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Applying engineering and fleet detail to represent passenger vehicle transport in a computable general equilibrium model

A well-known challenge in computable general equilibrium (CGE) models is to maintain correspondence between the forecasted economic and physical quantities over time. Maintaining such a correspondence is necessary to understand how economic forecasts reflect, and are constrained by, relationships within the underlying physical system. This work develops a method for projecting global demand for passenger vehicle transport, retaining supplemental physical accounting for vehicle stock, fuel use, and greenhouse gas (GHG) emissions. This method is implemented in the MIT Emissions Prediction and Policy Analysis Version 5 (EPPA5) model and includes several advances over previous approaches. First, the relationship between per-capita income and demand for passenger vehicle transport services (in vehicle-miles traveled, or VMT) is based on econometric estimates and modeled using quasi-homothetic preferences. Second, the passenger vehicle transport sector is structured to capture opportunities to reduce fleet-level gasoline use through the application of vehicle efficiency or alternative fuel vehicle technologies, introduction of alternative fuels, or reduction in demand for VMT. Third, alternative fuel vehicles (AFVs) are represented in the EPPA model. Fixed costs as well as learning effects that could influence the rate of AFV introduction are captured explicitly. This model development lays the foundation for assessing policies that differentiate based on vehicle age and efficiency, alter the relative prices of fuels, or focus on promoting specific advanced vehicle or fuel technologies.

© 2012 Elsevier B.V.

Energy Scenarios: The Value and Limits of Scenario Analyses

A need for a low-carbon world has added a new challenging dimension for long-term energy scenarios development. In addition to the traditional factors like technological progress and demographic, economic, political and institutional considerations, there is another aspect of modern energy forecasts related to the coverage, timing and stringency of policies to mitigate greenhouse gas emissions and air pollutants. Modern tools for energy scenario development provide a good basis for estimates of the required changes in the energy system to achieve certain climate and environmental targets. While current scenarios show that a move to a low- carbon energy future requires a drastic change in energy investment and the resulting mix in energy technologies, the exact technology mix, paths to the needed mix, price and cost projections should be treated with a great degree of caution. The scenarios do not provide exact predictions, but they can be used as a qualitative analysis of decision-making risks associated with different pathways. If history is any guide, energy scenarios overestimate the extent to which the future will look like the recent past. As future costs and the resulting technology mixes are uncertain, a wise government policy is to target emissions reductions from any source, rather than focus on boosting certain kinds of low-carbon energy.

Teaching and Learning from Environmental Summits: COP 21 and Beyond

High-profile environmental summits like the recent Paris climate conference (COP 21) offer an opportunity to incorporate real-world, timely issues into teaching and learning about global environmental governance. Using COP 21 as an example, this Forum article summarizes the ways that contemporary environmental summits can be incorporated into university-level education, providing content and context to help address the challenges of interdisciplinary sustainability education. Faculty members have incorporated COP-21-related content in ways ranging from traditional lectures and discussions to field trips, which have contributed to a broad range of course content and learning goals. However, the challenges of including environmental summits in educational settings include knowledge-based, normative, and structural barriers. While environmental summits can be an effective way to incorporate knowledge of global environmental governance into interdisciplinary education, more resources, experimentation, and extensions beyond climate change are needed.

With the eyes of the world on Paris in December 2015, the eyes of students were among them. For those of us who teach about global environmental politics, this presented both a challenge and an opportunity. Environmental summits offer high-profile examples of how cooperation and conflict about ways to address environmental challenges happen in real-world settings. The impact of high-profile events like COP 21 extends well beyond the academic community that traditionally studies environmental governance.

While experts in global environmental politics are often well-acquainted with the role and importance of summits, the issues addressed at summits are relevant to a much broader community of scholarship. Addressing large-scale, complex global environmental and sustainability problems like climate change requires mobilizing a broad range of expertise from across disciplines (Holdren 2008), including perspectives on global environmental governance. Future researchers and practitioners in a variety of disciplines need training and expertise that prepare them to integrate and apply different types of knowledge to real-world problems. Here, I examine whether environmental summits such as COP 21 can provide content and context to help address this interdisciplinary challenge in sustainability education. Drawing on my own experience incorporating environmental negotiations in classroom education, and on insights from colleagues through an online survey and personal interviews, I reflect on the ways in which faculty members at universities engaged with COP 21, lessons learned, and challenges ahead. I focus on university-level classroom settings (as opposed to educational activities for K–12 students, the general public, or education in other forms than traditional classes) in a broad range of disciplines. First, I summarize the varying ways in which faculty can incorporate environmental summits into education, and assess how this live, real-world content can affect educational outcomes. I then identify challenges and roadblocks to teaching and learning from summits in interdisciplinary settings, including knowledge-based, normative, and structural barriers. Finally, I conclude by recommending concrete ways forward for improved outcomes when incorporating environmental summits in multidisciplinary coursework.

The complicated geopolitics of renewable energy

A recent UN climate agreement has the potential to shift global energy consumption from a mix dominated by fossil fuels to one driven by low-carbon technologies. It is clear that if this happens, fossil-fuel-producing countries will have to adjust their economies to reflect lower export earnings from oil, coal, and natural gas. The rise of renewable energy may also create new centers of geopolitical power. As renewable resources become widely distributed, supply-side geopolitics are expected to be less influential than in the fossil-fuel era. Instead of focusing on just two major resources, oil and natural gas, low-carbon energy geopolitics may depend on many additional factors, such as access to technology, power lines, rare earth materials, patents, storage, and dispatch, not to mention unpredictable government policies. Despite uncertainty, there is no question that the balance of power in energy geopolitics is shifting from fossil-fuel owners to countries that are developing low-carbon solutions.

The Impact of Oil Prices on Bioenergy, Emissions and Land Use

We evaluate how alternative future oil prices will influence the penetration of biofuels, energy production, greenhouse gas (GHG) emissions, land use and other outcomes. Our analysis employs a global economy wide model and simulates alternative oil prices out to 2050 with and without a price on GHG emissions. In one case considered, based on estimates of available resources, technological progress and energy demand, the reference oil price rises to $124 by 2050. Other cases separately consider constant reference oil prices of $50, $75 and $100, which are targeted by adjusting the quantity of oil resources. In our simulations, higher oil prices lead to more biofuel production, more land being used for bioenergy crops, and fewer GHG emissions. Reducing oil resources to simulate higher oil prices has a strong income effect, so decreased food demand under higher oil prices results in an increase in land allocated to natural forests. We also find that introducing a carbon price reduces the differences in oil use and GHG emissions across oil price cases.

Top-down estimates of benzene and toluene emissions in the Pearl River Delta and Hong Kong, China

Benzene (C6H6) and toluene (C7H8) are toxic to humans and the environment. They are also important precursors of ground-level ozone and secondary organic aerosols and contribute substantially to severe air pollution in urban areas in China. Discrepancies exist between different bottom-up inventories for benzene and toluene emissions in the Pearl River Delta (PRD) and Hong Kong (HK), which are emission hot spots in China. This study provides top-down estimates of benzene and toluene emissions in the PRD and HK using atmospheric measurement data from a rural site in the area, Heshan, an atmospheric transport model, and an inverse modeling method. The model simulations captured the measured mixing ratios during most pollution episodes. For the PRD and HK, the benzene emissions estimated in this study for 2010 were 44"¯(12–75) and 5"¯(2–7)"¯Gg"¯yr−1 for the PRD and HK, respectively, and the toluene emissions were 131"¯(44–218) and 6"¯(2–9)"¯Gg"¯yr−1, respectively. Temporal and spatial differences between the inversion estimate and four different bottom-up emission estimates are discussed, and it is proposed that more observations at different sites are urgently needed to better constrain benzene and toluene (and other air pollutant) emissions in the PRD and HK in the future.

Uncertainties in Atmospheric Mercury Modeling for Policy Evaluation

Mercury (Hg) contamination is an issue of a growing environmental and public health concern. Atmospheric chemistry transport models for Hg are a critical tool for understanding the sources, processes, and fate of Hg. Uncertainties in multiple aspects of atmospheric Hg models, however, limit their application for policy evaluation and for monitoring global trends in atmospheric Hg concentrations. This review aims to identify uncertainties in atmospheric Hg modeling that are relevant in the context of policy and for informing decision-making. We focus on specific requirements of the Minamata Convention on Mercury, a global treaty signed in 2013 to protect human health and the environment from Hg, to demonstrate how existing uncertainties in atmospheric Hg modeling can influence our ability to evaluate source-receptor relationships. Modeling studies of source attribution suggest that major uncertainties in atmospheric Hg modeling arise from anthropogenic emissions, biogeochemical cycling, and atmospheric chemistry. Uncertainties in these aspects of modeling are expected to increase under the Convention, with regulation of anthropogenic emissions, changes in atmospheric conditions, and legacy and natural Hg source contribution to the global biogeochemical cycle. These uncertainties can interact with one another and with the current Hg species measurement capability and pose challenges to effectively monitoring trends in atmospheric Hg. Developing additional means to attribute simulated atmospheric Hg trends and improve source-receptor relationships in atmospheric Hg models would improve our ability to evaluate the Convention’s effectiveness.

© Springer International Publishing AG 2016

Statistical Emulators of Maize, Rice, Soybean and Wheat Yields from Global Gridded Crop Models

This study provides statistical emulators of crop yields based on global gridded crop model simulations from the Inter-Sectoral Impact Model Intercomparison Project Fast Track project. The ensemble of simulations is used to build a panel of annual crop yields from five crop models and corresponding monthly summer weather variables for over a century at the grid cell level globally. This dataset is then used to estimate, for each crop and gridded crop model, the statistical relationship between yields, temperature, precipitation and carbon dioxide. This study considers a new functional form to better capture the non-linear response of yields to weather, especially for extreme temperature and precipitation events. In- and out-of-sample validations show that the statistical emulators are able to closely replicate crop yields projected by crop models and perform well out-of-sample. This study therefore provides a reliable and accessible alternative to global gridded crop yield models. By emulating crop yields for several models using parsimonious equations, the tools provide a computationally efficient method to account for uncertainty in climate change impact assessments.

The Global Energy, CO2 Emissions, and Economic Impact of Vehicle Fuel Economy Standards

Fuel economy standards for new light-duty passenger vehicles have recently been adopted or tightened in many nations. Using a global computable general equilibrium (CGE) model, we analyse the combined effect of existing and accelerated national and regional fuel economy standards on demand for petroleum-based fuels, CO2 emissions, and economic cost, and compare the results to a carbon pricing scenario with identical emissions reductions. We find that fuel economy standards are less cost-effective than a carbon price, with year-on-year consumption loss rising to 10 per cent of global GDP in 2050 under fuel economy standards, compared with 6 per cent under carbon pricing.

© 2015 JTEP

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