From produce pop-up shops in Denmark to a law that forbids French supermarkets from tossing out unsold edibles, Europeans are getting serious about curbing food waste.

A third of all food produced worldwide ends up discarded unnecessarily - some 1.3 billion tons each year. That's a lot of grub rotting in landfills. And because rotting food is a major source of methane, a greenhouse gas that's more potent than carbon dioxide, it's a contributor to climate change that's often overlooked.

Now one of the most practical solutions to this problem - a mobile app that helps supermarkets and shoppers in the Netherlands save money and prevent food waste at the same time - is getting ready to expand to Germany, Belgium and the UK.

The idea for NoFoodWasted was hatched from a chicken, according to August de Vocht, the app's developer.

"It all started when I couldn't buy a whole chicken that was discounted because it was near its 'best before' [spoilage] date," said de Vocht, who barbecues every weekend at his home outside Amsterdam when he's responsible for preparing dinner for his wife and children.

RELATED: Food Waste? There's an App for That...

But because he promised his wife before he left for the supermarket that he wouldn't barbecue that weekend - and didn't know how to cook a whole chicken off the grill - he had to leave the chicken behind.

Afterwards, de Vocht kept thinking that if he'd just known about the discount earlier, he could have cleared grilling it with his wife. Then he wouldn't have had to leave the bird behind.

So de Vocht created the NoFoodWasted app, which allows shoppers to see discounted food items that are nearing their "best before" date at participating supermarkets throughout the Netherlands. Users can also input their shopping list to the app and receive push notifications on their smartphones when an item on their list is discounted.

NoFoodWasted is not limited to produce, meat and fish. Thanks to a type of Bluetooth device called beacons, the app can also help users identify canned or packaged items near spoilage by sending them a push message when they walk past these items in the grocery aisle. The beacons - which grocers affix to the bottom of the shelves where the items are located - notify shoppers by sending out signals to the NoFoodWasted users' phones. (The grocers connect the item to the beacon within the app).

There are now 20,000 daily users of the app since it launched in September 2014, expanding from 11 supermarkets to 175 over the past year.

RELATED: Are We Perilously Close to a Global Food Shock?

To date, NoFoodWasted users have saved $1.56 million (1.5 million euros) worth of food, according to de Vocht.

Supermarket franchise owners also benefit. De Vocht suggests that Dutch markets waste about 10,000 euros' worth of food a month, and his app has been saving them between 18 to 25 percent of the food they would have thrown away in the same time period - an amount worth 1,800 to 2,500 euros.

"It feels like there's a vibe out there where people are interested in improving their behavior on food waste," de Vocht remarked. "But we know that it still can be difficult for them because you have to change the way you shop for groceries."

To help individuals make this adjustment, NoFoodWasted is trying a few different approaches. One feature lets users know when items similar to those on their grocery lists are spoiling soon. A shopper might want broccoli, for example, but the app will alert them if a batch of cauliflower goes on sale. De Vocht has also hired a chef who is developing recipes for the app that feature discounted items that are available in large quantities nationwide.

"Behavior change is the most difficult thing that we have to do," he explained. "But our plan is to get people's patterns to change without them realizing that it's happening already."

WATCH: Why Do We Waste $1 Trillion of Food a Year?