester PET reusable bag 35 times;
  • an Unbleached Paper bag 43 times, and
  • organic Cotton reusable bag an astounding 2,000 times.

U.K. Government LCA Environment Agency in Brief

Life cycle assessment of supermarket carrier bags: a review of the bags available in 2006

Click here for U.K. Study

 The study found that the conventional plastic shopping bag (HDPE) outperformed all alternatives, even reusable bags, on environmental performance. Conventional plastic bags have a much lower global warming potential. Heavier, sturdier reusable bags of all materials have a higher global warming potential.

Reusable bags are much more resource-intensive increasing their negative environmental impact. For example, the production of cotton with its heavy pesticide and water use has a negative impact on the environmental benefit of cotton bags. The consequence is that a cotton reusable bag has to be reused 131 times to be as good environmentally as a plastic shopping bag used just once.

  • Non-woven polypropylene bags would have to be reused 11 times to match environmentally the conventional thin bag used just once.
  • Paper bags would have to be reused three times to lower their global warming potential to match that of a conventional HDPE plastic shopping bag being used just once.

Amount of Primary Use of Alternatives to Match the HDPE Conventional Bag Environmental Performance With or Without Secondary Reuse of the HDPE Bag

 

Type of Carrier Bag HDPE Bag
(No Secondary Reuse)
HDPE Bag
(40.3% reused as kitchen catchers)
HDPE Bag
(100% reused as kitchen catchers)
HDPE Bag
(reused 3 times)
Plastic Bag 1 2 2 3
Paper Bag 3 4 7 9
LDPE Bag 4 5 9 12
Non-woven PP Bag 11 14 26 33
Cotton Bag 131 173 327 393

Extracts from Key Scientific Studies Comparing Paper to Other Bags

Quebec Government Life Cycle Assessment (LCA) 2018
Environmental and Economic Highlights of the Results of the Life Cycle Assessment of Shopping Bags

  • Page 64 - “Depending on the bag and the indicator and scenario, the paper bag is the least or lowest performing disposable bag with 4-28 times greater potential impacts than the conventional plastic bag.”

 

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Government of Denmark Ministry of Environmental Protection Agency (LCA) 2018
Life Cycle Assessment of grocery carrier bags

  • Page 18 - Paper bags need to be reused at least 43 times to equal the environmental impact of a plastic bag used just once. “Unbleached paper bags: Can be directly reused as waste bin bags for climate change, should be reused at least 43 times considering all other indicators. Finally, reuse as waste bin bag if possible, otherwise incinerate. Bleached paper bags: Reuse for grocery shopping at least 1 time for climate change, at least 43 times considering all indicators; reuse as waste bin bag if possible, otherwise incinerate.”
  • Page 78 - Paper and biopolymer carrier bags should be reused up to 40 times in order to provide for a similar environmental performance of the plastic bag. “LDPE carrier bags provided the absolute best environmental performance. With reuse as waste bin bag as the considered as disposal option, it suffices to reuse LDPE carrier bags one time before reusing them as waste bin bag… Paper and biopolymer carrier bags should be reused up to 40 times in order to provide for a similar environmental performance, mostly due to the impacts in the freshwater eutrophication impact category. …In order to provide a comparable performance to LDPE in all impact categories, the number of reuse times for cotton and composite bags increased to thousands of times."

Page 17

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U.K. Government LCA Environment Agency
Life cycle assessment of supermarket carrier bags

  • Page 7 – Executive Summary “The paper, LDPE, non-woven PP and cotton bags should be reused at least 3, 4, 11 and 131 times respectively to ensure that they have lower global warming potential than conventional HDPE carrier bags that are not reused. The number of times each would have to be reused when different proportions of conventional (HDPE) carrier bags are reused are shown in the table below.  Recycling or composting generally produce only a small reduction in global warming potential and abiotic depletion.“Type of carrier HDPE bag (No secondary reuse) HDPE bag (40.3% reused as bin liners) HDPE bag (100% reused as bin liners) HDPE bag (Used 3 times) Paper bag 3 4 7 9 LDPE bag 4 5 9 12 Non-woven PP bag 11 14 26 33 Cotton bag 131 173 327 393 The amount of primary use required to take reusable bags below the global warming potential of HDPE bags with and without secondary reuse.

  • Page 33 - 5.1 Global warming potential “The GWP (excluding primary reuse) for each lifecycle stage of each carrier bag is shown in figure 5.1. The cotton carrier bag is not shown in figure 5.1, because its GWP is more than ten times that of any other carrier bag. Figure 5.2 includes the cotton bag and shows the results based on the number of times each heavy duty bag would have to be used to reduce its GWP below that for the conventional HDPE bag. In round numbers these are: paper bag - 4 times, LDPE bag - 5 times, non-woven PP bag - 14 times and the cotton bag - 173 times.“

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Life Cycle Assessment of Grocery Bags in Common Use in the United States
Clemson University 2014 Robert Kimmel, Sc.D., Associate Professor of Packaging Science, Director, Clemson University Center for Flexible Packaging; KY d. Cooksey, Ph.D.; Cryovac Chair in Packaging Science and Allison Littman, Principal, Sustainable Ally, Lebanon TN

  • Page 87 - Global Warming Potential Plastic Retail Bags (PRBs) vs Paper – 1 Trip
    The Clemson study evaluated the environmental impact of each bag type based on use in a grocery trip to buy groceries. They found that on one trip, the use of paper grocery bags had significantly higher global warming potential than plastic shopping bags. See chart below.

  • Page 143 – Conclusion Paper vs Plastic Bag Environmental Impacts
    Figure 8.1 shows the comparison of Paper bags with PRBs on the basis of the number of “trips” required for each of the Paper bag types to be equivalent for the average of all of the environmental impact categories with PRBs containing 30% RC.
    Figure 8.1 shows that Paper (40% RC) bags have about 7.5 times the average environmental impacts compared to PRBs. Increasing the recycle content of Paper bags to 100% reduces this factor to about 4 times. Inclusion of secondary uses of PRBs and Paper bags in the models increases the average environmental impacts of Paper bags relative to PRBs by about 25% for both Paper bag recycle contents.
  • Page 96 – Global Warming Potential Plastic Bags versus Paper- Multiple Trips
    The Clemson study assumed that there would be an equally high reuse of paper bags for shopping. They evaluated the environmental impact of each bag type based on a range of possible reuses; trips to the grocery store to buy groceries. They looked at 3.1, 14.6 and 44 trips. In all cases, the plastic retail bag outperformed the paper bag in terms of a lower environmental impact and lower global warming potential. See chart below.

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Reason Foundation: How Green Is that Grocery Bag Ban? 2014
An Assessment of the Environmental and Economic Effects of Grocery Bag Bans and Taxes

  • A wide ranging overview of bag regulation in the US and impact on litter, resource consumption, environmental impact assessment of alternatives, impact of fees , taxes and bans on bag use, and an overview of LCAs and summary of comparative findings.
  • Pages 39-40

Table 3: Global Warming Potential of Various Bags Relative to HDPE

Boustead Ecobilan Nolan 2002 Nolan 2003 Intertek

UK

HDPE 1.0 1.0 1.0 1.0 1.0
LDPE - 2.6 6.1 4.5 3.3
NWPP - - 42.6 33.1 10.3
Paper 2.3 3.3 2.5 4.9 2.7
Biodegradable 4.9 1.5 1.4 0.4 0.8
Cloth - - 27.4 1.0 130.1

The differences noted above are location specific but single HDPE bags generally seen to have a lower environmental impact when used once. It clearly shows that paper has a higher global warming potential than plastic bags.

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The Sustainable Packaging Alliance Limited, RMIT University, Australia 2009
Environmental impacts of shopping bags Ref number: SPA1039WOW-01

  • Page 5 – Technical Summary “Overall the single use paper bag has the highest environmental impact as a result of pulp and paper production and the weight of material required per bag. The single use paper bag has the highest impact, or equal highest impact, for all categories except eutrophication. For most impact categories this result does not change if the bag is reused again (i.e. used for 2 shopping trips) but its relative ranking on solid waste does improve Technical Services Report significantly, from the equal highest impact (along with recycled HDPE and the PP reusable bag), to the second lowest impact.”

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Boustead Consulting & Associates for the Progressive Bag Alliance in the U.S.  2007
Life Cycle Assessment for Three Types of Grocery Bags

  • Page 3 – Executive Summary “More specifically, are grocery bags made other materials such as paper or compostable plastics really better for the environment than traditional plastic grocery bags? Currently, there is no conclusive evidence supporting the argument that banning single use plastic bags in favor of paper bags will reduce litter, decrease the country’s dependence on oil, or lower the quantities of solid waste going to landfills.”
  • Page 4 - The Boustead LCA provided an analysis of 3 types of grocery bags – recyclable plastic; compostable, biodegradable plastic; and recycled, recyclable paper. This LCA did not consider reusable bags.The study found that single-use plastic bags require less energy, fossil fuel and water than the equivalent amount of paper bags. Plastic bags generate less solid waste, acid rain, and GHG emissions than paper bags. The results showed that single use plastic bags made from polyethylene have many advantages over both compostable plastic bags made from EcoFlex and paper bags made with a minimum 30% recycled content.When compared to 30% recycled fiber paper bags, polyethylene grocery bags use energy in terms of fuels for manufacturing, less oil, and less potable water. In addition, polyethylene plastic grocery bags emit fewer global warming gases, less acid rain emissions, and less solid wastes. The same trend exists when comparing the typical polyethylene grocery bag to grocery bags made with compostable plastic resins— traditional plastic grocery bags use less energy in terms of fuels for manufacturing, less oil, and less potable water, and emit fewer global warming gases, less acid rain emissions, and less solid wastes.

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The ULS Summary Report 2008

  • Pages 3 and 4

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Scottish Government Environment Group Research Report 2005
Proposed Bag Levy – Extended Impact Assessment

  • Following the implementation of the Plastax on bags in Ireland, the Scottish government undertook an extensive two year consultation process with experts, industry, governments, and environmental groups.They did not do an original LCA but relied on the findings from the Carrefours LCA. Focus of the Scottish committee was primarily on behaviour change, unlike the Irish anti-litter focus. But the Scottish committee saw no evidence of litter reduction in Ireland. (Page 7)One of the key findings of this consultation was the recognition that bans and taxes can have unintended consequences that can hurt consumers, retailers, the environment.That bans and taxes can have the complete opposite effect from what is intended and generate more waste as consumers switch to other alternatives and have to purchase bin liners to manage waste.A 77% increase in paper bag use was one of the unintended consequences of the Irish Plastax (DEH) and there was an increase in plastic consumption as consumers switched to thicker bags equal to the reduction in plastic from the ban (1.4% 2003 to 2002). (UK Trade Information).

    The Scottish report showed that paper has a much higher environmental footprint than either plastic bags or reusables.

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Ecobilan–Carrefours Study eco bilan 2004
(Évaluation des impacts environnementaux des sacs de caisse, #300940BE8)
Evaluation of the environmental impacts of checkout bags

  • French global retailer, Carrefour, second to only Walmart in revenue, commissioned Price Waterhouse Coopers to do an LCA.  Peer reviewed by ADEME, the Agency for Environment and Energy Management.This LCA considered four types of carrier bags:
  1. HDPE bags made from virgin polymer (lightweight plastic carrier bags).
  2. Reusable LDPE bags made from virgin polymer (‘bags for life’).
  3. Paper bags made from recycled fibres.
  4. Biodegradable starch-based bags.
  • The Carrefour study takes for its base case an average waste management scenario for France, i.e. 45% of paper bags being recycled, 25% being incinerated and 26% landfilled. It did not look at plastic shopping bags with recycled content.The Carrefour study found that plastic is superior to paper on all environmental measures. A second case in which 65% of the plastic carryout sacks were reused as garbage bags (kitchen-catchers) displacing plastic bags bought for that specific purpose showed strong environmental advantages for `single-use’ plastic bags with another use for trash. 
Consumption of non-renewable energy Paper 2.2 times as much as plastic
Consumption of water Paper 4.7 times as much as plastic
Emissions of greenhouse gases Paper 3.1 times as much as plastic
Emission of acid gases Paper 2.7 times as much as plastic
Eutrophication Paper 18 times as much as plastic

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Franklin Associates (1990) for the Council of Solid Waste Solutions, U.S.
Institute for Lifecycle Environmental Assessment - MIT

  • The first major study to apply the LCA method to a comparison of carry bags in common use occurred in the U.S. The study was limited in its focus looking only at plastic versus paper bags.It showed that plastic bags have a lower environmental impact than paper bags. (Lewis et al, 2010)Plastic shopping bags use 20-40% less energy than paper bags and contribute 70-80% less solid waste. As well atmospheric emissions are 63-73% lower for plastic bags versus paper bags.2 plastic bags use 87% of the amount of energy used by 1 paper bag.Recycling has significant reduction impact on energy feedstock.