Does diet matter for climate change, or just fossil fuels?

The objection

“Climate change is fossil fuels and a hundred corporations. Guilt-tripping me about dinner is a distraction.”

The answer

The anger at the fossil fuel industry is well placed. Cutting fossil fuel emissions is essential to meeting the Paris climate goals [1], and the industry has leaned on the idea that the problem lies with consumers. In a peer-reviewed analysis of 180 ExxonMobil climate communications, Supran and Oreskes (2021) found the company used talk of consumer energy “demand” in ways that individualise responsibility, a pattern they compare with the tobacco industry shifting responsibility onto its customers [2]. Holding those companies to account is right, but by itself it does nothing about the emissions from farming and land use, which make up most of food’s share.

How much of the world’s emissions come from food?

Food systems produce about a third of the world’s greenhouse gas emissions. The IPCC’s most recent report on cutting emissions (2022) put them at 17 billion tonnes of CO2-equivalent in 2018, 31% of all human-caused emissions with a range of 23 to 42%, up from 14 billion tonnes in 1990 [3]. Other estimates fall inside that range: 26% from Poore and Nemecek’s data (2018), and 34% for 2015 from Crippa and colleagues (2021), who counted all deforestation against agriculture where Poore and Nemecek counted 60% of it against food [4][5]. More than half of food’s emissions come from animal products. In Our World in Data’s breakdown of Poore and Nemecek’s figures (2019), livestock and fisheries produce 31% of food’s emissions, land used for livestock 16% and crops grown for animal feed 6% [6].

Do 100 companies cause 71% of emissions?

The 71% figure is real, but it counts only industrial emissions and leaves most of food’s footprint out. It comes from a 2017 report by the non-profit CDP with the Climate Accountability Institute, which traced 71% of global industrial greenhouse gas emissions since 1988 to 100 fossil fuel producers [7]. “Industrial” excludes sources such as carbon dioxide from land-use change and methane from agriculture, and 90% of the emissions in the database come from burning the coal, oil and gas those producers sold [7]. By the IPCC’s count, farming and land use produced about 10 of food’s 17 billion tonnes in 2018, some 19% of all human-caused emissions [3]. The food system’s energy use, waste and industrial processes made up the other 12%, with energy the largest part at 3.9 billion tonnes [3]. Cutting fossil fuels would shrink that energy part, and the 71% is a strong case for regulating the companies that sell them; it says nothing about the farming and land use behind most of food’s emissions.

Could cutting fossil fuels alone meet the climate targets?

Cutting fossil fuels alone would not hold warming to 1.5°C, because the food system on its current course would breach that limit by itself. Clark and colleagues (2020) found that even if fossil fuel emissions were halted immediately, current trends in global food systems would prevent the 1.5°C target being met and, by the end of the century, threaten 2°C [1]. Writing for Oxford’s LEAP programme in 2020, the lead author, Michael Clark, said food emissions alone would take the world past 1.5°C of warming by 2065, and to 2°C shortly after 2100 [8]. The changes the team looked at included healthier, mainly plant-based diets, less food loss and waste, higher crop yields and more efficient production; with fossil fuel emissions stopped, any one of them could meet 2°C, but 1.5°C would need all of them [8].

Is changing your diet a distraction from changing the system?

Changing your diet works alongside changing the system, and the IPCC (2022) says both supply-side and demand-side measures are important to reduce the greenhouse gas intensity of food systems [3]. It found, with robust evidence and high agreement, that diets high in plant protein and low in meat and dairy are associated with lower emissions [3]. The same chapter, citing the IPCC’s 2019 report on land, gives demand-side measures such as dietary change a technical potential of 0.7 to 8.0 billion tonnes of CO2-equivalent a year by 2050, comparable to the 2.3 to 9.6 billion from supply-side options [3]. Action, it concludes, has to reach consumers as well as producers. That potential is spread across whole populations, and what one person’s switch changes depends on how far production follows demand. The fossil fuel industry’s “demand” argument, as Supran and Oreskes describe it, has been used to oppose litigation, regulation and activism [2]; cutting your own demand for animal products rules out none of those.