Paper vs plastic bags: which is actually better for the climate?

Here’s the uncomfortable answer life-cycle studies keep giving: on greenhouse gases alone, a thin plastic bag often beats a paper one, because paper takes more energy and water to produce. But that’s the wrong question — the thing that actually matters is how many times you reuse whatever you carry.

What the life-cycle studies find

The much-cited Danish EPA 2018 bag study and the UK Environment Agency’s earlier work compared bags across their whole life. Roughly, to match the climate impact of one lightweight plastic bag, you’d need to reuse:

That last row surprises people: a cotton tote has such a high production footprint that, on climate, it has to be used a very large number of times to come out ahead. Buying a new tote at every checkout is the worst of both worlds.

But climate isn’t the only axis

Plastic wins on production carbon and loses badly on litter and ocean persistence — it doesn’t biodegrade and fragments into microplastics. Paper biodegrades but costs more carbon up front. So “which is better” genuinely depends on whether you’re worried about emissions or pollution.

The honest framing — the question is reuse

The single rule that resolves it: use what you already have, as many times as possible. A plastic bag reused ten times as a bin liner beats a cotton tote bought and forgotten. The greenest bag is almost never a new one of any material — it’s the one already in your cupboard. Like recycling, bag choice is a small, downstream lever; don’t let it crowd out the decisions that move tonnes.

Sources: Danish Environmental Protection Agency (2018), life-cycle assessment of grocery carrier bags; UK Environment Agency (2011) life-cycle assessment of supermarket carrier bags.