If you have a sad bunch of spinach wilting away in your fridge — you're not alone.

Food waste is a huge problem around the globe.

The United Nations estimates that about one-third of all food produced is lost or wasted. That's over a billion tons every year.

Cutting food waste is not just economically wise, it's also good for the planet. As reported in the New York Times, the Intergovernmental Panel on Climate Change found that "from 8 to 10% of greenhouse gas emissions are related to food lost during harvest and production or wasted by consumers," and that landfills with food waste emit methane, "a gas that is roughly 25 times more harmful than carbon dioxide."

One supermarket chain in Finland has an idea to address food waste. S-market has started holding "happy hours" at their stores. But instead of getting a cheap beer, shoppers get a discount on, say, a pound of shrimp or a pork tenderloin nearing its expiration date. S-market division manager Sari Ristaniemi joined The World from Helsinki, Finland, to talk about the concept.

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"A couple of years ago, we were really thinking, what should we do with our new ideas with food waste reduction? And we had a goal that we need to reduce our food waste by 15% by the end of 2020," Ristaniemi says. "We really wanted to find new ways and also to involve customers in this effort. So, we ended up fond of this idea of a 'happy hour' that would help our customers also to realize that it's OK to buy products which are close [to] their expiry date and they are still good to use. We tested the concept in some stores and it actually worked fine and it's now being used in all our stores throughout Finland."

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Marco Werman: Is this popular? Are you seeing lots of people flooding in at 9 a.m. just for that 60% off? Sari Ristaniemi: Yes, it's actually quite popular. You see a crowd gathering just before 9 a.m. and people go in early to find products. And then, when they hear the announcement in the loudspeakers, they go and buy the products from the cashier.

Here in the United States, I think a lot of food consumers believe that sell-by date is a hard and fast rule. Are attitudes changing there about how much longer you can eat food past that date? Yeah, we also tried that with our customers, that they would understand that the "best-before" [date] doesn't mean that you have to throw out the food. You can still use it and you can use your own senses to really try the food and [see] if you can still cook it.

" ... we also tried that with our customers, that they would understand that the 'best-before' doesn't mean that you have to throw out the food."

And you feel some people are changing their attitudes about that? Yeah, definitely there's a lot of discussion about this respect for food in Finland.

Have you been able to estimate how much food waste has been diverted through this program? Yes, we are measuring food based in all of our stores very closely. In some of the stores, the reduction has been as high as 10% after they have started the program. Yearly, in all our stores, we sell something like 70 million discounted products. It means in every store, every day, about 200 products. And part of that will be sold [30% off] during the daytime and during the happy hour, [60% off]. So, all in all, 200 products in all stores, every day.

We have to assume that in some parts of the world, there's enough food insecurity that very little goes to waste in some supermarkets. But from where you sit, in Helsinki, Finland, do you have an understanding of how big a problem this is, globally? We definitely have a good understanding of [it] and how consumers also understand [this] and respect our own efforts.

I'm curious, has this program changed your own personal consumption and eating habits? Definitely, yes. [With] this happy hour concept, I'm looking for the products on the shelves and I might find something that I haven't used before — [at] a very good price. So, I'm trying that. And also, of course, at home, I'm really concerned if I have something getting old. I don't like that at all. It has [also] changed ... my thinking of food and food quality and respect for food and food loss.

You don't like the act of throwing food away, I gather. No, not at all.

This interview has been edited and condensed for clarity.