Reduction In Emission Intensity Research Articles

A Study on the Impact of Watershed Compensation Policies on Green Technology Innovation Ecosystems

This study uses the implementation of the watershed compensation policy as a quasi-natural experiment and selects a sample of 53 cities located within the four major watersheds from 2005 to 2022. By employing a staggered difference-in-differences model and a synthetic control difference-in-differences model, the study investigates how watershed compensation policies influence green technology innovation ecosystems and delves into the underlying mechanisms that are responsible for these impacts. The research reveals the following findings: (1) The introduction of the watershed compensation policy markedly boosts the development of green technology innovation ecosystems in the pilot cities, and this finding remains consistent following a series of robustness checks. (2) An analysis of the mechanisms indicates that the watershed compensation policy exerts its impact on the advancement of green technology innovation ecosystems through a reduction in carbon emission intensity and the enhancement of wastewater treatment efficiency. (3) The influence of the watershed compensation policy on green technology innovation ecosystems varies according to the level of public financial expenditure and labor productivity. This research offers a factual foundation for comprehending the effects of watershed compensation policies on the innovation of green technologies within China.

Different technology packages for aluminium smelters worldwide to deliver the 1.5 °C target

Production of aluminium, one of the most energy-intensive metals, is challenging for mitigation efforts. Regional mitigation strategies often neglect the emissions patterns of individual smelters and fail to guide aluminium producers’ efforts to reduce GHG emissions. Here we build a global aluminium GHG emissions inventory (CEADs-AGE), which includes 249 aluminium smelters, representing 98% of global primary aluminium production and 280 associated fossil fuel-based captive power units. We find, despite the installation of more efficient and higher amperage cells, that the share of aluminium production powered by fossil fuel-based captive power units increased from 37% to 49% between 2012 and 2021. Retiring fossil fuel-based captive power plants 10 years ahead of schedule could reduce emissions intensity by 5.0–10.5 tCO2e per tonne of aluminium for dependent smelters. At least 18% of smelting capacity by 2040 and 67% by 2050 must be retrofitted with inert anode technology to achieve net-zero targets.

Unintended consequences: market integration and enterprise carbon emissions ——based on the analytical perspective of county-to-district reform

ABSTRACT The county-to-district reform, as an important measure to break down administrative barriers between cities and counties and promote market integration, raises the question of whether it influences enterprise carbon emissions behaviour. By utilising data from 1992 to 2019 and matching it with patent data for Chinese listed companies, this paper examines the impact of the county-to-district reform on enterprise carbon emissions. The findings show that the reform accelerates market integration, facilitates the free flow of production factors, thus expanding the scale of enterprise production and increasing total carbon dioxide emissions from enterprises. Meanwhile, this process alleviates financing constraints for enterprises and increases the proportion of research and development investment on one hand; on the other hand, the reform intensifies market competition, thereby improving enterprise productivity. Ultimately, this leads to a reduction in overall carbon emission intensity. This phenomenon is particularly evident in non-state-owned enterprises, non-carbon trading pilot regions, northern regions, and small and medium-sized enterprises. This paper explores the impact of changes in China’s government power structure on enterprise carbon emissions behaviour, adding to the research on the role of micro-level enterprises in carbon reduction during the county-to-district reform process.

The carbon cost of impaired welfare on sheep farms.

In the face of global climate threats, farm and land-management decisions must balance climate concerns with profitability, animal welfare, and ecosystem health. However, few comprehensive studies have quantified the relationship between animal welfare and greenhouse gas (GHG) emissions, and no study focuses specifically on sheep farms. The present study aims to quantify the effects of impaired welfare on GHG emissions for common welfare challenges faced in UK lowland (L) and hill (H) sheep farming systems. Two case study research farms in Scotland, representative of high welfare conditions, were used as baselines for semi-intensive L and extensive H systems. In this study, "high welfare conditions" are defined as situations where animals have access to adequate feeding, suitable housing, good health, and opportunities to express natural behaviours. From each high-welfare baseline, scenarios representing common levels of impaired welfare conditions were modelled, using parameters retrieved from the published literature. The selected poor-welfare scenarios included lameness, gastrointestinal nematodes, blowfly strike, liver fluke, inadequate shelter provision, inadequate feeding during lamb growth and late gestation, and high lamb mortality rate. GHG emissions were estimated "from-cradle-to-farm-gate" using Agrecalc ©, a Life Cycle Assessment tool for the agricultural sector. Total GHG emissions and emission intensities (EI) in kg of CO2 equivalent per kg live weight were compared across the baseline and the scenarios. Gross farm emissions and product-level EIs demonstrated divergent patterns in response to impaired welfare. Most impaired welfare scenarios led to a slight decrease in total farm emissions (0.03-3%), with a few exceptions. On the other hand, EI increased across all impaired welfare scenarios relative to the baseline, because meat production decreased by 1.3-16.6% across all impaired welfare scenarios, reducing resource use efficiency. Lameness was identified as particularly impactful, resulting in 18 and 10% increases in EI on H and L farms, respectively. This was primarily due to the high lamb mortality associated with lameness in published studies. Inadequate shelter provision was associated with an 8-15% increase in EI. Scenarios related to ineffective parasite control contributed to an EI increase ranging from 1 to 13%, while inadequate feeding management caused a 3-4% increase in EI. This study highlights the potential for reducing emission intensity through system-specific interventions, emphasising the importance of integrating animal welfare into GHG mitigation strategies.

Climate Risks and Economic Consequences of Rising Global CO2 Emissions in Aviation, Shipping, and Heavy-Duty Transport

This study examines methods to lessen the environmental consequences of global CO2 emissions from the hard-to-abate transport sector. The paper analyzed historical and projected trends in global CO2 emissions from the hard-to-abate transport industry under two scenarios: the stated policy scenario (STEPS) and the announced pledged scenario (APS). The study covered the historical period from 2010 to 2022 and projected emissions up to 2050. The analysis revealed that the compound annual growth rate (CAAGR) of STEP exceeded that of APS in 2030 and 2050 for challenging emissions from heavy- duty vehicles, aircraft, and shipping when compared to the baseline year of 2022. The aviation industry has a higher CAAGR of 5.3% and 2.5% for 2030 and 2050, respectively, compared to heavy-duty vehicles at 1.6% and 0.9% for 2030 and 2050, respectively, and shipping at 0.7% and 0.9% for 2030 and 2050, respectively, under STEPS. Under the APS scenario, shipping showed a negative CAAGR of -0.8% and -2.8% for 2030 and 2050, respectively, and 0.4% and -1.8% for 2030 and 2050, respectively, for heavy-duty trucks. In comparison, the aviation industry had CAAGRs of 4.5% and 0.8% for 2030 and 2050, respectively. The data shows that the aviation industry is expected to see a far greater CAAGR in emissions than heavy-duty vehicles and shipping in both STEPS and APS scenarios. Targeted efforts are necessary to mitigate the environmental effects of air travel in the upcoming decades. The paper also examined 56 publicly traded international transportation companies and their corresponding carbon emission targets. Only seven companies, or 12.5%, have established goals for reducing emissions from 2023 to 2050; 10 companies, accounting for 17.9%, have committed to achieving carbon neutrality by 2040 to 2060; five corporations, representing 8.9%, have set targets for reducing emission intensity from 2025 to 2034; and 34 global corporations, making up 60.7%, have committed to achieving net zero emissions between 2040 and 2050. Despite some progress in setting emission reduction targets in the air travel industry, many companies still need to set carbon footprint reduction goals.

Estimating the marginal effects of plot-scale socio-economic and spatial morphological factors on carbon emissions from non-linear perspective

The paper adopts a micro-level, plot-scale approach to propose a carbon emissions calculation method. Additionally, it develops an indicator system to quantitatively assess the non-linear impact of socio-economic and spatial morphological factors across different land uses on carbon emissions intensity (CEI) at the plot-scale. The results indicate that the four key factors influencing CEI are economic level, population density, building coverage rate, and fractal dimension, which affect resident activity intensity and building energy efficiency. Our findings reveal three marginal effects of these factors on emissions:①Threshold Plateau Effect: Beyond certain levels, increases in economic level and population density have minimal impact on emissions, indicating a plateau. ②Association Effect: Taller buildings lead to higher per-area activity and emissions, suggesting that controlling building height can reduce emission intensity. ③Stepwise Increase Effect: CEI in phases with increased road and transportation infrastructure density. The insights from these effects can inform urban planning strategies, enabling planners to design and implement development policies that effectively promote low-carbon urban growth.

Optical performance and luminescence properties of Dy3+-doped LaMgB5O10 phosphors

Despite significant advancements in borate-based phosphors, improving luminescent efficiency and thermal stability, particularly at high temperatures, remains a persistent challenge. In this study, Dy3+-doped LaMgB5O10 (LMBO) phosphors were synthesized and characterized for their photoluminescent properties to address these issues. Under 344 nm excitation, the Dy3+-activated LMBO phosphors exhibited strong luminescence with characteristic peaks at 482 nm (blue), 578 nm (yellow), and 663 nm (red), corresponding to specific Dy3+ transitions. Optimal luminescence was achieved at a doping level of 2 wt% Dy3+, beyond which quenching effects reduced emission intensity. The critical quenching distance (Rc) was estimated at 24.66 Å, indicating predominant non-radiative energy transfer. Moreover, thermal quenching was reduced, with the activation energy for thermal quenching determined to be 0.1975 eV, demonstrating that the material can maintain reasonable luminescence efficiency at elevated temperatures. Time-resolved photoluminescence spectroscopy revealed multi-exponential decay behavior, indicating the presence of multiple decay processes. The average luminescence lifetimes were calculated as 632 µs for the 2 wt% Dy3+ sample and 539 µs for the 3 wt% Dy3+ sample, with a clear concentration quenching effect observed at higher dopant levels. Colorimetric analysis in the CIE 1931 color space revealed a shift toward yellow with increasing Dy3+ concentration, achieving a correlated color temperature (CCT) of 6595 K at 2 wt% Dy3+. This shift supports the material’s potential for photonic and lighting applications. These findings highlight a significant advancement in addressing the thermal stability issue in phosphor materials, making Dy3+-doped LMBO phosphors promising candidates for advanced photonic technologies.

Comparative analysis of carbon emission reduction policies in China's manufacturing and transportation sectors

This study evaluates China's environmental policies, specifically the increase of carbon emission tax rates and the reduction of carbon emission intensity, by developing a New Keynesian Dynamic Stochastic General Equilibrium (NK-DSGE) model that incorporates energy consumption and carbon emissions. The production sector is segmented into manufacturing, non-manufacturing, and transportation, with transportation services acting as inputs for both manufacturing and non-manufacturing firms. We construct four cases within two scenarios, each characterized by distinct targets and policies. After calibrating and estimating the relevant parameters, we compare carbon reduction outcomes and economic fluctuations across the two scenarios. Our findings indicate that when targeting the same carbon emission tax rate increase or carbon emission intensity ratio reduction, policies that increase the carbon emission tax rate or reduce carbon emission intensity implemented in the manufacturing sector achieve greater carbon emission reductions compared to the same polices implemented in the transportation sector. Meanwhile, compared to the latter case, output experienced a greater decline, and inflation exhibited a more substantial increase in the former case. However, when the quantities of carbon emission reductions are approximately the same in the first quarter, policies that increase the carbon emission tax rate or reduce carbon emission intensity enacted in the transportation sector demonstrate superior performance relative to the same polices implemented in the manufacturing sector. This leads to smaller final output reductions and milder inflation increases. In summary, for equivalent levels of carbon emission reductions, policies implemented in the transportation sector yield more favorable economic outcomes than those applied in the manufacturing sector.

The Impact of High-Standard Scenic Areas Construction on County-Level Carbon Emissions and Its Spatial Spillover Effects: Evidence from a Quasi-Natural Experiment

This study investigated for the first time the tourism–carbon emissions nexus based on the destination construction perspective, using the China’s national scenic areas (CNSA) construction as a vehicle for concretization. A multi-source county panel dataset of 29,628 samples was constructed. The staggered Difference-in-Differences (DID) model and spatial DID model were further formulated. The findings show that: (1) the CNSA resulted in a 0.1024% reduction in carbon emission intensity (CEI) in treatment counties relative to non-treatment counties, and although the effect exhibits a delay, it persists and intensifies over time; (2) our heterogeneity results indicate that the inhibiting effect is significantly more pronounced in the western, eastern, and county subsamples; and (3) the spatial DID analysis reveals that the CNSA exerts a negative spatial spillover effect on CEI. This work enhances comprehension of the tourism–carbon emissions nexus, with implications for advancing regional carbon emission reduction policy strategies.

Exploring the role of trade credit in facilitating low-carbon development: Insights from Chinese enterprises

As the world's largest emitter of carbon, China is proactively addressing climate change in a responsible manner. The country has set an ambitious goal of achieving the most significant reduction in carbon emission intensity globally within approximately 30 years. In light of the transition to a new low-carbon environment, it is imperative that Chinese enterprises assume a more proactive role in embracing carbon neutrality as a social responsibility. The question of how to supplement the green transformation funds that have not yet been covered by green finance has become a significant issue for Chinese enterprises seeking to achieve sustainable development and promote high-quality development. This study employs hand-collected data on companies' carbon emissions from 2018 to 2023, using the fixed effects model to conduct a comprehensive investigation of the role of trade credit embedded within the supply chain in driving the green evolution of Chinese companies and reducing their carbon dioxide emissions. The findings demonstrate that trade credit has a significant impact on reducing CO2 emissions for Chinese businesses while also enhancing their commitment to adopting greener practices, their capacity for investing in green transformation, and the quality of their green outputs. The results of the heterogeneity analysis indicate that the acquisition of trade credit exerts a more pronounced suppressive influence on carbon emissions for heavy-polluting enterprises, non-state-owned enterprises, low-supplier concentration enterprises, and maturity stage enterprises. Similarly, the supply of trade credit notably curtails the carbon emissions for non-heavy polluting enterprises, non-state-owned enterprises, low-medium customer concentration enterprises, and maturity stage enterprises. The empirical findings of this study contribute to reconciling the substantial dilemma between corporate goals for energy conservation, emissions reduction, and production growth. This research offers key insights to support businesses in achieving a gentle transition towards energy efficiency and reduced carbon footprint in line with the overarching trend of sustainable and low-carbon development.

Toward circular economy: Implementing circular economy strategies to reduce carbon emissions in Chinese cities

AbstractTo avert the worst impacts of climate change, greenhouse gas emissions must be reduced by 45% by 2030 and reach net zero by 2050, as outlined in the Paris Agreement. The circular economy (CE) is expected to play a key role in achieving this goal by changing consumption and production patterns. However, the actual impact of CE on reducing carbon emission intensity remains unclear, especially in developing countries. This paper examines the effect of CE‐associated actions on reducing carbon emission intensity in Chinese cities, utilizing CE pilot policy experimentation. We employ difference‐in‐differences (DID) methods with data from 282 cities spanning 2002 to 2012 to analyze the average treatment effect of CE actions. Our results show a significant reduction in carbon emission intensity in CE pilot cities compared to non‐pilot cities after the implementation of CE practices. Moreover, our estimates indicate that the carbon reduction effect strengthens over time, driven by the improvements in green innovation capacity and industrial structure upgrades. The effectiveness of CE varies across city types, with more pronounced impacts observed in economically underdeveloped and resource‐based cities. However, while CE practices reduce carbon emission intensity in pilot cities, significant spatial spillover effects increase emissions in neighboring cities. In conclusion, our findings underscore both the effectiveness and complexity of the CE pilot policy in reducing carbon emission intensity in Chinese cities.

Investors reward countries for participating in climate agreements

International climate agreements are one of the best-known approaches to coordinating climate actions among governments but face a free-rider problem, where individual governments lack sufficient incentives to reduce emissions. This study examines the role of investors in providing rewards to governments through sovereign bond yields to encourage climate cooperation and reduce emission intensity. Using a difference-in-differences method, this study examines how sovereign bond yields change around the Kyoto Protocol and the Paris Agreement. The findings show that investors reward governments committed to reducing greenhouse gas emissions with a 4 to 5 basis point decrease in sovereign bond yields. This suggests that investors better compensate countries making significant commitments to climate agreements, helping mitigate the free-rider problem and encouraging effective climate action.

Agricultural Productivity and Climate Mitigation

Agriculture will play a central role in meeting greenhouse gas (GHG) emission targets, as the sector currently contributes ∼22% of global emissions. Because emissions are directly tied to resources employed in farm production, such as land, fertilizer, and ruminant animals, the productivity of input use tends to be inversely related to emissions intensity. We review evidence on how productivity gains in agriculture have contributed to historical changes in emissions, how they affect land use emissions both locally and globally, and how investments in research and development (R&D) affect productivity and therefore emissions. The world average agricultural emissions intensity fell by more than half since 1990, with a strong correlation between a region's agricultural productivity growth and reduction in emissions intensity. Additional investment in agricultural R&D offers an opportunity for cost-effective (<US$30 per ton carbon dioxide) and large-scale emissions reductions. Innovations that target specific commodities or inputs could even further reduce the cost of climate mitigation in agriculture.

Representative CO2 emissions pathways for China's provinces toward carbon neutrality under the Paris Agreement's 2 °C target

China has committed to achieving carbon neutrality by 2060. It is essential to develop representative CO2 emissions pathways at the provincial level that align with the national target to facilitate effective policy implementation and scientific research. To address inconsistencies between provincial aggregate emissions and national estimates, this study compares the 2021 CO2 emissions estimates of China's provinces from the bottom‒up emissions factor method and the top‒down atmospheric CO2 concentration inversion method. We find that these methods yield comparable results for the emissions from energy combustion and industrial processes at the provincial level. Based on a review of existing research on CO2 pathways for China's provinces, we propose a set of representative pathways for China's provinces. These pathways align with past practices of allocating national emissions intensity reduction targets to provinces and are consistent with the national Tsinghua‒CMA pathway. The proposed pathways require provinces to sequentially peak their emissions by 2030, followed by rapid emissions reduction. Compared to a reference scenario without the carbon neutrality target, these pathways would incur an estimated cumulative GDP loss of about 1% between 2020 and 2060. However, there are notable regional variations, with some regions in the northwest potentially experiencing higher economic growth due to the availability of high-quality low-carbon resources. We recommend that China enhance provincial-level CO2 emissions accounting by cross-validating bottom‒up and top‒down methods. Additionally, careful consideration should be given to aligning provincial targets with national and global commitments when updating pathways toward carbon neutrality.

The green bonus of tax incentives: Evidence from China

Using a novel dataset covering over one million firm-level energy consumption entries from 2007-2016, we employ a difference-in-differences approach to estimate the causal effect of tax incentives on carbon emission intensity by exploiting China’s staggered implementation of accelerated depreciation policies for fixed assets in 2014 and 2015. We find that the accelerated depreciation policy leads to a significant 9.19% reduction in carbon emission intensity, equivalent to 0.11 tons of carbon emissions per 10,000 RMB of industrial value added. The policy effect is more pronounced for large firms, those with medium-term assets, and in regions with greater market integration and industrial agglomeration. Our firm-level analysis reveals that the policy reduces energy consumption, promotes a shift towards a cleaner energy portfolio and increases R&D investments in abatement technologies, as well as climate-friendly innovations. The above results show high consistency with verification at the aggregation level using satellite-based observations. Our findings highlight the potential of well-designed fiscal policies to contribute to global climate action efforts in developing economies.

Optimising Nitrogen Fertilisation in a Potato–Oat Rotation and Implications for Nitrous Oxide Emissions in Volcanic Soils

High nitrogen (N) fertiliser rates are usually applied to increase agricultural yields, leading to high nitrous oxide (N2O) emissions. This is a greenhouse gas that contributes to climate change and depletes the ozone layer. This study aimed to optimise N use efficiency and quantify N2O emission factors (EF1) by measuring the effect of N rates on the yield of a potato-cover crop rotation, apparent N use efficiency (NUE) and N2O emissions. The two-year experiment was carried out on volcanic soils (1.6% carbon, 1.4% N) in southern Chile (40°52′ S, 73°03′ W). Three N application rates were evaluated (80, 150 and 300 kg N ha−1), 35% of which was applied at the planting stage (granular) and 65% at the tubering stage. A control treatment with no N addition was also included. Reducing N fertilisation to 80 kg N ha−1 increased NUE by three times, reduced N2O-N emissions by 33% and reduced emission intensity by 27% without a detrimental impact on crop yield and marketable tuber calibre. No significant difference (p < 0.05) was observed in the N2O emission factor (EF1) because of a low rainfall year. The results suggest that in rainfed agriculture systems, N fertiliser application can be significantly reduced without sacrificing potato yield, favouring the economic and environmental sustainability of potato production.

358 The effect of increasing dietary limestone concentration on growth performance, gas flux, and carcass characteristics in finishing beef cattle

Abstract Reducing methane (CH4) emissions from beef cattle is desirable as CH4 is a greenhouse gas that represents an energetic loss from the production system. Limestone is commonly fed to cattle as a source of calcium but may also act as a rumen buffer and decrease CH4 emissions by limiting hydrogen availability for methanogenesis. The objective of this experiment was to determine if diet limestone concentration influences growth performance, gas flux, and carcass characteristics in finishing beef cattle. Yearling steers [n = 16; initial body weight (BW) 619 ± 34 kg] were stratified by BW and randomly assigned to 1 of 2 isocaloric and isonitrogenous dietary treatments in a completely randomized design where limestone was included at 1.3% (1X) or 2.6% (2X) of diet dry matter (DM). Finishing diets were formulated to contain 0.43 or 0.96% DM as Ca and were fed ad libitum using automated cattle feeders (SmartFeed Pro; C-Lock Inc.; Rapid City, SD) in a single pen for the final 37 d of finishing. Body weights were measured on d -1, 0, 36, and 37. An automated head chamber system (GreenFeed; C-Lock Inc.) was used to measure gas flux. Analysis of variance was conducted using JMP Pro 17 to determine the fixed effect of treatment with individual animal as the experimental unit. Statistical significance was defined as P ≤ 0.05 with a tendency defined as 0.05 < P ≤ 0.10. Increasing the dietary limestone concentration from 1.3 to 2.6% of DM did not influence DM intake, but numerically increased final shrunk BW (P = 0.68) and hot carcass weight (P = 0.75) and increased average daily gain (ADG; P = 0.02) and gain to feed ratio (G:F) by approximately 12%. Cattle fed the 2X diet tended to have 6.5% greater ribeye area (P = 0.09), but similar USDA yield grade, backfat thickness, and dressing percentage (P ≥ 0.34) when compared with cattle fed the 1X diet. Daily CO2 and CH4 emissions, daily O2 consumption, CH4 yield, and respiratory quotient were unaffected by treatment (P ≥ 0.47). The improvement in ADG resulted in a tendency for CH4 emission intensity to be decreased by 9.1% (P = 0.09) when the concentration of limestone was 2.6% of dietary DM. While increasing dietary limestone concentration from 1.3 to 2.6% of diet DM did not influence absolute daily CH4 emissions, it increased ADG through an improvement in feed efficiency, which translated to a tendency for a reduction in CH4 emission intensity. These preliminary data suggest that there may be a benefit to feeding limestone or calcium at levels greater than currently recommended by the NASEM (2016). Future research should focus on determining optimum dietary limestone or calcium levels for finishing cattle.

Well-to-Wheel emissions of electric vehicles in Türkiye and emission mitigation by renewable penetration

Automotive technology is currently on the verge of transitioning to electric vehicles, and both the impact of these vehicles on electricity consumption and their environmental performance are the focus of significant interest. In this paper, the emission impacts based on the use of electric vehicles are analyzed using the Well-to-Wheel methodology. In order to evaluate electric vehicle emissions, emissions based on electricity generation and consumption are first determined. Emission intensities are found in gCO2e/kWh for electricity consumption and gCO2e/km for battery electric vehicles. Well-to-wheel emissions are found 172.2 and 89.1 gCO2e/km for conventional and electric vehicles, respectively. With the renewable penetration in electricity generation, the emission intensity will be lower, which means that the emissions of electric vehicles will be further reduced. Thus, a renewable energy supported charging station is simulated and it is shown that emission intensities can be reduced by 60 %. It is concluded that Türkiye should focus primarily on renewable energy sources and then nuclear energy in order to meet the increasing electricity demand and reduce emission intensities.

Data-Driven Insights into the Contamination of Polycyclic Aromatic Hydrocarbons in Marine Bays.

The synthesis of polycyclic aromatic hydrocarbon (PAH) data allows us to quantify and gain insights into the spatiotemporal dynamics of PAH contamination in marine bays. Here, a data synthesis framework was developed to understand data-driven insights into the spatiotemporal levels, compositional profiles, and potential sources of PAHs in water and sediment of marine bays. PAHs were detected in 69 bays worldwide, with contamination hotspots located in Asian bays. PAH concentrations in pre-2000 were significantly lower than those in the 2000s and post-2010, while the dominant species in water and sediment were 2-3 ring and 4-6 ring PAHs, respectively. The composition patterns of PAHs included 2-3 ring, 3-5 ring, and 4-5 ring dominant categories, but no significant distance decay relationship was found in the composition similarity due to international energy trade. Temporal dynamic patterns of concentrations included Descending-, Ascending-, and Inverted V-type, whereas over longer time spans, the pattern is more similar to the Inverted V-type owing to the reductions in emission intensity. PAHs were derived from both petrogenic and pyrolytic sources, with combustion from both coal and petroleum being the dominant source. These data-driven discoveries provide quantitative insights into the spatiotemporal patterns in the concentration and composition of PAHs, contributing to the mitigation of PAH contamination.

Projects as Vectors of Change: A Transition Toward Net-Zero Sociotechnical Systems

Projects are essential for the net-zero transition, yet the project studies literature largely ignores net-zero transition and net-zero projects. We argue that projects are vectors of change enabling the transition toward net-zero sociotechnical systems. Leveraging a systematic literature review, we identify four types of net-zero projects: (1) new assets; (2) upgrade assets; (3) behavioral intervention; and (4) Research, Development, and Demonstration (RDD). We present how “net-zero projects” can enable the transition of sociotechnical systems toward net-zero, reducing emission intensity or quantity. Finally, we underline the heterogeneity of net-zero projects in terms of complexity, barriers, benefits realization time span, and complementarities.