Shop Smart: Does buying seasonal make a difference?
And how much does distance actually matter?
One of the most common pieces of advice you’ll hear when you’re trying to eat more sustainably is to “eat seasonal”. But does this actually make a difference to the environmental impact of your food, or are the benefits overblown?
What “seasonal” really means
When we talk about eating seasonal foods, it’s important to understand what this actually means. There’s a tendency to equate “seasonal” with “local” because by eating seasonally we’re aiming to eat food that is grown within its natural growing season in the place that we live. However, the other (potentially more practical) way you can look at it is that “seasonal” means buying food that was grown in its natural season somewhere. In other words, food that is grown naturally outdoors without artificial heating or light.
Let’s look at a practical example. I live in Melbourne and I love bananas. This may shock you, but Melbourne doesn’t actually have a natural banana-growing season (I write on a 15-degree day in December). Almost all bananas in Australian supermarkets are Australian-grown (because of our very strict biosecurity laws), but more than 90% of them are grown in North Queensland where, thanks to the tropical weather, they can grow all year round.
Now, if we take the two definitions of seasonal above, there are two conclusions I can come to:
I should either feel free to eat bananas in Melbourne all year round (they’re always in season where they’re grown), or I should never eat bananas (there’s never a Melbourne banana season).
Hmm… that hasn’t really helped to work out if we should eat seasonal or not.
The two things that matter
If you want to make this simple and practical, all you need to think about are these two things:
How was it grown?
How did it get here?
Let’s start from the second point and work back. A big argument for buying seasonal produce is that it can be produced locally and so it travels only a short distance from the farm to the consumer. This is what we call food miles. Now, I’ve written about this before; food miles is a hot topic because it’s easy to understand and easy for companies to communicate to consumers. But, it actually doesn’t matter that much. At least not as much as you might think. The transport and storage of food typically only accounts for about 6% of its total greenhouse gas emissions. This obviously varies based on the type of food and how it’s transported but the factor that is pretty much always more important is how it was grown.
Again, let’s look at a practical example from a research article that comes up quite a bit when you start looking into sustainable food systems. There was a study that looked at the GHG emissions of tomatoes consumed in the UK under two scenarios - producing them in the UK in heated greenhouses, or producing them in-season in Spain then transporting to the UK. The results: the GHG emissions were far lower when the tomatoes were produced in Spain. The energy intensity of heating the greenhouses outweighed the transport emissions of moving the tomatoes.
There are other factors to consider here (two big ones being that: you can grow more tomatoes per square metre in a heated greenhouse than you can in a field, so the UK option takes up less land, and; transport distance is correlated with food waste, so there’s potentially more food wasted when moving them from Spain), but overall the takeaway is that how the food is produced is often more important than how far it was transported.
Putting it into practice
It can be hard (or even impossible) to know how the food on the supermarket shelf was produced, so here are three foods to focus on if you want to eat more seasonal produce that actually might have a lower environmental impact:
Berries - fruits that are soft and have short shelf lives are often air freighted out of season, which (despite what we said about distance not being that important) does actually have a massive environmental impact. Buy fresh berries in summer but the rest of the year, either try to cut back or buy the frozen ones (they’re not air freighted).
Tomatoes - these are in season through summer and autumn. Outside of that, they’re usually brought in from somewhere warmer or, more often than not, grown indoors in energy intensive systems.
Pre-packed fruit and veg - this has less to do with seasonality and more to do with general environmental impact. Pre-prepared and packaged foods normally involve more energy intensive processing and refrigeration, not to mention the plastic packaging!
So, buying seasonal isn’t the be-all and end-all of sustainable eating but it can be a good way to reduce your footprint (not to mention getting more diversity in your diet and saving a bit of money). Oh, and as for the bananas, I’ll keep enjoying them all year long.