Feeding all the mouths in the world takes a toll on the planet, but people need to eat. Yet a new report by the United Nation's Food and Agriculture Organization (FAO) adds a seriously unsettling twist to the scenario. Every year about a third of all food produced for human consumption, around 1.3 billion tonnes, is wasted, along with the land, energy, water and chemicals needed to produce it and dispose of it.

In the Food Wastage Footprint report, experts at the FAO estimate that the carbon footprint of wasted food is equivalent to 3.3 billion tonnes of carbon dioxide annually, and that’s not accounting for greenhouse gas emissions from land use change. As such, the report notes, “food wastage ranks as the third top emitter after USA and China.”

The wasted food uses up around 250 cubic kilometers of water — equivalent to the annual water discharge of the Volga River, or three times the volume of Lake Geneva, the report notes. Produced but uneaten food also relies on almost 1.4 billion hectares of land, which means about 30 percent of the world’s agricultural land area is being exploited in vain.

While it is difficult to estimate impacts on biodiversity, the report explains, at a global level, “food wastage unduly compounds the negative externalities that monocropping and agriculture expansion into wild areas create on biodiversity loss, including mammals, birds, fish and amphibians.”

The FAO estimated the cost of the wasted food, excluding fish and seafood, was around $750 billion a year. (Pope Francis was on to something when he said that the culture of food waste is like stealing from the poor.)

In the first world, most of the waste comes from people buying too much and tossing what they can’t eat. The report urges consumers to serve smaller portions and make more use of leftovers. As well, it encourages businesses to donate surplus food to charities and develop alternatives to dumping organic waste in the landfill. In developing countries, the FAO cited inefficient farming and improper storage facilities as contributing to the problem.

The report notes that more efficient food use could contribute significantly to cutting greenhouse gases, and would provide important factors as well.

"Food wastage reduction would not only avoid pressure on scarce natural resources but also decrease the need to raise food production by 60 percent in order to meet the 2050 population demand," the report concludes.

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