A multiyear assessment of air quality benefits from China’s emerging shale gas revolution: Urumqi as a case study

China is seeking to unlock its shale gas in order to curb its notorious urban air pollution, but robust assessment of the impact on PM2.5 pollution of replacing coal with natural gas for winter heating is lacking. Here, using a whole-city heating energy shift opportunity offered by substantial reductions in coal combustion during the heating periods in Urumqi, northwest China, we conducted a four-year study to reveal the impact of replacing coal with natural gas on the mass concentrations and chemical components of PM2.5. We found a significant decline in PM2.5, major soluble ions and metal elements in PM2.5 in January of 2013 and 2014 compared with the same periods in 2012 and 2011, reflecting the positive effects on air quality of using natural gas as a heating fuel throughout the city. This occurred following complete replacement with natural gas for heating energy in October 2012. The weather conditions during winter did not show any significant variation over the four years of the study. Our results indicate that China and other developing nations will benefit greatly from a change in energy source, that is, increasing the contribution of either natural gas or shale gas to total energy consumption with a concomitant reduction in coal consumption

Global GHG Emissions Driven by the U.S. Household Consumption from 1995-2009

In the Paris Agreement, 195 countries are committed to making joint efforts to limit global temperature increase below 2℃ this century. Countries are motivated to take voluntary climate actions, but few studies have provided systematical analysis to inform households about their carbon footprints. This study analyzed global GHG emissions driven by U.S. household consumption between 1995 and 2009. Multi-Regional Input-Output (MRIO) method is applied to analyze global trade networks. Consumer Expenditure Survey is linked with the trade networks to provide details on the emission profile of U.S. households. The research finds that total GHG emissions driven by U.S. households ranged from 4.8 to 6.2 billion tCO2eq/yr with an increasing trajectory over time. Housing and transportation contributed nearly 70% of the total domestic GHG emissions. Emissions overseas increased from 13% to over 20% of the total emissions in the studied period, mostly embodied in manufactured products including clothing, electronics and machinery supplies. Household carbon footprint amounted to 18.6-20.8 tCO2eq/cap∙yr-1 , ranging from 11.5 to 29.6 tCO2eq/cap∙yr-1 among rich and poor households. This study implicates that trade policies could be applied to green the global supply chain, and people with higher income should take more climate responsibility to achieve the goal of sustainable production and consumption.Master of ScienceSchool for Environment and SustainabilityUniversity of Michiganhttps://deepblue.lib.umich.edu/bitstream/2027.42/143186/1/Song_Kaihui_Thesis.pd

Household carbon inequality in the U.S

Household carbon emissions are mainly affected by income and other key demographic factors. Understanding the contribution of these factors can inform climate responsibilities and potential demand side climate mitigation strategies. By linking US consumer expenditure survey data with a nested national within a global multi-regional input-output model, this study estimates consumption-based GHG emissions for 9 income groups and assesses the carbon inequality in the US for 2015. Our results show that the per capita carbon footprint (CF) of the highest income group (200 thousand USD per year) with 32.3 tons is about 2.6 times the per capita CF of the lowest income group

Assessing subnational climate action in G20 cities and regions: Progress and ambition

Cities and regional authorities play a crucial role in driving climate action to limit global warming to 1.5°C. Despite their critical importance, significant obstacles in data collection and variability in implementation complicate the assessment of their contributions. This study provides the largest analysis of climate efforts across more than 3,000 cities and 170 regions within the G20 nations, revealing a noticeable uptick in the adoption of medium- to long-term emissions reduction and net-zero targets post-2020. However, over 60% of these subnational entities are failing to meet their climate ambitions, with a larger percentage not achieving the reduction rates necessary to align with the 1.5°C goal. These findings underscore the pressing need for enhanced accountability mechanisms for subnational climate actions. Implementing standardized reporting and boosting transparency are pivotal steps to ensure that local and regional efforts substantively contribute to achieving both national and global climate objectives

Quantifying greenhouse gas emission risks from natural gas pipeline incidents

Natural gas pipelines are key energy infrastructures worldwide. Pipeline incidents frequently result in greenhouse gas (GHG) emissions that remain unaccounted for in carbon inventories. This study analyzed natural gas pipeline incidents in the United States, finding that such incidents released 14.71–18.20 million tCO2e during 2010–2021, representing an additional 2.67%–3.30% of total emissions. Presently, the US Environmental Protection Agency inventories record emissions during routine normal operations while excluding the incident-based releases. Regional patterns show that US Gulf Coast and South Central states have substantially higher emission risks than other regions. Pipeline age analysis reveals a non-monotonic risk pattern, with dual peaks driven by distinct failure mechanisms. Early-life pipelines (0–10 years) have elevated risks resulting from equipment failures, while long-life serviced pipelines experience degradation-related risks. The top 10% of incidents generate 57% of total emissions. Targeting the high-emitting incidents could reduce cumulative emissions by over 40%, highlighting substantial mitigation opportunities through improved monitoring and management strategy.<p/

Can U.S. multi-state climate mitigation agreements work? A perspective from embedded emission flows

Subnational and non-governmental actors are expected to provide important contributions to broader climate actions. A consistent and accurate quantification of their GHG emissions is an important prerequisite for the success of such efforts. However, emissions embodied in domestic and international supply chains, that can undermine the effectiveness of climate agreements, add challenges to the quantification of emissions originating from theconsumption of goods and services produced elsewhere. We examine emission transfers between the states that have joined the U.S. Climate Alliance (USCA) and others. Our results show that states pledging to curb emissions consistent with the Paris Agreement were responsible for approximately 40% of total U.S. territorial GHG emissions. However, when accounting for transferred emissions through international and interstate supply chains of the products they consume, the share of Alliance states increased to 52.4% of the national total GHG emissions. The consumption-based emissions for some Alliance states, such as Massachusetts and New York, could be more than 1.5 times higher than their production-based emissions. Our detailed sectoral analysis highlights the challenges facing such agreements to extend cooperation in the future for larger joint benefit given the potential for carbon leakage from member states implementing stricter environmental policies that could lead to higher emissions from non-member states. It is critical for these arrangements to pay close attention to transferred emissions

Scale, distribution and variations of global greenhouse gas emissions driven by U.S. households

The U.S. household consumption, a key engine for the global economy, has significant carbon footprints across the world. Understanding how the U.S. household consumption on specific goods or services drives global greenhouse gas (GHG) emissions is important to guide consumption-side strategies for climate mitigation. Here we examined global GHG emissions driven by the U.S. household consumption from 1995 to 2014 using an environmentally extended multi-regional input-output model and detailed U.S. consumer expenditure survey data. The results show that the annual carbon footprint of the U.S. households ranged from 17.7 to 20.6 tCO2eq/capita with an expanding proportion occurring overseas. Housing and transportation contributed 53–66% of the domestic carbon footprint. Overseas carbon footprint shows an overall increasing trajectory, from 16.4% of the total carbon footprint in 1995 to the peak of 20.4% in 2006. These findings provide valuable insights on the scale, distribution, and variations of the global GHG emissions driven by the U.S. household consumption for developing consumption-side strategies in the U.S. for climate mitigation.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150690/1/Scale, distribution and variations of global greenhouse gas emissions driven by U.S. households.pdfDescription of Scale, distribution and variations of global greenhouse gas emissions driven by U.S. households.pdf : Main articl

Phonon heat conduction across slippery interfaces in twisted graphite

Interlayer rotation in van der Waals (vdW) materials offers great potential for manipulating phonon dynamics and heat flow in advanced electronics with ever higher compactness and power density. However, despite extensive theoretical efforts in recent years, experimental measurements remain scarce especially due to the critical challenges of preparing single-crystalline twisted interfaces and probing interfacial thermal transport with sufficient resolution. Here, we exploited the intrinsic twisted interfaces in highly oriented pyrolytic graphite (HOPG). By developing novel experimental schemes based on microfabricated mesas, we managed to achieve simultaneous mechanical characterizations and thermal measurements. In particular, we pushed the HOPG mesas with a microprobe to identify and rotate single-crystalline intrinsic interfaces owing to their slippery nature as is well known in structural superlubricity. Remarkably, we observed over 30-fold suppression of thermal conductance for the slippery interfaces by using epitaxial graphite as a control. Nonetheless, the interfacial conductance remains around 600 $\mathrm{MWm^{-2}K^{-1}}$ which surpasses the highest values for artificially stacked vdW structures by more than five times. Further, atomic simulations revealed the predominant role of the transverse acoustic phonons. Together, our findings highlight a general physical picture that directly correlates interfacial thermal transport with sliding resistance, and lay the foundation for twist-enabled thermal management which are particularly beneficial to twistronics and slidetronics

Greenhouse gas emissions from U.S. crude oil pipeline accidents:1968 to 2020

Abstract Crude oil pipelines are considered as the lifelines of energy industry. However, accidents of the pipelines can lead to severe public health and environmental concerns, in which greenhouse gas (GHG) emissions, primarily methane, are frequently overlooked. While previous studies examined fugitive emissions in normal operation of crude oil pipelines, emissions resulting from accidents were typically managed separately and were therefore not included in the emission account of oil systems. To bridge this knowledge gap, we employed a bottom-up approach to conducted the first-ever inventory of GHG emissions resulting from crude oil pipeline accidents in the United States at the state level from 1968 to 2020, and leveraged Monte Carlo simulation to estimate the associated uncertainties. Our results reveal that GHG emissions from accidents in gathering pipelines (~720,000 tCO2e) exceed those from transmission pipelines (~290,000 tCO2e), although significantly more accidents have occurred in transmission pipelines (6883 cases) than gathering pipelines (773 cases). Texas accounted for over 40% of total accident-related GHG emissions nationwide. Our study contributes to enhanced accuracy of the GHG account associated with crude oil transport and implementing the data-driven climate mitigation strategies