One third of all food produced in the world gets wasted, amounting to a loss of $750 billion to producers each year, according to a report released on 11 September by the Rome-based Food and Agriculture Organization (FAO).

The United Nations agency said that around 1.3 billion tonnes of food is wasted annually, without taking into account the fish and seafood sectors. Titled the Food Wastage Footprint: Impacts on Natural Resources, the report is the first to analyse the impacts of global food wastage from an environmental perspective, examining the consequences of food wastage on the world's climate, water and land use, and biodiversity.

It found that food waste adds 3.3 billion tons of greenhouse gases to the planet's atmosphere, causes unnecessary carbon emissions and extra water consumption, and reduces biodiversity as an increasing amount of land is developed agriculturally. "We simply cannot allow one third of all the food we produce to go to waste or be lost because of inappropriate practices, when 870 million people go hungry every day," said FAO director general José Graziano da Silva during the report's presentation. "All of us – farmers and fishers; food processors and supermarkets; local and national governments; individual consumers – must make changes at every link of the human food chain to prevent food wastage from happening in the first place, and re-use or recycle it when we can't."

The report stated that 54 per cent of global food wastage happens in the early stages such as production and storage, while the rest occurs during processing, distribution and consumption. The report said that the later a food product is lost, the greater the environmental consequences. In addition to the price paid by the consumer, factors such as the costs incurred during processing, transport, storage and cooking must be taken into consideration.

The study revealed that food in developing countries is wasted mainly due to poor harvesting techniques, while in high-income areas the primary cause of waste is careless consumer behaviour, such as over-purchasing and overreacting to best-before-dates.

FAO said that another wastage factor in affluent countries is that quality and aesthetic standards lead retailers to reject large amounts of perfectly edible food. The most significant cases of waste relate to cereals in Asia, and meat in affluent regions and in Latin America. FAO said measures to combat waste included a better balance between food production and demand, sourcing secondary markets for surplus food and, in some cases, donating it to vulnerable members of society.

Where re-use is not possible – the report said – recycling and recovery should be pursued to stop uneaten food rotting in landfills and producing harmful greenhouse gases.

FAO's campaign to combat food losses has reveived the support of Pope Francis, who dedicated his weekly papal audience on 5 June to the UN World Environment Day. The pontiff said “Consumerism has led us to become used to an excess and daily waste of food, to which, at times we are no longer able to give a just value. Throwing away food is like stealing from the table of the poor and the hungry.”