Will 30p plastic bags end our habit for good – or is it time for more extreme measures?

It is a fairly hefty price hike, but it could pay off. Morrisons is increasing the price of its plastic bags to 30p, having already upped them to 20p earlier this year. The supermarket is trialling the charge in some of its Welsh stores, with money being “reinvested in plastic reduction programmes”, says a spokeswoman.

The 5p charge for single-use plastic bags that was introduced in Wales in 2011, then Northern Ireland and Scotland before England finally caught up in 2015, has been considered a success. The seven main supermarkets in England gave out 6bn fewer bags between in the first six months of the charge than in the corresponding period a year before. However, last year supermarkets sold 1.18bn of the thicker “bags for life”, prompting fears people were using these as single-use bags instead. The Environmental Investigation Agency has said bags for life should cost £1, rather than the 10p many supermarkets still charge.

But can raising prices have a positive environmental effect? Charges such as Morrison’s 30p bags “will hopefully encourage more people to save money and help the environment by taking their own bags with them”, says Tony Bosworth, a campaigner at Friends of the Earth. However, adds Lorraine Whitmarsh, a professor of environmental psychology at Cardiff University, there isn’t enough evidence to say that ramping up the price will create drastic change. It may even risk a backlash, she says. “I think the next step would be to think about charges for other packaging, for instance coffee cups and excess food packaging.”

However, Whitmarsh has found that nudging people to make more environmentally friendly choices through economic measures may not have a wider impact. “The more you rely on economic measures, the more it reinforces people’s economic motivations. They’re not doing it necessarily for environmental reasons and therefore you don’t get people to think about the environment more generally. It’s effective to change that particular behaviour, but it doesn’t change any other behaviours at all.”

Besides, says Bosworth, carrier bags “are just the tip of a vast plastic iceberg. Supermarkets must go much further to reduce unnecessary plastic. We also need the government to take tougher action, too – including backing a proposed new law to phase out the use of all but the most essential plastic.” Thirty pence already seems a small price to pay.