Christopher L. Weber

Growth in emission transfers via international trade from 1990 to 2008

Despite the emergence of regional climate policies, growth in global CO2 emissions has remained strong. From 1990 to 2008 CO2 emissions in developed countries (defined as countries with emission-reduction commitments in the Kyoto Protocol, Annex B) have stabilized, but emissions in developing countries (non-Annex B) have doubled. Some studies suggest that the stabilization of emissions in developed countries was partially because of growing imports from developing countries. To quantify the growth in emission transfers via international trade, we developed a trade-linked global database for CO2 emissions covering 113 countries and 57 economic sectors from 1990 to 2008. We find that the emissions from the production of traded goods and services have increased from 4.3 Gt CO2 in 1990 (20% of global emissions) to 7.8 Gt CO2 in 2008 (26%). Most developed countries have increased their consumption-based emissions faster than their territorial emissions, and non–energy-intensive manufacturing had a key role in the emission transfers. The net emission transfers via international trade from developing to developed countries increased from 0.4 Gt CO2 in 1990 to 1.6 Gt CO2 in 2008, which exceeds the Kyoto Protocol emission reductions. Our results indicate that international trade is a significant factor in explaining the change in emissions in many countries, from both a production and consumption perspective. We suggest that countries monitor emission transfers via international trade, in addition to territorial emissions, to ensure progress toward stabilization of global greenhouse gas emissions.

A "carbonizing dragon": China's fast growing CO2 emissions revisited.

Chinas annual CO(2) emissions grew by around 4 billion tonnes between 1992 and 2007. More than 70% of this increase occurred between 2002 and 2007. While growing export demand contributed more than 50% to the CO(2) emission growth between 2002 and 2005, capital investments have been responsible for 61% of emission growth in China between 2005 and 2007. We use structural decomposition analysis to identify the drivers for Chinas emission growth between 1992 and 2007, with special focus on the period 2002 to 2007 when growth was most rapid. In contrast to previous analysis, we find that efficiency improvements have largely offset additional CO(2) emissions from increased final consumption between 2002 and 2007. The strong increases in emissions growth between 2002 and 2007 are instead explained by structural change in Chinas economy, which has newly emerged as the third major emission driver. This structural change is mainly the result of capital investments, in particular, the growing prominence of construction services and their carbon intensive supply chain. By closing the model for capital investment, we can now show that the majority of emissions embodied in capital investment are utilized for domestic household and government consumption (35-49% and 19-36%, respectively) with smaller amounts for the production of exports (21-31%). Urbanization and the associated changes in lifestyle are shown to be more important than other socio-demographic drivers like the decreasing household size or growing population. We argue that mitigation efforts will depend on the future development of these key drivers, particularly capital investments which dictate future mitigation costs.

Life cycle carbon footprint of shale gas: review of evidence and implications.

The recent increase in the production of natural gas from shale deposits has significantly changed energy outlooks in both the US and world. Shale gas may have important climate benefits if it displaces more carbon-intensive oil or coal, but recent attention has discussed the potential for upstream methane emissions to counteract this reduced combustion greenhouse gas emissions. We examine six recent studies to produce a Monte Carlo uncertainty analysis of the carbon footprint of both shale and conventional natural gas production. The results show that the most likely upstream carbon footprints of these types of natural gas production are largely similar, with overlapping 95% uncertainty ranges of 11.0-21.0 g CO(2)e/MJ(LHV) for shale gas and 12.4-19.5 g CO(2)e/MJ(LHV) for conventional gas. However, because this upstream footprint represents less than 25% of the total carbon footprint of gas, the efficiency of producing heat, electricity, transportation services, or other function is of equal or greater importance when identifying emission reduction opportunities. Better data are needed to reduce the uncertainty in natural gass carbon footprint, but understanding system-level climate impacts of shale gas, through shifts in national and global energy markets, may be more important and requires more detailed energy and economic systems assessments.

Hybrid Framework for Managing Uncertainty in Life Cycle Inventories

Life cycle assessment (LCA) is increasingly being used to inform decisions related to environmental technologies and polices, such as carbon footprinting and labeling, national emission inventories, and appliance standards. However, LCA studies of the same product or service often yield very different results, affecting the perception of LCA as a reliable decision tool. This does not imply that LCA is intrinsically unreliable; we argue instead that future development of LCA requires that much more attention be paid to assessing and managing uncertainties. In this article we review past efforts to manage uncertainty and propose a hybrid approach combining process and economic inputoutput (I-O) approaches to uncertainty analysis of life cycle inventories (LCI). Different categories of uncertainty are sometimes not tractable to analysis within a given model framework but can be estimated from another perspective. For instance, cutoff or truncation error induced by some processes not being included in a bottom-up process model can be estimated via a top-down approach such as the economic I-O model. A categorization of uncertainty types is presented (data, cutoff, aggregation, temporal, geographic) with a quantitative discussion of methods for evaluation, particularly for assessing temporal uncertainty. A long-term vision for LCI is proposed in which hybrid methods are employed to quantitatively estimate different uncertainty types, which are then reduced through an iterative refinement of the hybrid LCI method.

Life Cycle Assessment and Grid Electricity: What Do We Know and What Can We Know?

The generation and distribution of electricity comprises nearly 40% of U.S. CO(2), emissions, as well as large shares of SO(2), NO(x), small particulates, and other toxins. Thus, correctly accounting for these electricity-related environmental releases is of great importance in life cycle assessment of products and processes. Unfortunately, there is no agreed-upon protocol for accounting for the environmental emissions associated with electricity, as well as significant uncertainty in the estimates. Here, we explore the limits of current knowledge about grid electricity in LCA and carbon footprinting for the U.S. electrical grid, and show that differences in standards, protocols, and reporting organizations can lead to important differences in estimates of CO(2) SO(2), and NO(x) emissions factors. We find a considerable divergence in published values for grid emissions factor in the U.S. We discuss the implications of this divergence and list recommendations for a standardized approach to accounting for air pollution emissions in life cycle assessment and policy analyses in a world with incomplete and uncertain information.

THE ROLE OF INPUT-OUTPUT ANALYSIS FOR THE SCREENING OF CORPORATE CARBON FOOTPRINTS

In developing a standardised approach for companies to inventory greenhouse gas (GHG) emissions along their value chains, key challenges identified by stakeholders and technical experts include: which emissions sources a company should include in their inventory and how to calculate them, what constitutes a full list of indirect supply chain activities, and how to determine which activities from such a list are significant by application of a cut-off threshold. Using GHG accounting based on input–output models from Australia and the United States, this work presents specific case study examples and general results for broad industry sectors in both economies to address the development of a complete upstream carbon footprint for screening purposes. This is followed by an analysis of the issues surrounding application of cut-off thresholds and the relationship with system capture rate and efforts in carbon footprint analysis. This knowledge can inform decision makers about where to expend effort in gaining progressively greater accuracy for informed purchasing, investing, claiming carbon credits, and policy-making. The results from this work elucidate several findings: while it is probably true that some companies will know what sources contribute most significantly in the supply chain, this is not likely to be true for all. Contrary to common perception, scope 1&2 emissions are not always more significant than scope-3 sources, and, for some sectors, the largest sources of emissions may be buried further upstream than many companies may have previously perceived. Compiling a list of core elements of significance across all sectors may be problematic because these elements are not necessarily significant for most sectors. Lastly, the application of cut-off thresholds results in highly variable performance in footprint capture rate and is not a reliable criterion for including emission sources in GHG footprints. Input–output analysis is a powerful tool in informing supply-chain GHG accounting, and there is a need for plain language education, training, support materials and information to be made easily accessible to a global business community.

The Energy and Climate Change Implications of Different Music Delivery Methods

The impacts of information and communications technology (ICT) on the environment have been a rich area for research in recent years. A prime example is the continuing rise of digital music delivery, which has obvious potential for reducing the energy and environmental impacts of producing and delivering music to final consumers. This study assesses the energy and carbon dioxide (CO) emissions associated with several alternative methods for delivering one album of music to a final customer, either through traditional retail or e-commerce sales of compact discs or through a digital download service. We analyze a set of six (three compact disc and three digital download) scenarios for the delivery of one music album from the recording stage to the consumers home in either CD or digital form. We find that despite the increased energy and emissions associated with Internet data flows, purchasing music digitally reduces the energy and carbon dioxide (CO) emissions associated with delivering music to customers by between 40% and 80% from the best-case physical CD delivery, depending on whether a customer then burns the files to CD. Despite the dominance of the digital music delivery method, however, there are scenarios by which digital music performs less well, and these scenarios are explored. We suggest future areas of research, including alternative digital media services, such as subscription and streaming systems, for which Internet energy usage may be larger than for direct downloads.

Life cycle comparison of traditional retail and e-commerce logistics for electronic products: A case study of buy.com

This analysis compares e-commerce versus traditional retail systems energy use and greenhouse gas emissions through a case study of a product chosen to represent the retail process. We conclude that e-commerce has lower energy use and GHG emissions for our case study.

Uncertainty and Variability in Product Carbon Footprinting

Recent years have seen increasing interest in life cycle greenhouse gas emissions accounting, also known as carbon footprinting, due to drivers such as transportation fuels policy and climate�?related eco�?labels, sometimes called carbon labels. However, it remains unclear whether applications of greenhouse gas accounting, such as carbon labels, are supportable given the level of precision that is possible with current methodology and data. The goal of this work is to further the understanding of quantitative uncertainty assessment in carbon footprinting through a case study of a rackmount electronic server. Production phase uncertainty was found to be moderate (±15%), though with a high likelihood of being significantly underestimated given the limitations in available data for assessing uncertainty associated with temporal variability and technological specificity. Individual components or subassemblies showed varying levels of uncertainty due to differences in parameter uncertainty (i.e., agreement between data sets) and variability between production or use regions. The use phase displayed a considerably higher uncertainty (±50%) than production due to uncertainty in the useful lifetime of the server, variability in electricity mixes in different market regions, and use profile uncertainty. Overall model uncertainty was found to be ±35% for the whole life cycle, a substantial amount given that the method is already being used to set policy and make comparative environmental product declarations. Future work should continue to combine the increasing volume of available data to ensure consistency and maximize the credibility of the methods of life cycle assessment (LCA) and carbon footprinting. However, for some energy�?using products it may make more sense to increase focus on energy efficiency and use phase emissions reductions rather than attempting to quantify and reduce the uncertainty of the relatively small production phase.

Carbon footprinting upstream supply chain for electronics manufacturing and computer services

Corporations and institutions, including the electronics manufacturing and computer services sectors have become concerned with their impacts on climate change and are participating in carbon footprint assessment and climate management discussions. Existing carbon footprint protocols classify carbon footprint into tiered “Scopes”: direct emissions as “Scope 1”, emissions from direct purchased energy as “Scope 2”, and all other indirect emissions as optional “Scope 3.” Because Scopes 1 and 2 footprints are generally less than 25% of the total direct and upstream footprint for a vast majority of businesses, Scope 3 emissions should not be ignored as knowledge of them can help inform more holistic approaches to address life cycle footprint across the supply chain. This research uses input-output life cycle assessment methods to conduct a “scoping analysis” that characterizes the carbon footprint profiles of 8 electronics manufacturing and computer services sectors. The results show that there are significant variations in the portions of total analyzed footprint captured by each footprint Scope among this sector group. Most of the footprints for the electronics manufacturing sectors do not come from their Scope 1 emissions, but from the embodied emissions in the supplies of parts, components, chemicals, and materials. Purchases of food, air transportation, and hotel accommodation from employees traveling to customer locations are found to be the largest sources of upstream Scope 3 footprint for computer system design services sector. The results presented in this work are intended to inform footprinting entities and companies of the potential Scope 3 subcategories to focus their footprint efforts.