John P. Weyant

The next generation of scenarios for climate change research and assessment

Advances in the science and observation of climate change are providing a clearer understanding of the inherent variability of Earth’s climate system and its likely response to human and natural influences. The implications of climate change for the environment and society will depend not only on the response of the Earth system to changes in radiative forcings, but also on how humankind responds through changes in technology, economies, lifestyle and policy. Extensive uncertainties exist in future forcings of and responses to climate change, necessitating the use of scenarios of the future to explore the potential consequences of different response options. To date, such scenarios have not adequately examined crucial possibilities, such as climate change mitigation and adaptation, and have relied on research processes that slowed the exchange of information among physical, biological and social scientists. Here we describe a new process for creating plausible scenarios to investigate some of the most challenging and important questions about climate change confronting the global community.

Approaches for performing uncertainty analysis in large-scale energy/economic policy models

A number of key policy insights have emerged from the application of large-scale economic/energy models, such as integrated assessment models for climate change. These insights have been particularly powerful in those instances when they are shared by all or most of the existing models. On the other hand, some results and policy recommendations obtained from integrated assessment models vary widely from model to model. This can limit their usability for policy analysis. The differences between model results are mostly due to different underlying assumptions about exogenous processes, about endogenous processes and the dynamics among them, differences in value judgments, and different approaches for simplifying model structure for computational purposes. Uncertainty analyses should be performed for the dual purpose of clarifying the uncertainties inherent in model results and improving decision making under uncertainty. This paper develops a unifying framework for comparing the different types of uncertainty analyses through their objective functions, categorizes types of uncertainty analyses that can be performed on large models, and compares different approaches to uncertainty analysis by explaining underlying assumptions, suitability for different model types, and advantages and disadvantages. The appendix presents a summary of integrated assessment models for climate change that explicitly account for uncertainty.

Issues in modeling induced technological change in energy, environmental, and climate policy

This paper addresses the objective of including Induced Technological Change (ITC) in research and policy models of energy, environment, and climate change. Theoretical foundations, fundamentals, and current methodologies for ITC models are reviewed. In addition, limitations and possible extensions to ITC models are explored. Current approaches to energy-environmental modeling that neglect technological characteristics such as heterogeneity, uncertainty, and path-dependence are likely to underestimate both the impact and the lags in the effectiveness of policy options.

Climate Suitability for Stable Malaria Transmission in Zimbabwe Under Different Climate Change Scenarios

Climate is one factor that determines the potential range of malaria. As such, climate change may work with or against efforts to bring malaria under control. We developed a model of future climate suitability for stable Plasmodium falciparum malaria transmission in Zimbabwe. Current climate suitability for stable malaria transmission was based on the MARA/ARMA model of climatic constraints on the survival and development of the Anopheles vector and the Plasmodium falciparum malaria parasite. We explored potential future geographic distributions of malaria using 16 projections of climate in 2100. The results suggest that, assuming no future human-imposed constraints on malaria transmission, changes in temperature and precipitation could alter the geographic distribution of malaria in Zimbabwe, with previously unsuitable areas of dense human population becoming suitable for transmission. Among all scenarios, the highlands become more suitable for transmission, while the lowveld and areas with low precipitation show varying degrees of change, depending on climate sensitivity and greenhouse gas emission stabilization scenarios, and depending on the general circulation model used. The methods employed can be used within or across other African countries.

Feature Article-Energy Policy Modeling: A Survey

This survey provides an exposition of seven technoeconomic models that are representative of recent work on energy policy. The paper begins with several microeconomic concepts related to energy conservation and to energy-economy interactions. We then examine three representative medium-term models which deal with pricing, import policy and investment decisions in todays conventional supply technologies. Next, we analyze four studies dealing with longer-range issues-alternative research and development strategies for a transition away from depletable energy resources. The paper concludes with a summary of unresolved issues, and with suggestions on the future role of modeling in the public policy process.

Evaluation of a proposal for reliable low-cost grid power with 100% wind, water, and solar

A number of analyses, meta-analyses, and assessments, including those performed by the Intergovernmental Panel on Climate Change, the National Oceanic and Atmospheric Administration, the National Renewable Energy Laboratory, and the International Energy Agency, have concluded that deployment of a diverse portfolio of clean energy technologies makes a transition to a low-carbon-emission energy system both more feasible and less costly than other pathways. In contrast, Jacobson et al. [Jacobson MZ, Delucchi MA, Cameron MA, Frew BA (2015) Proc Natl Acad Sci USA 112(49):15060–15065] argue that it is feasible to provide “low-cost solutions to the grid reliability problem with 100% penetration of WWS [wind, water and solar power] across all energy sectors in the continental United States between 2050 and 2055”, with only electricity and hydrogen as energy carriers. In this paper, we evaluate that study and find significant shortcomings in the analysis. In particular, we point out that this work used invalid modeling tools, contained modeling errors, and made implausible and inadequately supported assumptions. Policy makers should treat with caution any visions of a rapid, reliable, and low-cost transition to entire energy systems that relies almost exclusively on wind, solar, and hydroelectric power. Significance Previous analyses have found that the most feasible route to a low-carbon energy future is one that adopts a diverse portfolio of technologies. In contrast, Jacobson et al. (2015) consider whether the future primary energy sources for the United States could be narrowed to almost exclusively wind, solar, and hydroelectric power and suggest that this can be done at “low-cost” in a way that supplies all power with a probability of loss of load “that exceeds electric-utility-industry standards for reliability”. We find that their analysis involves errors, inappropriate methods, and implausible assumptions. Their study does not provide credible evidence for rejecting the conclusions of previous analyses that point to the benefits of considering a broad portfolio of energy system options. A policy prescription that overpromises on the benefits of relying on a narrower portfolio of technologies options could be counterproductive, seriously impeding the move to a cost effective decarbonized energy system.

A Critique of the Stern Review's Mitigation Cost Analyses and Integrated Assessment

This article is an assessment of the Stern Review on the Economics of Climate Change, a major climate policy study done for the UK government by a group led by Sir Nicholas Stern. In this article, I examine both the mitigation cost and integrated assessment aspects of the Review. Although the Review makes many significant contributions, I believe that the framework the Review adopted to formulate policy recommendations is difficult to understand, and probably not well matched to the problem being addressed, and that the Reviews specific recommendation for large emission reductions in the short run to facilitate stabilization of greenhouse gases in the atmosphere by mid-century is not justified by the analysis. This outcome was the result of using relatively high climate damage projections, relatively low GHG mitigation cost projections, and very low discount rate assumptions relative to current expert opinion and what is in the literature. Moreover, the Reviews formulation appears to treat the climate policy problem as a deterministic “one shot” benefit-cost analysis rather than a problem of sequential decision-making under uncertainty.

Industrial energy demand: A simple structural approach☆

Abstract This paper describes a simple structural model of industrial energy demand based on production-function-like concepts, with vintaging of the available capital stock. The model is designed to help users understand the past and likely future effects of variations in factor prices and rates of output growth on industrial energy demands by major industry group. The approach handles capital-stock adjustment, electric/non-electric energy competition and business cycle effects in a simple, but natural, way. A description of an interesting initial application of the model to the primary metals industry is also included. This application improves our understanding of the approach, and demonstrates its usefulness in industrial energy demand analysis.

Electrification of the economy and CO 2 emissions mitigation

In this article, the ratio of central station electricity to final energy is used as a measure of electrification. It is well known that this ratio tends to increase with gross domestic product. We show that not only is electrification a characteristic of a reference case with economic growth, but that it is significantly accelerated by a general limitation on carbon emissions. That is, limits on CO2 concentrations, implemented efficiently across the whole economy, result in a higher ratio of electricity to total final energy use. This result reflects the relatively greater suite of options available in reducing CO2 emissions in power generation than in other important components of the economy. Furthermore, electrification is stronger, the more stringent the constraint on CO2 emissions, although the absolute production of electricity may be either greater or smaller in the presence of a CO2 constraint, depending on the technologies available to the sector and to end-use sectors. The base technology scenario we examined was purposefully pessimistic about the evolution of central station and distributed electric technologies, lessening the degree of electrification. The better the performance of the set of options for emissions mitigation in power generation, the greater the acceleration of electrification.

Technology and U.S. Emissions Reductions Goals: Results of the EMF 24 Modeling Exercise

This paper discusses Technology and U.S. Emissions Reductions Goals: Results of the EMF 24 Modeling Exercise