Jo Khan* reports on the impact waste food is having on global warming and what can be done to manage it better…..
Last week the Intergovernmental Panel on Climate Change (IPCC) called for an overhaul of our global food production system to help fight climate change, and tackling food waste was one component of this.
In its special report on Climate Change and Land, the IPCC called for urgent change to farming practices, land use and dietary habits in order to maintain global food security, and to limit global warming to 1.5 degrees Celsius.
It found climate change is already affecting the whole food system — from drought reducing crop yields to extreme weather events damaging produce, food shortages are leading to increased poverty.
And while food waste can occur as a direct result of climate change, reducing it was also identified in the report as critical for lowering greenhouse gas emissions and improving food security.
So what’s the situation in Australia?
Food waste from paddock to plate
An estimated 7.3 million tonnes of food is wasted in Australia each year, according to the National Food Baseline report, which amounts to an average of nearly 300 kilograms per person.
A third of that waste occurs on the farm, a third through handling and manufacturing, and a third in households or at the consumer level, said Steven Lapidge, CEO of the Fight Food Waste Cooperative Research Centre.
“That’s probably a cost of around $18-20 billion each year,” Dr Lapidge said.
Although discussion about food waste often stirs up feelings of guilt around the old vegetables you threw out last week, what we throw out from our kitchens is only one part of the food waste problem.
“Where we really have trouble tracking food waste is in primary production and in food manufacturing,” Dr Lapidge said.
“A lot of the waste that occurs in primary production we just don’t hear about.”
Dr Lapidge said sugar cane was one example of production waste highlighted in the National Food Waste Baseline report.
“[Sugar cane] is being traded on global markets, and when prices in Brazil are low then it’s uneconomical to be growing cane here, so it gets left in the field,” he said.
“But it’s hard to tell how much waste there is because a lot of what’s left in the paddock isn’t recorded.”
In Melbourne, 60 per cent of food is wasted before it reaches the consumer, according to a 2016 study led by Rachel Carey from the University of Melbourne.
“On farms, for instance, if food doesn’t meet the strict specifications of the major retailers it is often wasted because it’s too expensive for farmers to pick and pack that food,” Dr Carey said.
“But food waste also occurs through manufacturing processes and with retailers.”
Her research has found Melbourne’s yearly food waste is responsible for 2.5 million tonnes of greenhouse gas emissions.
Methane emissions adding to climate change
Methane production from food waste sent to landfill is a particular problem.
“If the food waste [decomposed] in a field or on the street it would emit carbon dioxide,” said Pep Canadell, a CSIRO research scientist and executive director of the Global Carbon Project.
But when you chuck a wilted lettuce in your normal household bin, it ends up in landfill.
And because there’s no oxygen in the depths of a pile of landfill rubbish, the bacteria helping to decompose your lettuce release methane instead of carbon dioxide, Dr Canadell said.
Methane is 28 times more powerful as a greenhouse gas than carbon dioxide, over a 100 year period.
“The structure of the methane molecule is more powerful in capturing the heat coming from the Earth’s surface and re-emitting it,” he said.
But food waste is not just about the wilted lettuce and smelly meat in landfill, it’s also about the resources used to produce that in the first place, Dr Carey said.
“Food waste is also a waste of the land, water, energy and all the other inputs required to produce that food,” she said.
“The natural resources that are wasted when food isn’t eaten just puts more stress on the food system overall.”
She estimated that each Melburnian’s food waste footprint was equivalent to 41 hectares of land, or 113 litres of water a day — figures that are likely transferable to other Australian cities.
The total amount of land that is used globally to produce food that’s then wasted is estimated to be an area the size of China, Dr Lapidge said.
“That’s land that has been cleared, food that has been irrigated, animals that have been fed, nutrients put into the soil — all wasted when we don’t consume the food that has been grown for us to eat,” he said.
“So we could be using less land, and also using the land more effectively, rather than clearing more land which is what we are doing at the moment.
“And the clearing of new land removes the trees that we need to help reduce carbon dioxide in the atmosphere.
Cutting waste to stabilise food systems
Dr Carey said the fight against food waste must happen in all stages of food production, including at the major retailers.
“We need to see stakeholders through the food supply chain coming together to look at new innovative ways of reducing that waste, as well as helping consumers to reduce their household food waste,” she said.
Dr Carey said retailers could be relaxing the specifications that they have for produce, buying the whole crop from farmers and using different grades of that produce in different ways.
“I think there’s a lot that can be done to help farmers to reduce that loss.”
While she said it was good that some retailers were discounting “ugly food”, it was not clear what effect this was having on food waste.
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Vegetable farmer Anthony Houston said he had to grow some excess produce every week to make sure he didn’t run out of supply, but tried to ensure those extra veg weren’t wasted if they weren’t needed.
“If it’s a small amount of waste it’s not a problem because we plough it back into the farm and it’s good nutrients for the soil,” Mr Houston said.
“But sometimes, if we have packed up more than the market needs, we send it off to a food charity so that it can go to a good cause.”
He said climate change had necessitated new ideas for reducing food waste, including businesses that connect producers who have surplus produce with markets than can use it.
“I spend most of my life now fighting for climate [action], because not many people realise how bad it is or how fast it’s coming,” he said.
“Food waste is part of that, and it should not be going to landfill.”
* Jo Khan is a science journalist and broadcaster. She produces Off Track on Radio National and is also an online reporter for the RN Science unit. She tweets at @JoannaAKhan.
This article first appeared at www.abc.net.au
