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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 CH4 and N2O 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 CH4 and N2O 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 CO2 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.
Highlights
The global energy and food supply systems face substantial challenges over the 21st century, if global climate goals agreed to in the United Nations Framework Convention on Climate Change (UNFCCC) are to be met
The majority of Integrated AssessmentModels (IAMs) studies have focused on how the energy system needs to be transformed [1], but it is clear that reducing greenhouse gas (GHG) emissions from the food supply system is critical [2,3,4]
This paper aims to elucidate the effect of dietary changes on energy system transformation requirements under stringent climate targets and to highlight the indirect relationship between GHG
Summary
The global energy and food supply systems face substantial challenges over the 21st century, if global climate goals agreed to in the United Nations Framework Convention on Climate Change (UNFCCC) are to be met. Models (IAMs) show that negative emissions of CO2 may be required during the second half of this century if the global mean surface temperature is to be stabilized below 2 ◦ C above the pre-industrial level [1]. The majority of IAM studies have focused on how the energy system needs to be transformed [1], but it is clear that reducing greenhouse gas (GHG) emissions from the food supply system is critical [2,3,4]. Almost a quarter of global GHG emissions stem from agriculture and other land-use related activities [5]. Livestock account for more than half of these emissions [6]. While CO2 emissions from fossil sources dominate for the energy system, for the food-supply system, CO2
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