Wasted food’s heavy burden on climate

As obesity levels soar, cutting the vast amount of food we waste could have a major impact on reducing the effects of climate change, as well as alleviating world hunger.

By mid-century, an estimated one-tenth of all greenhouse gas emissions from agriculture could be traced back to food waste, according to new research.

Human use and misuse of land accounts for up to a quarter of all greenhouse gas emissions, and farming directly contributes at least 10 per cent, and perhaps twice as much. Yet roughly one-third of all food produced never makes it to the plate.

“Reducing food waste can contribute to fighting hunger, but to some extent also prevent climate impacts like more intense weather extremes and sea-level rise,” says lead author Ceren Hic, a scientific assistant at the Potsdam Institute for Climate Impact Research (PIK).

Her PIK colleague, Prajal Pradhan, a researcher in climate impacts and vulnerabilities, adds: “At the same time, agriculture is a major driver of climate change, accounting for more than 20 per cent of overall global greenhouse-gas emissions in 2010. Avoiding food loss and waste would therefore avoid unnecessary greenhouse gas emissions and help mitigate climate change.”

Weight increases

The news comes little more than a week after researchers at Imperial College London calculated that obesity levels among men have tripled, and among women, worldwide, have doubled to a new total of 640 million. More ominously, the average weight of humans has been increasing by 1.5 kilograms a decade since 1975. That means that humankind is growing not just in numbers, but in mass.

The two Imperial scientists and colleagues report in the journal Environmental Science and Technology that they analysed body type, food needs, food availability, economic development and greenhouse emissions for the past and the future, under a number of possible scenarios.

This kind of thinking ahead is not new, nor confined to any one country. Researchers worldwide have been thinking about the links between food security and climate, and the consequence of global dietary change on emissions has been a consistent calculation in the analysis of climate change. So much food is wasted that researchers have identified it as a potential energy source.

It is quite astounding that up to 14 per cent of overall agricultural emissions in 2050 could easily be avoided by better management of food utilisation and distribution.

Prajal Pradhan, researcher in climate impacts and vulnerabilities, Potsdam Institute for Climate Impact Research

What the Potsdam scientists found was that although global average food demand per person remained almost constant, food availability had increased rapidly in the last 50 years. And, Dr Pradhan says, this availability kept in step with development, which in turn suggested that rich countries consumed more food than was healthy, or simply wasted it.

Right now, humans discard 1.3 billion tonnes of food every year. In turn, that suggests that greenhouse gas emissions linked to food waste could soar from 500 million tonnes now to somewhere between 1.95 and 2.5 billion tonnes by 2050.

Agricultural emissions

Lifestyle changes and population growth – ever more people with seemingly ever larger appetites – could push emissions from agriculture alone to 18 billion tonnes of carbon dioxide equivalent by 2050.

“Thus, emissions related to discarded food are just the tip of the iceberg,” Dr Pradhan says. “However, it is quite astounding that up to 14 per cent of overall agricultural emissions in 2050 could easily be avoided by better management of food utilisation and distribution. Changing individual behaviour could be one key towards mitigating the climate crisis.”

As traditionally once-frugal communities develop, so the problems multiply.

Jürgen Kropp, a co-author of the report and head of climate change and development research at PIK, says: “As many emerging economies like China or India are projected to rapidly increase their food waste as a consequence of changing lifestyle, increasing welfare and dietary habits towards a larger share of animal-based products, this could over proportionally increase greenhouse gas emissions associated with food waste − at the same time undermining efforts for an ambitious climate protection.” 

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