The Energy Journal

This study gives a synthesis of a model comparison assessing the technological feasibility and economic consequences of achieving greenhouse gas concentration targets that are sufficiently low to keep the increase in global mean temperature below 2 degrees Celsius above pre-industrial levels. All five global energy-environment-economy models show that achieving low greenhouse gas concentration targets is technically feasible and economically viable. The ranking of the importance of individual technology options is robust across models. For the lowest stabilization target (400 ppm CO2 eq), the use of bio-energy in combination with CCS plays a crucial role, and biomass potential dominates the cost of reaching this target. Without CCS or the considerable extension of renewables the 400 ppm CO2 eq target is not achievable. Across the models, estimated aggregate costs up to 2100 are below 0.8% global GDP for 550 ppm CO2 eq stabilization and below 2.5% for the 400 ppm CO2 eq pathway.

This paper presents a long-term assessment of the worldwide energy system in scenarios ranging from a baseline to a very low greenhouse gas stabilization, using the energy model POLES. Despite improved energy efficiency, the baseline scenario would lead to a doubling in energy consumption by 2050 increasing further thereafter. CO2 emissions would continue rising, driven by the coal consumed in the power production which roughly follows the GDP growth; the scarcity of oil resources would trigger the development of alternative vehicles. Conversely, a 400 ppm CO2 eq stabilization case would lead to drastic changes in supply (renewables - biomass), transformation (carbon capture and storage) and demand (low energy technologies). It transpires that the contribution to the reduction effort of low stabilization compared to a baseline scenario would be similar for final consumption (36% efficiency and 10% fuel mix) and for the power sector (25% renewables, 25% CCS, 4% nuclear). In addition this low emission scenario would alleviate the tensions on fossil energy markets.

This paper investigates long-term transitions of the global energy system compatible with realizing low stabilization climate targets, using an enhanced MERGE model. The results indicate that stringent mitigation targets can be met under many technology scenarios, but major technological change is needed, highlighting important roles for R&D and learning-by-doing. The analysis explores the impact of limiting the set of available technology options (to account for technical uncertainties and issues of public acceptance) and identifies important influences on energy system development and economic costs under low stabilization. Biomass availability is seen to have a major influence on the characteristics of the energy system. Carbon capture and storage technologies also prove to be potentially critical for both electricity and fuel synthesis, particularly when combined with biomass to produce net negative emissions. Additionally, the availability of fast breeders provides a competitive zero-emissions option. Energy efficiency and large-scale application of renewables are also critical to realising low stabilization scenarios.

Within this paper, we explore the technical and economic feasibility of very low stabilization of atmospheric GHG concentration based on the hybrid model REMIND-R. The Fourth Assessment Report of the IPCC and the scientific literature have analyzed some low stabilization scenarios but with as yet little attention being given to the regional distribution of the global mitigation costs. Our study helps to fill this gap. While we examine how technological development and international trade affect mitigation costs, this paper is novel in addressing the interaction between both. Simulation results show for instance that reduced revenues from fossil fuel exports in a low stabilization scenario tend to increase mitigation costs borne by the exporting countries, but this impact varies with the technology options available. Furthermore it turns out that the use of biomass in combination with carbon capturing and sequestration is key in order to achieve ambitious CO2 reduction targets. Regions with high biomass potential can clearly benefit from the implementation of low stabilization scenarios due to advantages on the carbon market. This may even hold if a reduced biomass potential is assumed.

The literature on climate stabilization modeling largely refers to either energy-system or inter-temporal computable general equilibrium/optimal growth models. We contribute with a different perspective by deploying a large-scale macro-econometric hybrid simulation model of the global energy-environment-economy (E3MG) adopting a “New Economics” approach. We use E3MG to assess the implications of a low-stabilization target of 400ppm CO2 equivalent by 2100, assuming both fiscal instruments and regulation. We assert that if governments adopt more stringent climate targets for rapid and early decarbonization, such actions are likely to induce more investment and increased technological change in favor of low-carbon alternatives. Contrary to the conventional view on the economics of climate change, a transition towards a low-carbon society as modeled with E3MG leads to macroeconomic benefits, especially in conditions of unemployment, with GDP slightly above a reference scenario, depending on use of tax or auction revenues. In addition, more stringent action can lead to higher benefits.

In order to limit global mean temperature increase to less than 2°C, long-term greenhouse gas concentrations must remain low. This paper discusses how such low concentrations can be reached, based on results from the IMAGE modelling framework (including TIMER and FAIR). We show that the attainability of low greenhouse gas concentration targets, in particular 450 and 400 ppm CO2 equivalent critically depends on model assumptions, such as bio-energy potentials. Under standard model assumptions, these targets can be reached, although the lowest requires the use of bio-energy in combination with carbon-capture-and-storage. Regions are affected differently by ambitious climate policies in terms of energy and land use, although stringent emission reductions will be required in all regions. Resulting co-benefits of climate policy (such as energy security and air pollution) are also different across world regions.

This paper explores the potential for bio-energy production, and the implications of different values for the attainability of low stabilization targets. The impact of scenarios of future land use, yield improvements for bio-energy and available land under different sustainability assumptions (protection of biodiversity, risks of water scarcity and land degradation) are explored. Typical values for sustainable potential of bio-energy production are around 50-150 EJ in 2050 and 200-400 EJ in 2100. Higher bio-energy potential requires a development path with high agricultural yields, dietary patterns with low meat consumption, a low population and/or accepting high conversion rates of natural areas. Scenario analysis using four different models shows that low stabilization levels may be achieved with a bio-energy potential of around 200 EJ p.a. In such scenarios, bio-energy is in most models mainly used outside the transport sector.

Model analysis within the ADAM project has shown that achieving low greenhouse gas concentration levels, e.g. at 400ppm CO2-eq, is technologically feasible at costs of a few percent of GDP. However, models simplify the dynamics involved in implementing climate policy and the results depend on critical model assumptions such as global participation in climate policy and full availability of current and newly evolving technologies. The design of a low stabilization policy regime in the real world depends on factors that can only be partly covered by models. In this context, the paper reflects on limits of the integrated assessment models used to explore climate policy and addresses the issues of (i) how global participation might be achieved, (ii) which kind of options are available to induce deep GHG reductions inside and outside the energy sector, and (iii) which risks and which co-benefits of mitigation options are not assessed by the models.