The food being wasted yearly adds to the earth's carbon emission and means that large amounts of land is used to grow food that is not consumed.
Each night nearly 900-million people go to bed hungry, while a third of all the food that is produced gets thrown away.
The problem will grow more acute as population levels push towards 10-billion in the next few decades. To feed all of these extra people, global food production would need to increase by 60% by mid-century.
But the space to grow food is limited. The solution, championed by the Food and Agriculture Organisation of the United Nations is to save food and make food production and storage more efficient. By wasting less food, there is more to go around without breaking new ground.
The wasted food means that 1.4-billion hectares of land is being used to grow food that is not consumed – South Africa's total land mass covers around 120-million hectares. The global economic cost of the waste is $750-billion, or nearly R8-trillion.
José Graziano da Silva, the organisation's director general, said, "We simply cannot allow one-third of all food we produce to go to waste or be lost because of inappropriate practices."
The solution had to be all-encompassing, with changes at every link in the food chain doing its bit to stop waste, he said.
Reducing food waste
The organisation's report, Food Wastage Footprint: Impacts on Natural Resources, was released on September 11. It linked the waste of food with the impact it has on the environment. Each gram of grain produced requires water, arable land, air and everything else that costs natural resources.
Reducing food waste would go a long way when aiming to reach for the target of producing 60% more food required by 2050. "It seems clear that a reduction of food wastage at global, regional and national scales would have a substantial effect on natural and societal resources," it said.
The report is the first of its kind to link sustainability and the environment with food production.
Food production uses 70% of the world's fresh water, with the South African figure standing at around 65% of fresh water. As the 30th driest country in the world, this means any food that is wasted also wastes water.
In sub-Saharan Africa this is especially problematic because the water footprint is higher than in other regions. A hectare of maize grown in the region uses more water than a similar crop in Europe. Food wasted that has been grown here therefore costs the environment more.
The wasted food also comes at a cost to the environment, in the form of greenhouse gas emissions. According to the report, had the extra food not been grown, 3.3-billion tonnes of emissions could have been averted.
This makes food wastage the third highest emitter of gasses in the world, after China and the United States. South Africa emits around half a billion tonnes a year.
'Global food security'
"This food wastage represents a missed opportunity to improve global food security, but also to mitigate environmental impacts and resource use from food chains," said the report.
Achim Steiner, executive director of the United Nations Environment Programme, said preventing food waste was a big way to combat carbon emissions. "Food wastage is a major opportunity for economies to assist in a transition to a low carbon, resource efficient and inclusive green economy," he said.
His organisation was now running a campaign called "Think, Eat, Save – Reduce your footprint" to get others to prevent food waste.
Food wastage in South Africa is worse than the world average – half of its fresh produce is wasted. Research by the Council for Scientific and Industrial Research found that 3.6-billion kilogrammes of fruit and vegetables grown in the country are wasted. Most of this happens before the food gets to people's fridges.