How Do Dietary Choices Influence the Energy-System Cost of Stabilizing the Climate?

Abstract

Abstract:We investigate how different global dietary scenarios affect the constraints on, and costs of, transforming the energy system to reach a global temperature stabilization limit of 2 • C above the pre-industrial level. A global food and agriculture model, World Food Supply Model (WOFSUM), is used to create three dietary scenarios and to calculate the CH 4 and N 2 O emissions resulting from their respective food-supply chains. The diets are: (i) a reference diet based on current trends; (ii) a diet with high (reference-level) meat consumption, but without ruminant products (i.e., no beef, lamb, or dairy, only pork and poultry); and (iii) a vegan diet. The estimated CH 4 and N 2 O emissions from food production are fed into a coupled energy and climate-system optimization model to quantify the energy system implications of the different dietary scenarios, given a 2 • C target. The results indicate that a phase-out of ruminant products substantially increases the emission space for CO 2 by about 250 GtC which reduces the necessary pace of the energy system transition and cuts the net present value energy-system mitigation costs by 25%, for staying below 2 • C. Importantly, the additional cost savings with a vegan diet--beyond those achieved with a phase-out of ruminant products--are marginal (only one additional percentage point). This means that a general reduction of meat consumption is a far less effective strategy for meeting the 2 • C target than a reduction of beef and dairy consumption.

Environmental Impacts of Plant-Based Diets: How Does Organic Food Consumption Contribute to Environmental Sustainability?

“…Livestock results in GHG emissions such as nitrous oxide, carbon dioxide, and methane due to high-energy feed production, concentrating production and enteric fermentation of ruminants ( 3 ). However, impacts related to ruminant meat are higher when compared to monogastric animals because of methane emissions and the need for substantial livestock feed production needed ( 43 , 50 , 51 ). As consumers in the Q5 of the provegetarian score ate less meat, especially ruminant meat, compared to participants in the other quintiles, the difference in GHG emissions is further increased.…”

Development and validation of an individual sustainable diet index in the NutriNet-Santé study cohort

“…Indeed food exhibiting increased consumption in SDI Q5 compared to SDI Q1 in our study are those classified in the green class (low greenhouse gas emissions relate to food production and high SNRF), while those with a decrease are in the red class (high greenhouse gas emissions relate to food production and low SNRF). Moreover, meats from ruminants are related to more greenhouse gas emissions, energy and land consumption compared to poultry, pork and eggs (2,4,50) that is why the relative differences in these food group consumption between SDI Q1 and SDI Q5 are lower than for red meat. Finally, it is noteworthy that for some food groups, such as fish, egg and dairy products, no consensus has emerged certainly due to the differences in methodological and arbitrary choices concerning the objective function and constraints of linear programming with conflicting views on nutrition (adequate nutrient intake), environment (fish stock collapse or livestock environmental impacts) and contaminant exposition (in particular from fatty fish).…”

“…Indeed food exhibiting increased consumption in SDI Q5 compared to SDI Q1 in our study are those classified in the green class (low greenhouse gas emissions relate to food production and high SNRF), while those with a decrease are in the red class (high greenhouse gas emissions relate to food production and low SNRF). Moreover, meats from ruminants are related to more greenhouse gas emissions, energy and land consumption compared to poultry, pork and eggs ( 2 , 4 , 50 ) that is why the relative differences in these food group consumption between SDI Q1 and SDI Q5 are lower than for red meat.…”

Agricultural methane emissions and the potential formitigation

“…While some studies have suggested that future temperature targets could be achieved without major reductions in ruminant/agricultural methane emissions (102,103,104), Roe et al [95], synthesising previous top-down and bottom-up estimates of mitigation in agriculture propose a 25% reduction in agricultural non-CO 2 emissions by 2050, compared to business as usual, in their implementation roadmap for the land sector.…”