the Importance of Food

“Food is the mother of all sustainability challenges… We can’t get below 2 degrees without major changes to this system.”

- Janet Ranganathan

Our food system contributes to climate change in two very important ways:

1. Deforestation (also called land use change), which triggers the release of massive amounts of CO2 that are locked in forests and other ecosystems.

2. Direct greenhouse gases emissions, including two very potent gases: methane and nitrous oxide.

The world population will grow from 7.2 billion today to an estimated 10 billion by 2050. Already, as the global population and global incomes rise, the demand for food, particularly meat and dairy, is growing rapidly. It’s projected that the agricultural sector will almost double in greenhouse gas emissions (from both deforestation and direct emissions) by 2050. This increase alone will make it incredibly hard to stay under 2C warming, even with drastic cuts in other sectors.

DEFORESTATION

By 2050, scientists estimate that an area twice the size of India will be deforested for agricultural purposes. Keeping forests and other ecosystems intact is crucial because they sequester carbon dioxide.

Raising livestock for food takes as much as 36 times more land (than, for example, a comparable amount of peas) because of the space required for grazing animals and the space required to produce feed for those animals.

Animal agriculture is a leading cause of deforestation worldwide and is responsible for 80% of the deforestation of the Amazon in recent years.

Methane

“Limiting warming to 1.5°C implies reaching net zero CO2 emissions globally around 2050 and concurrent deep reductions in emissions of non-CO2 forcers, particularly methane” (high confidence) - UN IPCC Special Report, 2018

Methane is 25-28 times more potent as a greenhouse gas than CO2

• 27% of methane produced is a result of livestock’s natural digestive processes (a process called enteric fermentation)

• Another 9% of methane comes from livestock manure management

• Another 16% of methane comes from landfills when organic matter (usually discarded food) decays without proper composting

highest impact Solutions

The challenge is this: to feed 10 billion people in 2050 without clearing more land for agriculture and while drastically reducing greenhouse gas emissions.

A landmark paper published in Nature in 2018 looked at combinations of changes that could be applied in our food system to keep us within budget for greenhouse gas emissions, including technological changes (increases in productivity through better crop and livestock management, etc.), dietary changes, and reductions in food waste.

They concluded that while a combination of changes are needed, the global shift to a plant-rich diet (see left) is essential and is the highest impact for bringing greenhouse gas emissions from the agricultural sector within budget for 2 degrees of warming or less.

This paper was part of a collection of research by the EAT-Lancet Commission, and its recommendations (now widely cited) became known as the Planetary Health Diet. 14 global cities such Tokyo, Paris, and Los Angeles, have all signed the C40 Good Food Cities Declaration to move their citizens to the Planetary Health Diet.

Read about why healthcare workers and others support San Francisco’s Good Food Purchasing Program

References

1. Ranganathan et. al. (Dec 2019). Creating a Sustainable Food Future. World Resources Institute.

2. Cattle Ranching in the Amazon Region. Yale School of Forestry & Environmental Studies.

3. Livestock’s Long Shadow: Environmental Issues and Options (2006). Food and Agricultural Organization of the United Nations.

4. IPCC Special Report: Global Warming of 1.5°C (2018).

5. Waite and Vennard (Oct 17, 2018). Without Changing Diets, Agriculture Alone Could Produce Enough Emissions to Surpass 1.5°C of Global Warming. World Resources Institute.

6. Springmann, Marco, et al. "Options for keeping the food system within environmental limits." Nature 562.7728 (2018): 519.