• Energy Research

Abstract For the option of “carbon capture and storage”, an integrated assessment in the form of a life cycle analysis and a cost assessment combined with a systematic comparison with renewable energies regarding future conditions in the power plant market for the situation in Germany is done. The calculations along the whole process chain show that CCS technologies emit per kWh more than generally assumed in clean-coal concepts (total CO2 reduction by 72–90% and total greenhouse gas reduction by 65–79%) and considerable more if compared with renewable electricity. Nevertheless, CCS could lead to a significant absolute reduction of GHG-emissions within the electricity supply system. Furthermore, depending on the growth rates and the market development, renewables could develop faster and could be in the long term cheaper than CCS based plants. Especially, in Germany, CCS as a climate protection option is phasing a specific problem as a huge amount of fossil power plant has to be substituted in the next 15 years where CCS technologies might be not yet available. For a considerable contribution of CCS to climate protection, the energy structure in Germany requires the integration of capture ready plants into the current renewal programs. If CCS retrofit technologies could be applied at least from 2020, this would strongly decrease the expected CO2 emissions and would give a chance to reach the climate protection goal of minus 80% including the renewed fossil-fired power plants.

We provide a rejoinder to a review (Rosen, 2015) of our original article "Making or breaking climate targets - the AMPERE study on staged accession scenarios for climate policy" (Kriegler et al., 2015a). We have a substantial disagreement with the content of the review, and feel that it is plagued by a number of misconceptions about the nature of the AMPERE study and the integrated assessment modeling approach employed by it. We therefore see this rejoinder as an opportunity to clarify these misconceptions and advance the debate by providing a clearer understanding of the strengths, weaknesses, and ultimately the value of integrated assessment.

Abstract International emissions trading is widely seen as an indispensable policy pillar of climate change mitigation [Stern, N., 2007. The Economics of Climate Change. The Stern Review. Cambridge University Press, New York]. This article analyzes five different types of trading architectures, classified into two top–down (UNFCCC driven) and three bottom–up (driven by individual countries or regions) approaches. The two types of approaches are characterized by a trade-off between environmental effectiveness and political feasibility, respectively, whereas their relative cost-effectiveness depends on implementation details. Bottom–up architectures constitute imperfect substitutes for top–down architectures in terms of environmental effectiveness, and thus remain mere fallback options. However, especially the ‘formal linking’ architecture can act as complement in terms of cost-effectiveness.

This article explores efficient climate policies in terms of investment streams into fossil and renewable energy technologies. The investment decisions maximise social welfare while observing a probabilistic guardrail for global mean temperature rise under uncertain technology and climate parameters. Such a guardrail constitutes a chance constraint, and the resulting optimisation problem is an instance of chance constrained programming, not stochastic programming as often employed. Our analysis of a model of economic growth and endogenous technological change, MIND, suggests that stringent mitigation strategies cannot guarantee a very high probability of limiting warming to 2 °C since preindustrial time under current uncertainty about climate sensitivity and climate response time scale. Achieving the 2 °C temperature target with a probability P* of 75% requires drastic carbon dioxide emission cuts. This holds true even though we have assumed an aggressive mitigation policy on other greenhouse gases from, e.g., the agricultural sector. The emission cuts are deeper than estimated from a deterministic calculation with climate sensitivity fixed at the P* quantile of its marginal probability distribution (3.6 °C). We show that earlier and cumulatively larger investments into the renewable sector are triggered by including uncertainty in the technology and climate response time scale parameters. This comes at an additional GWP loss of 0.3%, resulting in a total loss of 0.8% GWP for observing the chance constraint. We obtained those results with a new numerical scheme to implement constrained welfare optimisation under uncertainty as a chance constrained programming problem in standard optimisation software such as GAMS. The scheme is able to incorporate multivariate non-factorial probability measures such as given by the joint distribution of climate sensitivity and response time. We demonstrate the scheme for the case of a four-dimensional parameter space capturing uncertainty about climate and technology.

Abstract This paper presents a set of energy and resource intensive scenarios based on the concept of Shared Socio-Economic Pathways (SSPs). The scenario family is characterized by rapid and fossil-fueled development with high socio-economic challenges to mitigation and low socio-economic challenges to adaptation (SSP5). A special focus is placed on the SSP5 marker scenario developed by the REMIND-MAgPIE integrated assessment modeling framework. The SSP5 baseline scenarios exhibit very high levels of fossil fuel use, up to a doubling of global food demand, and up to a tripling of energy demand and greenhouse gas emissions over the course of the century, marking the upper end of the scenario literature in several dimensions. These scenarios are currently the only SSP scenarios that result in a radiative forcing pathway as high as the highest Representative Concentration Pathway (RCP8.5). This paper further investigates the direct impact of mitigation policies on the SSP5 energy, land and emissions dynamics confirming high socio-economic challenges to mitigation in SSP5. Nonetheless, mitigation policies reaching climate forcing levels as low as in the lowest Representative Concentration Pathway (RCP2.6) are accessible in SSP5. The SSP5 scenarios presented in this paper aim to provide useful reference points for future climate change, climate impact, adaption and mitigation analysis, and broader questions of sustainable development.

We investigate how different designs of carbon offset mechanisms, like theKyotoProtocol'sCleanDevelopmentMechanism (CDM), affect the success of self‐enforcing climate treaties. In a game‐theoretic numerical model of coalition formation we find that participation in the agreement is negatively affected when strategic behavior and free‐rider incentives matter. This does not change when selling targets restrict credit supply. Substantially higher participation emerges when the treaty restricts its signatories not to use the gains from credit trading to lower their emission caps. Despite the high sensitivity of participation to differentCDMdesign, we find that global welfare levels achieved in various equilibria are remarkably similar.