What is sustainable, anyway?

I'm standing in the supermarket. I'm in a hurry. I need tomatoes. There are juicy-looking organic ones from Turkey, wrapped in plastic I can't recycle and likely flown in with a side order of carbon dioxide. There are big, hard loose ones from Holland, possibly shipped (how can I tell?) but definitely conventionally grown and therefore bad for soils, water and creatures. There are fancy mini plum ones on the vine that come in recyclable plastic, but they're also conventionally grown – this time in Italy – but three times as expensive as the Dutch ones.

Which tomatoes are the most sustainable? I honestly have no idea. As far as I’m aware, there is no way for a salad lover to quantify the relative environmental trade-offs between recyclability, food miles and agricultural production methods in the eight minutes until the next bus arrives. Especially when (let’s be honest) what I’m really looking for are the ones that taste the best and don’t cost more than the bottle of wine I’ll be washing them down with.

Of course, the “most sustainable” tomatoes are the ones that will be bursting forth in my garden next month: fresh, zero food miles, organic, no plastic. Possibly knobbly, slightly green and with a tough skin due to the less-than-perfect watering regime – I’m busy! But it’s June, I don’t have a greenhouse, and I want tomatoes. So here I am, bewildered in the fresh produce aisle, getting in the way of my fellow shoppers, struggling to make what is from any rational perspective a very minor consumer decision with less than perfect information.

Destructive produce

In the end I go for the fancy mini plum ones. Why? Because they look the nicest, they’re grown in the EU, I don’t need that many and I can recycle the plastic. Least worst choice, I think. But I don’t know.

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Nobody walks into a supermarket with the express intention of filling their trolley with the most environmentally destructive produce they possibly can. Show me the human who ponders over their shopping list and thinks, yes! What I want today is a dinner that decimates bee populations, pumps loads of carbon dioxide into the environment, and comes wrapped in enough soft plastic to power the Poolbeg incinerator for a week.

But at the same time, there aren’t all that many of us who put sustainability high up in our decision-making process alongside price, flavour and nutrition. There are a multitude of entirely legitimate reasons for this: a tight budget, lack of awareness, lack of options... I could go on. But for consumers, one of the hardest to grapple with has to be the lack of information on what the most sustainable choice actually is.

Sustainability is inextricably linked to the idea of environmental limits, the planetary equivalent of vital signs: concentrations of atmospheric carbon dioxide, rates of biodiversity loss, freshwater and fertiliser use, etc. Exceed them, and things get unhealthy (for us more than the planet, but that’s another column). Which of these limits is the most important? How do they interact with each other? How can we measure them across a global supply chain in a way that makes sense to consumers? And even if we were to calculate it all, would any of the available options actually be environmentally healthy?

Information vacuum

Locked into an information vacuum, with no budget for overall environmental impact, we make do: buying for biodiversity? Go organic. For lower transport emissions? Keep it local. For lower agricultural emissions? Avoid meat. For less plastic? Get as much as you can loose, or at least, recyclable. For those of us trying to do less harm, these are the anecdotes we buy. But as a wise soul once said, the plural of anecdote is not data.

The idea that we should live within our means is hard to disagree with. I doubt I’ll find many people who are prepared to argue that we should push planetary systems beyond the point of no return, and damn the consequences. But while we may not be prepared to eat only the tomatoes we grow in our own gardens, most of us are willing to do the right thing where possible. Or, at the very least, not the worst thing. That willingness is the greatest asset we have for turning the tide on unsustainable consumption. It shouldn’t be so hard to act on.

Hannah Hamilton is a sustainability consultant specialising in biodiversity conservation and environmental communications