Surpassing 2°C from Diet Alone

Decarbonization of the energy sector is the major focus of climate change mitigation. However, around a quarter of greenhouse gas emissions come from the production and consumption of food, of which only a fraction is from energy use. Evaluating the impact of future food consumption on global warming is therefore essential as we strive to stay below international temperature targets with a growing population. However, quantifying the contribution of food consumption to future warming is complicated by emissions of multiple greenhouse gases with varying radiative properties and atmospheric longevities. Studies typically report climate impacts of agriculture through simple metrics (e.g. carbon dioxide equivalence), but these metrics are unable to convey warming impacts of continuous emissions over time and require the selection of an arbitrary time horizon of interest. Based on a literature review of 113 studies, we resolve these challenges by developing a global food consumption emissions inventory by individual greenhouse gas—for 94 food items in 171 countries and for five population growth scenarios—and employ a reduced complexity climate model to evaluate temperature impacts. We find that if current dietary patterns are maintained, global food consumption alone will add about a degree Celsius to warming by the end of the century in comparison to today’s global temperatures, pushing us past the 2 °C threshold targeted by the Paris Agreement even if we decarbonize our energy sector. Sixty percent of the warming is driven by the emission of methane, and 75% from the consumption of animal products. However, we find that a quarter of anticipated warming can be avoided from improvements to production practices, and another 15% can be avoided by universal adoption of a “healthy” diet. Both demand- and supply-side interventions therefore become essential as we seek to feed a growing population while simultaneously curbing climate change.