Last time you went to the supermarket how did you carry your shopping home ?

Your own fabric bags, durable PVC bags-for-life from the checkout, or did you take the free disposable plastic bags ? Perhaps you’re so image-confident that you used an oldschool wheeled shopping trolley, like grandmother used to – perhaps not !

This one really should be straightforward shouldn’t it?

We’re all aware of the issues: disposable plastic bags take energy to manufacture and transport, they cause litter, and many end-up as oceanic debris or lasting for hundreds of years in landfills. Reusing our own bags costs us nothing and causes us hardly any inconvenience. We’re even reminded and encouraged by the supermarkets, nudging us to do the right thing, by offering us loyalty points for reusing our bags.

So how are we doing ?

Not that well it turns out – around 10 billion lightweight disposable bags are handed free to UK shoppers every year. That’s about 200 each!

Obviously the ‘problem of carrier bags’ is a bit more wicked than we thought.

Perhaps it shouldn’t be a surprise that we find changing our habits quite a struggle. We’re able to go shopping 24/7, and as a result it’s just not that big a deal any more. We drop-in to the supermarket for ‘top-up-shops’ more frequently than we ever used to – no planning, no lists.

Having our own bags with us when we go requires preparedness, and the reality is that all too often we’ve left them at home because we were too tired/busy to put them straight back in the car after the last time. We’re frequently rushing – either to get home, get to work, or get somewhere else, and have usually got a lot more on our minds than remembering to take our bags. We seem to have collective amnesia.

Having forgotten the bags we then may experience something psychologists call cognitive dissonance.

We know we should reuse our bags, but have forgotten to, so to stop feeling bad and guilty we create mental excuses to justify ourselves – our time is too valuable to worry about something as trivial as carrier bags, besides we do plenty of other things for the environment, and it’s really an issue for the supermarkets or the government to sort out, and anyway what difference will a couple of carrier bags really make – we also promise ourselves we’ll reuse these bags next time.

Not using plastic bags might not save the world alone, but it’s possibly more important than you think, not just because of the energy footprint and plastic pollution, it’s also important for another reason. The problem of plastic bags is representative of a lot of other mass behaviour issues, from transport to food, where similar factors apply – relationships between convenience, cost, personal choice, responsibility, what everyone else is doing and how well we understand and accept the facts all play a part in determining our collective behaviour. Can good motives and gentle policy nudges make us all ‘do the right thing’, or is something else required ?

Breaking bad habits, like constantly forgetting to reuse bags, is hard – but we can make things easier for ourselves if rather than focussing only on the things we want to stop doing, we try to focus more on the things we want to start doing. It’s hard to say NO to something, until we’ve already said YES to something we want more.

If we cultivate a habit of returning our empty bags to the car after we unpack them, we’d have more chance of breaking our bad habit of taking new bags at the checkout.

So problem solved ?

Well, yes and no . . . how damaging are plastic bags anyway ?

Clearly manufacturing and transporting 10 billion bags a year in the UK alone, then giving them away free so they can be used once and then almost immediately thrown away  - causing local litter, filling landfills, and some ending up in the worlds oceans, isn’t going to win any environmental awards. The question is what are the alternatives ?

In February the UK Environment Agency published a report on the Life Cycle Assessment of Supermarket Carrier Bags. It suggests that a typical cotton ‘bag-for-life’ must be reused 171 times before it has a lower carbon footprint than a typical HDPE disposable bag, assuming the disposable bag is used once and then disposed of as a bin-liner for kitchen waste going to landfill. Crucially the report also states that cotton bags-for-life are, on average, actually only reused 51 times before being thrown away – making disposable HDPE bags much more environmentally friendly, at least in terms of carbon footprint !

Needless to say this has proved very controversial. In fact the report was quickly removed from the Environment Agency website, but with a bit of snooping around you can find copies elsewhere on the web if you’re interested – try here.

So things are more complex than they first appeared, and there are strong opinions on both sides – the same can be said of many other environmental issues. Sometimes we need to try to see things more simply.

It’s easy to get distracted by complexity and uncertainty, but unless we make a living from research or devising policy, the question that really matters is  - what should my own personal response be?

In the case of plastic bags, I’d suggest we simply keep reusing whatever bags we already have whenever we go shopping, keep doing so for as long as possible, and when we do eventually have to get new bags, choose them carefully based largely on durability.

In my own case I’ll also try to make sure I return my used bags to the car !

I’ll let Kermit have the last word.

Photo by Iragerich