Search

Climate impacts increasingly unfold in interlinked systems of people, nature, and infrastructure. The cascading consequences are revealing sometimes surprising connections across sectors and regions, and prospects for climate responses also depend on complex, difficult‐to‐understand interactions. In this commentary, we build on the innovations of the United States Fifth National Climate Assessment to suggest a framework for understanding and responding to complex climate challenges. This approach involves: (a) integration of disciplines and expertise to understand how intersectionality shapes complex climate impacts and the wide‐ranging effects of climate responses, (b) collaborations among diverse knowledge holders to improve responses and better encompass intersectionality, and (c) sustained experimentation with and learning about governance approaches capable of handling the complexity of climate change. Together, these three pillars underscore that usability of climate‐relevant knowledge requires transdisciplinary coordination of research and practice. We outline actionable steps for climate research to incorporate intersectionality, integration, and innovative governance, as is increasingly necessary for confronting climate complexity and sustaining equitable, ideally vibrant climate futures. Plain Language Summary: Climate impacts are complex, and prospects for climate responses depend on difficult‐to‐understand interactions. Lived experiences are increasingly revealing limits to what we in the scientific community have successfully modeled and ongoing challenges in how we help others understand the complexity of climate impacts and support decision‐making. Here, we chart a path for confronting the complexity of climate change with actionable advances in equity and governance research. Key Points: Climate impacts increasingly unfold in interlinked systems of people, nature, and infrastructureThe cascading consequences are revealing sometimes surprising connections and complex, difficult‐to‐understand interactionsWe suggest a research framework for climate complexity prioritizing intersectionality, integration, and innovative governance [ABSTRACT FROM AUTHOR]

Scenario analysis tools have emerged as a useful way to inform the policy debate by envisioning the potential evolution of energy systems over time. This dissertation describes three separate scenario analysis projects, each of which looks at the potential for a dramatic transformation of the energy system over the long term at varying geographic and sectoral scales. First, the 80in50 study analyzes the various pathways for making deep reductions in greenhouse gas emissions across all subsectors of U.S. transport system. The CA-TIMES project then takes this work to the next level by developing an energy-engineering-environmental-economic optimization model for the California energy system, in order to bring economics and dynamics into the analysis, as well as to study the interactions between transport and the various other energy producing and consuming sectors. Finally, a collaborative project with scientists at the International Institute for Applied Systems Analysis (IIASA) is described, in which a global systems engineering optimization model (MESSAGE) and a global climate model (MAGICC) are jointly utilized to evaluate synergies and trade-offs between a variety of energy objectives (climate mitigation, air pollution, energy security, and affordability)

Combined, aviation and marine transportation are responsible for approximately 5 percent of total greenhouse (GHG) emissions in the United States and 3 percent globally and are among the fastest growing modes in the transportation sector. Controlling the growth in these emissions will be an important part of reducing emissions from the transportation sector. A range of near-, medium- and long-term mitigation options are available to slow the growth of energy consumption and GHG emissions from aviation and marine shipping. Implementation of these options could result in reductions of more than 50 percent below BAU levels by 2050 from global aviation and more than 60 percent for global marine shipping. For these reductions to be realized, however, international and domestic policy intervention is required. Developing an effective path forward that facilitates the adoption of meaningful policies remains both a challenge and an opportunity.“Aviation and Marine Transportation: GHG Mitigation Potential and Challenges” presents an introduction to aviation and marine transportation and a discussion of the determinants of GHG emissions from transportation; gives overview of current emissions and trends and growth projections; explains the technological mitigation options and potential GHG emission reductions; and discusses policy options at both the domestic and international level to achieve deep and durable reductions in emissions.

This paper investigates how California may reduce transportation greenhouse gas emissions 80% below 1990 levels by 2050 (i.e., 80in50). A Kaya framework that decomposes greenhouse gas emissions into the product of population, transport intensity, energy intensity, and carbon intensity is used to analyze emissions and mitigation options. Each transportation subsector, including light-duty, heavy-duty, aviation, rail, marine, agriculture, and off-road vehicles, is analyzed to identify specific mitigation options and understand its potential for reducing greenhouse gas emissions. Scenario analysis shows that, while California’s 2050 target is ambitious, it can be achieved in transport if a concerted effort is made to change travel behavior and the vehicles and fuels that provide mobility. While no individual ‘‘Silver Bullet” strategy exists that can achieve the goals, a portfolio approach that combines strategies could yield success. The 80in50 scenarios show the impacts of advanced vehicle and fuels technologies as well as the role of travel demand reduction, which can significantly reduce energy and resource requirements and the level of technology development needed to meet the target.

Climate change in California could have a large impact on the state’s economy, natural and managed ecosystems, and human health and mortality. In an effort to mitigate such consequences, Governor Schwarzenegger signed Executive Order S-3-05 in 2005, and the state passed landmark legislation, the Global Warming Solutions Act (AB32), in 2006. The Executive Order calls for an 80% reduction in greenhouse gas (GHG) emissions relative to 1990 levels by 2050. The 80% reduction goal is not based on known mitigation options, but rather on emissions rates that are thought to be needed to stabilize atmospheric concentrations of GHGs before catastrophic climate changes occur. As a result, strategies for meeting this ambitious target have not been clearly defined, and the technology and policy options are not well understood. This report explores how the 80% reduction goal (80in50) may be met in the transportation sector, the largest contributor to GHG emissions in California.

After years of relatively slow growth, coal is undergoing a renaissance. Some 140 coal power plants are planned, and the Energy Information Administration (EIA) projects that the U.S. will consume almost 1,800 million tons of coal in 2030, up from about 1,150 million tons this year. In addition, while EIA’s estimates do not take coal-to-hydrogen production into consideration, several recent studies suggest that if the hydrogen economy ever comes to fruition coal could be a feedstock of choice, at least in the U.S. which has huge reserves of coal (~250 years’ worth at current consumption rates), which are relatively cheap and easy to mine.An increase in future coal demand fuels legitimate concerns about the impacts on global climate and regional air pollution. While carbon capture and storage is often mentioned as a solution to these two problems, another impact, often overlooked, is the possibility that the current coal distribution infrastructure may not be able to reliably deliver the additional demand. Railroads deliver about two-thirds of U.S. coal at present, but certain coal-carrying rail corridors are already up against their capacity limits. Any future demand increases will probably necessitate significant capital investment by rail companies.This study seeks to identify existing capacity and potential constraints within the coal distribution infrastructure and to identify the costs of alleviating these constraints under several growth scenarios for coal demand. The scenarios differ based on whether or not pulverized coal (PC) or integrated gasification combined cycle (IGCC) power plants are built, as well as the amount of coal that is used to produce hydrogen for fuel cell vehicles.Coal transportation along the nation’s vast rail network is modeled with a freight routing model that uses the Surface Transportation Board’s confidential Carload Waybill Sample data as an input. For each coal demand growth scenario, I identify the rail corridors that could potentially reach their capacity limits in the future due to increasing coal traffic, and I quantify the investment that might be needed to boost the coal-carrying capacity along these lines.Some of important questions that I have attempted to answer through this analysis include the following: (1) Will the nation’s rail-coal distribution system be able to handle the future increases in coal demand that could result from traditional uses, as well as from coal-to-hydrogen production; and (2) What is the trade-off between building more efficient, albeit more expensive, IGCC power plants versus modern PC plants, if costly investments in coal transportation infrastructure can be avoided?

Due to a heightened interest in technologies to mitigate global climate change, research in the field of carbon capture and storage (CCS) has attracted greater attention in recent years, with the goal of answering the many questions that still remain in this uncertain field. At the top of the list of key issues are CCS costs: costs of carbon dioxide (CO2) capture, compression, transport, storage, and so on. This research report touches upon several of these cost components. It also provides some technical models for determining the engineering and infrastructure requirements of CCS, and describes some correlations for estimating CO2 density and viscosity, both of which are often essential properties for modeling CCS. This report is actually a compilation of three separate research reports and is, therefore, divided into three separate sections. But although each could be considered as a stand-alone research report, they are, in fact, very much related to one other. Section I builds upon some of the knowledge from the latter sections, and Sections II & III can be considered as supplementary to Section I.* Section I: Techno-Economic Models for Carbon Dioxide Compression, Transport, and Storage – This section provides models for estimating the engineering requirements and costs of CCS infrastructure. Some of the models have been adapted from other studies, while others have been expressly developed in this study. * Section II: Simple Correlations for Estimating Carbon Dioxide Density and Viscosity as a Function of Temperature and Pressure – This section describes a set of simple correlations for estimating the density and viscosity of CO2 within the range of operating temperatures and pressures that might be encountered in CCS applications. The correlations are functions of only two input parameters—temperature and pressure—which makes them different from the more complex equation of state computer code-based correlations that sometimes require more detailed knowledge of CO2 properties and operating conditions. * Section III: Comparing Techno-Economic Models for Pipeline Transport of Carbon Dioxide – This section illustrates an approach that was used to compare several recent techno-economic models for estimating CO2 pipeline sizes and costs. A common set of input assumptions was applied to all of the models so that they could be compared on an “apples-to-apples” basis. Then, by averaging the cost estimates of the models over a wide range of CO2 mass flow rates and pipeline lengths, a new CO2 pipeline capital cost model was created that is a function only of flow rate and pipeline length.

For more than a decade, the target of keeping global warming below 2 ° C has been a key focus of the international climate debate. (1) In response, the scientific [...]

Adopting electric end-use technologies instead of fossil-fueled alternatives, known as electrification, is an important economy-wide decarbonization strategy that also reduces criteria pollutant emissions and improves air quality. In this study, we evaluate CO2 and air quality co-benefits of electrification scenarios by linking a detailed energy systems model and a full-form photochemical air quality model in the United States. We find that electrification can substantially lower CO2 and improve air quality and that decarbonization policy can amplify these trends, which yield immediate and localized benefits. In particular, transport electrification can improve ozone and fine particulate matter (PM2.5), though the magnitude of changes varies regionally. However, growing activity from non-energy-related PM2.5 sources—such as fugitive dust and agricultural emissions—can offset electrification benefits, suggesting that additional measures beyond CO2 policy and electrification are needed to meet air quality goals. We illustrate how commonly used marginal emissions approaches systematically underestimate reductions from electrification. Electrification is a decarbonization strategy that has the potential to reduce pollutant emissions and improve air quality. Here the authors evaluate CO2 and air quality co-benefits of electrification scenarios in the United States and find that electrification can substantially lower CO2 and improve ozone and fine particulate matter regionally. [ABSTRACT FROM AUTHOR]