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Is it time for a levy or ban on plastic bags?

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A plastic straw is slowly and painfully extracted from a sea turtle’s nostril. The opened stomach of a dead albatross reveals a smorgasbord of plastic bottle tops, plastic fishing line and other plastic detritus. A plastic shopping bag dangles from the throat of a seagull. A young seal wears a tangled scarf of plastic around its neck.

There’s no shortage of online photographic and video evidence of the harm that plastic waste is causing to marine life. It’s been estimated that between five and 13 million tonnes of it winds up in the oceans every year. Scientists have predicted that by 2025, there will be one tonne of plastic for every three tonnes of fish in the sea, and by 2050, the ratio could be 1:1.

Birds and marine animals wind up eating it, suffocating on it and getting tangled in it. It’s been estimated that 90% of seabirds and half of all turtles have ingested plastic. It also breaks down slowly into micro-particles and enters the food chain.

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Plastic is so deeply integrated into modern life that we barely notice it – unless you’ve ever attempted to eradicate it from your life. Try buying a bag of carrots, a loaf of bread, a set of bedsheets or a packet of batteries without also taking home yet another clutch of single-use plastic wrapping.

But few items of plastic are as widespread as shopping bags. As one commentator put it, the single-use supermarket bag is a “pervasive icon of convenience”, a symbol of modern society’s emphasis on simplicity and ease.

It’s estimated that humans use about a million of them every minute, and up to a trillion are discarded every year. A few get a second life as kitchen bin liners, dog poo containers or muddy-football-boot carriers. But most accumulate in a drawer or cupboard until there is room for no more, at which point they are dispatched with the garbage collection to landfill, from where they are liable to dance about on the wind and end up snagged on bushes and fences or floating in streams towards the sea. Despite efforts to promote multi-use cloth bags, it’s easy to forget them when dashing into the supermarket – it would be great to have reminder signs in car parks.

As much as they are an icon of convenience, plastic shopping bags are an easy-to-grasp proxy for today’s unsustainable exploitation of resources that is pushing the biosphere towards crisis.

Slashing consumption of a product that is made from fossil fuels, litters the environment and endangers marine life is such a low-hanging fruit that it’s no surprise there is widespread public support for policy action. According to one survey, two-thirds of people would support a levy on shopping bags if the money went to charity. Half the country’s mayors also want a levy. Greenpeace launched a campaign this week calling for a ban on single-use bags.

Associate Environment Minister Scott Simpson has set up a working group looking at ways to reduce plastic-bag consumption but opposes a ban, which he says would cause “pushback”.

Although action to reduce plastic bags is a no-brainer, policy needs to be well designed to avoid unintended consequences. There’s little point in driving consumers away from single-use bags if they end up using other types that have a higher environmental footprint. Life-cycle analysis has shown, for instance, that paper bags have to be used four times to have less environmental impact than a standard plastic supermarket bag, and a cotton bag has to be used more than 130 times to create a net environmental gain.

And although shoppers may feel virtuous when toting their multi-use cloth bags, in reality their action is trivial if they drive to the supermarket in gas-guzzling SUVs or fly off for weekend getaways in Melbourne or Sydney.

Plastic-bag levies and bans have resulted in lower consumption in many other countries, and there’s a strong case for New Zealand to follow suit. But these bags are just one contributor to the ocean of plastic waste that’s damaging marine life, and plastic is just one part of a much wider system of unsustainable resource use. Limiting plastic-bag consumption is just one action among many needed to minimise waste – but it’s an important step in the right direction.

This article was first published in the August 12, 2017 issue of the New Zealand Listener.