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Reducing single-use plastic waste

Plastic in ocean

Our research underpinned the UK Government’s policy change of charging for single-use plastic bags and disposable coffee cups.

Reducing single-use plastic waste is a problem that requires broad public behavioural change supported by effective legislation.

Research led by Professor Wouter Poortinga of the School of Psychology and Welsh School of Architecture quantified the impact and public acceptance of single-use plastic bag and disposable coffee cup charges. It was the first to identify both increasing public support for charges as well as increased public appetite for further, related policy changes.

This research underpinned Welsh, Scottish and UK Government policy changes, which led to charging for single-use plastic bags and disposable coffee cups. It also directly prevented 9.4 million disposable coffee cups going to landfill from catering companies and was highly influential with regard to national debates around single-use plastics and packaging.

Key research outcomes

  • Underpinned UK Government’s policy change of charging for single-use plastics
  • Prevented 9.4 million disposable coffee cups going to landfill
  • Highly influential with regard to national debates around single-use plastics

Underpinning research

Plastic waste often does not decompose and can last centuries in landfill or end up as litter in the natural environment. This, in turn, pollutes soils, rivers and oceans, harming animals living in these habitats. Our research on this significant societal challenge involved a series of interlinked research projects on carrier bag and coffee cup charging.

Single-use plastic bags

In 2011, the research team received funding from the Welsh Government to evaluate the introduction of the Welsh carrier bag charge. This research was the first controlled field study exploring behavioural and attitudinal impacts of a carrier bag charge. The results showed that the charge substantially reduced the use of plastic bags and that the policy became more popular after it was introduced.

In 2015, the law was changed in England, requiring shops to charge 5p for all single-use plastic carrier bags. Through ESRC funding, the research team was able to investigate the behavioural and attitudinal impacts to the English plastic bag charge, and also to use Understanding Society data to examine the long-term impacts of the Welsh carrier bag charge.

A key finding was evidence of ‘policy spill-over’ where people did not only become more supportive of the bag charge after it was introduced, they also became more supportive of other charges to reduce plastic waste.

Disposable coffee cups

The outcomes of the plastic bags project led to a collaboration between Cardiff University and Bewley’s - one of Ireland’s leading tea and coffee companies. This study was carried out at twelve sites across the UK managed by Bartlett Mitchell, a contract caterer, and four UK universities between September and December 2016.

The research found that the use of single-use coffee cups could be reduced annually by 50 to 300 million through introducing easily implementable measures, such as cafes offering financial incentives and re-usable alternatives. A key finding was that a 25p charge on disposable cups increased the use of reusable cups, but a discount on reusable cups does not.

"This research not only showed that modest charges on plastic bags and disposable coffee cups led to substantial behavioural changes, but also that the charges act as a catalyst to wider awareness of the detrimental impacts of plastic waste and pollution, leading to increased public support for further policy actions."
Professor Wouter Poortinga - Research lead

Making a difference

This research influenced policy, directly reduced the waste of UK and Irish-based coffee and catering companies, and influenced public debate around environmental charging.

Influencing policy

The research was instrumental in informing changes in legislation -  some of the policies and enquiries it influenced were:

  • Environmental Audit Committee (EAC) Plastic Bag Enquiry
  • Wales Environment Act 2016
  • Environmental Audit Committee (EAC) Disposable Packaging: Coffee Cups and Plastic Bottles Enquiry: In October 2017
  • Scottish Circular Economy Bill

Environmental changes

This collaborative research with Bewley’s indicated a series of simple changes that could be implemented by coffee chains to reduce use of disposable cups. As a result, Bewley’s confirmed:

  • A 30% reduction in sales of disposable cups since the research was completed in 2016, preventing approximately 9.4 million cups per annum from going to landfill
  • One company, Bartlett Mitchell, prevented 500,000 disposable cups being used
  • Data provided by the four universities that instituted the disposable cup tax confirmed a further 250,000 cups had been saved from landfill in one year alone.

Raising public awareness and driving industry response

  • The research results were widely reported in national and international media, with over 200 pieces reaching 54% of UK adults between 29 September and 31 October 2016
  • 90% of shoppers in England now use their own carrier bags, up from 70% before the levy was introduced
  • UK Google Searches for “reusable coffee cups” immediately rose to approximately 10-fold of pre-publication levels, and since then have maintained a 4-fold increase for more than 2 years.

Press coverage

Both the single-use plastics and coffee cup elements of the research generated significant media interest.

Guardian News

Reusable incentives could slash disposable coffee cup waste

Free reusables, 25p charge on disposables and green slogans in cafes could cut some of 2.5bn cups thrown away each year.

bbc News

Plastic bag charge: Could fee be applied to other packaging?

A 5p charge for plastic bags in large stores was introduced a year ago, and research suggests it's had positive environmental effects with usage radically reduced.

Mail online News

Charging for disposable coffee cups could help cut the number thrown away by 300million a year

Academics at Cardiff University say a charge would reduce waste and litter.

Meet the team

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