Global food efficiency of climate change mitigation in agriculture

Concerns exist regarding potential trade-offs between climate change mitigation in agriculture and food security. Against this background, the Global Biosphere Management Model (GLOBIOM) is applied to a range of scenarios of mitigation of emissions from agriculture to assess the implications of climate mitigation for agricultural production, prices and food availability. The " food efficiency of mitigation " (FEM) is introduced as a tool to make statements about how to attain desired levels of agricultural mitigation in the most efficient manner in terms of food security. It is applied to a range of policy scenarios which contrast a climate policy regime with full global collaboration to scenarios of fragmented climate policies that grant exemptions to selected developing country groups. Results indicate increasing marginal costs of abatement in terms of food calories and suggest that agricultural mitigation is most food efficient in a policy regime with global collaboration. Exemptions from this regime cause food efficiency losses

Understanding the origin of Paris Agreement emission uncertainties

The UN Paris Agreement puts in place a legally binding mechanism to increase mitigation action over time. Countries put forward pledges called nationally determined contributions (NDC) whose impact is assessed in global stocktaking exercises. Subsequently, actions can then be strengthened in light of the Paris climate objective: Limiting global mean temperature increase to well below 2 °C and pursuing efforts to limit it further to 1.5 °C. However, pledged actions are currently described ambiguously and this complicates the global stocktaking exercise. Here, we systematically explore possible interpretations of NDC assumptions, and show that this results in estimated emissions for 2030 ranging from 47 to 63 GtCO2e yr-1. We show that this uncertainty has critical implications for the feasibility and cost to limit warming well below 2 °C and further to 1.5 °C. Countries are currently working towards clarifying the modalities of future NDCs. We identify salient avenues to reduce the overall uncertainty by about 10 percentage points through simple, technical clarifications regarding energy accounting rules. Remaining uncertainties depend to a large extent on politically valid choices about how NDCs are expressed, and therefore raise the importance of a thorough and robust process that keeps track of where emissions are heading over time

Energy Sector Adaptation in Response to Water Scarcity

Integrated assessment models (IAMs) have largely ignored the impacts of water scarcity on the energy sector and the related implications for climate change mitigation. However, significant water is required in the production of energy, including for thermoelectric power plant cooling, hydropower generation, irrigation for bioenergy, and the extraction and refining of liquid fuels. With a changing climate and expectations of increasing competition for water from the agricultural and municipal sectors, it is unclear whether sufficient water will be available where needed to support water-intensive energy technologies (e.g., thermoelectric generation) in the future. Thus, it is important that water use and water constraints are incorporated into IAMs to better understand energy sector adaptation to water scarcity. The MESSAGE model has recently been updated with the capability to quantify the water consumption and withdrawal requirements of the energy sector and now includes several cooling technologies for addressing water scarcity. These new capabilities have been used to quantify water consumption, water withdrawal, and thermal pollution associated with pre-existing climate change mitigation scenarios. The current study takes the next step by introducing water constraints into Shared Socioeconomic Pathway (SSP) scenarios to examine whether and how the energy sector can adapt to water scarcity. This study will provide insight into the following questions related to energy sector adaptation to water scarcity: How does the energy sector adapt to water scarcity in different regions? What are the costs associated with adaptation to water scarcity? How do adaptations to constraints on water withdrawal and consumption differ? Is climate mitigation limited under water scarcity (esp. with low deployment of wind/ solar)? How important are dry cooling and seawater cooling for addressing water scarcity and climate mitigation

Energy sector water use implications of a 2°C climate policy

Quantifying water implications of energy transitions is important for assessing long-term freshwater sustainability since large volumes of water are currently used throughout the energy sector. In this paper, we assess direct global energy sector water use and thermal water pollution across a broad range of energy system transformation pathways to assess water impacts of a 2 °C climate policy. A global integrated assessment model is equipped with the capabilities to account for the water impacts of technologies located throughout the energy supply chain. The model framework is applied across a broad range of 2 °C scenarios to highlight long-term water impact uncertainties over the 21st century. We find that water implications vary significantly across scenarios, and that adaptation in power plant cooling technology can considerably reduce global freshwater withdrawals and thermal pollution. Global freshwater consumption increases across all of the investigated 2 °C scenarios as a result of rapidly expanding electricity demand in developing regions and the prevalence of freshwater-cooled thermal power generation. Reducing energy demand emerges as a robust strategy for water conservation, and enables increased technological flexibility on the supply side to fulfill ambitious climate objectives. The results underscore the importance of an integrated approach when developing water, energy, and climate policy, especially in regions where rapid growth in both energy and water demands is anticipated

Energy Sector Adaptation in Response to Water Scarcity

Integrated assessment models (IAMs) have largely ignored the impacts of water scarcity on the energy sector and the related implications for climate change mitigation. However, significant water is required in the production of energy, including for thermoelectric power plant cooling, hydropower generation, irrigation for bioenergy, and the extraction and refining of liquid fuels. With a changing climate and expectations of increasing competition for water from the agricultural and municipal sectors, it is unclear whether sufficient water will be available where needed to support water-intensive energy technologies (e.g., thermoelectric generation) in the future. Thus, it is important that water use and water constraints are incorporated into IAMs to better understand energy sector adaptation to water scarcity. The MESSAGE model has recently been updated with the capability to quantify the water consumption and withdrawal requirements of the energy sector and now includes several cooling technologies for addressing water scarcity. These new capabilities have been used to quantify water consumption, water withdrawal, and thermal pollution associated with pre-existing climate change mitigation scenarios. The current study takes the next step by introducing water constraints into Shared Socioeconomic Pathway (SSP) scenarios to examine whether and how the energy sector can adapt to water scarcity. This study will provide insight into the following questions related to energy sector adaptation to water scarcity: How does the energy sector adapt to water scarcity in different regions? What are the costs associated with adaptation to water scarcity? How do adaptations to constraints on water withdrawal and consumption differ? Is climate mitigation limited under water scarcity (esp. with low deployment of wind/ solar)? How important are dry cooling and seawater cooling for addressing water scarcity and climate mitigation

Global food efficiency of climate change mitigation in agriculture

Concerns exist regarding potential trade-offs between climate change mitigation in agriculture and food security. Against this background, the Global Biosphere Management Model (GLOBIOM) is applied to a range of scenarios of mitigation of emissions from agriculture to assess the implications of climate mitigation for agricultural production, prices and food availability. The “food efficiency of mitigation” (FEM) is introduced as a tool to make statements about how to attain desired levels of agricultural mitigation in the most efficient manner in terms of food security. It is applied to a range of policy scenarios which contrast a climate policy regime with full global collaboration to scenarios of fragmented climate policies that grant exemptions to selected developing country groups. Results indicate increasing marginal costs of abatement in terms of food calories and suggest that agricultural mitigation is most food efficient in a policy regime with global collaboration. Exemptions from this regime cause food efficiency losse

Integration of energy system and computable general equilibrium models: An approach complementing energy and economic representations for mitigation analysis

Energy system and computable general equilibrium (CGE) models play vital roles in climate change mitigation studies. These models have advantages and disadvantages, and attempts have been made to integrate them. This study aimed to describe the method for integrating energy system and CGE models and demonstrate the new model that captures the strengths of both models. The method developed in this study ensured the detailed convergence of the energy system by exchanging the results iteratively. We demonstrated the model integration by adopting the method to MESSAGEix-GLOBIOM and AIM/Hub and estimating a mitigation scenario that limits the temperature rise to below 2 °C under the middle-of-the-road socioeconomic projection in Shared Socioeconomic Pathways. As a result of the integration, the index showing the difference between the two models proposed in this study decreased from 1.0 to 0.066. Therefore, we confirmed that these models estimated consistent scenarios. The diagnostic indicators showed that compared to its counterpart CGE model, the newly-developed model was characterized by a higher contribution of demand-side reductions, a lesser alteration in the primary energy supply composition, and lower abatement costs. Given the convergence and advantages of the integrated framework, the proposed method is useful for further application to mitigation studies

MESSAGEix workshop

The aim of the workshop is to help new users of the MESSAGEix modelling framework to get started with their modeling work. The main features of the “framework” are introduced, and the use cases of some features are shown. The user can learn how to build an energy model and how to represent some policy constraints in their energy scenarios. For information about the model, its structure, mathematical formulation and much more, please see the documentation at: https://docs.messageix.org. The different lectures contain the workshop slides, videos as well as tutorials for hands-on examples

Assessing the challenges of global long-term mitigation scenarios

The implications of global mitigation to achieve different long-term temperature goals (LTTGs) can be investigated in integrated assessment models (IAMs), which provide a large number of outputs including technology deployment levels, economic costs, carbon prices, annual rates of decarbonisation, degree of global net negative emissions required, as well as utilisation levels for fossil fuel plants. All of these factors can be considered in detail when judging the real-world feasibility of the mitigation scenarios produced by these models. This study presents a model inter-comparison of three widely used IAMs (TIAM, MESSAGE and WITCH) to analyse multiple mitigation scenarios exploring a range of LTTGs and a range of constraints, including delayed mitigation action, limited end-use electrification and delayed deployment of carbon capture technologies. The scenario outputs across the three models are examined and discussed and a matrix of the different factors concerning scenario feasibility is presented