An empirical analysis of the non-linear effects of natural gas, nuclear energy, renewable energy and ICT-Trade in leading CO2 emitter countries: Policy towards CO2 mitigation and economic sustainability

Achieving reliable energy supply and environment sustainability whereby mitigating CO₂ emissions and promoting sustainable development has become a global effort. Thus, the current study intends to verify the non-linear influence effects of natural gas, nuclear energy, renewable energy and information and communication technology trade on economic growth and carbon dioxide emission in ten leading CO₂ emitter countries from 20002016. The panel regression, such as pooled regression, model fixed effect, random effects, robust least squares and panel causation procedures are applied for panel data appraisal. The regression analysis results mention that nuclear energy, renewable energy, and Information and communication technology (ICT-trade) stimulate economic growth, whereas environmental results illustrate that renewable energy and ICT-trade contribute to eliminating CO₂ emissions. The causality findings indicate that renewable energy consumption and ICT trade cause economic growth as well as CO₂ emissions. Therefore, policymakers should invigorate to exploit renewable energy and achieve the benefits from the significant influence of economic growth and a clean environment through the potential of green ICT-trade.

A study of consumer behaviour towards food-waste in Ireland: Attitudes, quantities and global warming potentials

This study aimed to investigate consumer behaviour towards food waste in Ireland by analysing their attitudes and quantities of food waste generated. Global warming potential of the food waste generated weekly is then assessed. A total of 2115 participants from all over the Republic of Ireland contributed to the survey (of which 2062 were included in this research). Using factor and cluster analysis, two clusters of consumers were formed based on their attitudes towards food waste, and it was found that 62.56% of the sample were 'uncaring' consumers and 37.44% were 'caring' consumers. The uncaring consumers consisted of more young males and were relatively unphased by food waste and take minimal precautions to reduce food waste at all stages of consumption. In contrast, caring consumers consisted of older and female consumers and were deeply disturbed by food waste, taking all precautions to reduce food waste at every stage of consumption. Regarding food waste quantities, uncaring consumers produced on average, 0.74 kg of food waste weekly, accounting for 2.74 kg of CO₂ equivalent in global warming potential, whereas caring consumers produced only half this amount. Our results thus suggest that consumers attitudes towards food waste directly impact the food waste quantities they generate and consequently the global warming effects. However, in Ireland all consumer groups can benefit from more information about food waste and our study contributes by providing information that can inform strategic communication campaigns at policy or organisational level, to educates consumers about food waste and how they are contributing to global warming.

Investigating the impact of in situ soil organic matter degradation through porewater spectroscopic analyses on marsh edge erosion

Marsh edge erosion results in soil organic matter (SOM) loss from coastal wetlands and is differentially affected by wind waves, soil properties, and vegetation cover. The degradation of SOM may make the marsh edge susceptible to erosion. The objective of this study was to investigate the effect of in situ biogeochemical degradations of SOM on marsh edge erosion using porewater spectroscopic analyses. Edge erosion was monitored at 12 transects in one of the highly eroding coastal basins of Louisiana. A total of 36 cores were collected at different distances from the edge of the marsh. Porewater was extracted and analyzed for dissolved organic carbon (DOC) and spectroscopic indicators. The north and west side had greater erosion rates (102.38 ± 5.2 cm yr^-1) than east and south side (78.47 ± 3.3 cm yr^-1). However, the north and east side had greater DOC and refractory carbon but less microbial activity indicating SOM degradation alone did not correlate to edge erosion. The intersecting trend between erosion rate and SOM degradation among four sides of the island indicates the complex nature of edge erosion drivers. The estuarine bottom indicators suggest the eroded SOM is not reburied but rather degraded and emitted back into the atmosphere as CO₂, potentially contributing to global change. The coastlines projected to experience high sea-level rise in the coming century are vulnerable to losing a large amount of stored carbon in the absence of efficient mitigation measures.

The environmental footprint of China-Africa engagement: An analysis of the effect of China - Africa partnership on carbon emissions

China has strategically engaged with African countries through different routes. However, the growing presence of China in Africa has attracted a lot of praise and criticism. As a leader in smart technology, China may fill the technological gaps in Africa, which improve the environment. Conversely, China may be exploiting natural resources and rapidly deteriorating the environment. Therefore, in this paper, we examine the impact of different routes of the China-Africa relationship on the environment. Using Fully Modified Ordinary Least Square (FMOLS) model on data from 50 African countries, we find that different Chinese activities affect the environment differently. We find a positive relationship between construction revenue and carbon emission, suggesting that China's construction activities negatively affect the environment. Similarly, export increases carbon emission and harms the environment. However, we find a negative relationship between importation from China and carbon emissions, implying a positive environmental footprint by China in Africa. In the case of foreign direct, the results show that foreign direct investment improves the environment, and the relationship is stronger in non-resource countries. Given that most exports from Africa are natural resources, our results imply that African non-resources-rich countries are likely to benefit from China's large investment in cleaner energy in the long-run, especially after the construction of the infrastructures. Our findings highlight the potential environmental risks associated with the different routes of China partnership with African countries.

Long-term fate of rapidly eroding carbon stock soil profiles in coastal wetlands

Marsh edge erosion is one of the major causes of land and associated carbon loss in wetland-dominated coastlines. Assessing carbon stocks and understanding fate of eroding carbon is an essential component of wetland carbon budget. This study aims to understand the vertical soil carbon profile of an eroding marsh and potential mineralization of carbon in estuaries. Eleven soil cores (~2 m deep) were collected from the edge of four highly eroding marsh sites and three cores from the estuarine bottom (~50 cm deep). Cores were sectioned into 10-cm intervals and analyzed for total, labile and refractory carbon, carbon density, select enzyme and microbial activities, and organic and inorganic phosphorus forms. The total carbon, labile carbon, and carbon density increased with depth at all sites. The carbon density at 1-1.5 m deep (0.04 ± 0.003 g cm^-3) was significantly higher (p < 0.0001) than the top 1 m soil (0.032 ± 0.002 g cm^-3), indicating the need for considering deeper carbon profile for blue carbon stock assessment. The age of the carbon at the estuarine bottom was 388 ± 84 years before present (ybp) indicating the recently eroded wetland carbon is not reburied in the estuary. Significant anaerobic microbial activity was present at all the soil depths suggesting high potential of mineralization of eroded carbon in the aerobic estuarine water. The coastlines experiencing high relative sea-level rise at present or coastlines that are projecting high sea-level rise in the near future are susceptible to losing an enormous amount of previously sequestered carbon over a relatively short period of time.

Driving propensity and vehicle lifetime mileage: A quantile regression approach

This study aims to determine the relationship between motor vehicle lifetime and lifetime mileage, while considering drivers' propensity to drive and its effects on vehicle CO₂ emissions. To do this, we analyze the relationship between lifetime mileage and vehicle lifetime for two vehicle types; a hybrid and a gasoline vehicle. We also employ a quantile regression approach to estimate the effects of drivers' propensity to drive on lifetime mileage. By estimating the CO₂ emissions based on driver's propensity to drive, we analyze the effects of propensity to drive on vehicle CO₂ emissions. Our results show that, for drivers who drive longer distances, the rate of decrease in average mileage grows as the vehicle age increases. Further, the results of our analysis, which considers this decrease in mileage, show that the cumulative CO₂ emissions calculated under the assumption of uniform average annual mileage have been overestimated. The actual lifecycle CO₂ emissions for the Prius are therefore smaller than previously reported by the previous studies, leading us to conclude that the hybrid is a more environmentally friendly vehicle than previously thought. Those of the Premio as a conventional gasoline vehicle, however, is approximately twice that. We suggest that vehicle lifecycle assessments should take into account the annual decrease in mileage demonstrated in this study.

How energy service companies moderate the impact of industrialization and urbanization on carbon emissions in China?

Energy service companies (ESCOs) have emerged to carry out energy efficiency retrofit projects, playing an essential role in mitigating carbon dioxide (CO₂) emissions in China. However, it remains unclear how exactly ESCOs contribute to CO₂ mitigation during urbanization and industrialization. We conducted regression analyses on data collected in 29 provinces in China as the first case study to investigate the moderating effect of ESCOs in relationships between urbanization, industrialization, and CO₂ emissions. The results indicate that urbanization had a significantly negative influence on CO₂ emissions. In contrast, industrialization displayed a statistically significant positive impact on CO₂ emissions. ESCOs have a significant moderating effect on the relationship between industrialization, urbanization, and CO₂ emissions. The analysis also revealed that ESCOs have a better performance in areas with lower industrialization and greater urbanization. ESCOs may invest more in regions with limited ESCO activities and huge CO₂ emission reduction demand, while energy-saving technology innovation should be advocated in regions with sufficient ESCO activities.

Influence of malonic acid and manganese dioxide on humic substance formation and inhibition of CO2 release during composting

The aim of thisstudy was to explore the effects of malonic acid (MA), manganese dioxide (MnO₂), malonic acid combined with manganese dioxide (MA + MnO₂) additionon reducing CO₂ emission and promoting humic substance (HS) formation during composting. The result showed that the addition of MA and MnO₂ were an efficient way to reduce CO₂ emission. Meanwhile, the CO₂ emissions in the MA + MnO₂ treatment was 36.8% less than that of the CK, and the amount of humic acid (HA) produced in the MnO₂ treatment was 38.7% higher than that of the CK. Structural equation models demonstrated that the addition of exogenoussubstance promoted the conversion of amino acids and reducing sugars to HA. The addition of exogenous substances was the main reason for influencing the concentration of HA. In general, this research provided theoretical supports for the addition of exogenous substances to promote HA formation during composting.

Optimal design and exergy analysis of biomass-to-ethylene glycol process

Ethylene glycol production has been significantly augmented in recent years due to its various uses. However, conventional oil and coal-based ethylene glycol routes are forcing severe obstacles in production cost and pollutant emissions. Biomass is regarded as a potential contributor to cleaner and sustainable development of the energy sector. Herein, an efficient biomass-to-ethylene glycol (BtEG) process is firstly proposed and analyzed by the simulator, Aspen Plus software. Its key operational parameters are investigated and optimized after the validation of the established models and simulation results. Results show that the optimal oxygen/biomass ratio and temperature of biomass gasifier are 0.4 t/t and 1300 °C. The optimal reaction temperature, pressure, and H₂/DMO ratio of ethylene glycol synthesis reactor are 220 °C, 4.0 MPa, and 4.5 kmol/kmol, respectively. After conducting carbon and exergy analyses, it found that the carbon and exergy efficiencies of this process are calculated as 37.64% and 38.74%.

Energy consumption, economic expansion, and CO2 emission in the UK: The role of economic policy uncertainty

On the 23rd of June 2016, the United Kingdom voted to leave the EU, leading to months and years of economic policy uncertainties. Such uncertainties have not only characterized the UK but have become a center point for energy debate in recent times. Given the foregoing, this paper progresses to provide evidence on the role of Economic Policy Uncertainty in the Energy Consumption - Emission nexus in the UK. We use annual data spanning the period of 1985-2017 for the UK for CO₂ emissions in tons per capita (CO₂), real GDP (RGDP), energy use (EU), and economic policy uncertainty (EPU). The Autoregressive distributed lag model (ARDL) bound test is used to test the fitness of the model in the short and long term. Our model shows that EPU matters most in the short run, as it reduces the growth of CO₂ emissions, while prolonged use of EPU in the UK, exhibit controversial influence, where CO₂ emissions continue to rise. In addition, pairwise Granger causality shows a one-way causality running from energy use to CO₂ emissions, CO₂ emissions to economic policy uncertainty, and also from energy use to economic policy uncertainty. However, two-ways causality is found between real GDP and real GDP per capita. Overall, our results imply that EPU is likely to yield a positive effect on climate change for a short time, but continue dependent will, in the long run, create an unhealthy environment. We suggest that the UK government should consider implementing an additional long-run policy that will supplement the effort of EPU.

Is India on the right pathway to reduce CO2 emissions? Decomposing an enlarged Kaya identity using the LMDI method for the period 1990-2016

Nowadays, India is the third-largest CO₂ emitter and energy consumer in the world, and, it is soon expected to surpass China as the most populated country. Therefore, it is of great interest to analyse how India is developing its energy transition to a lower-carbon economy. This work analyses the evolution of the main driving forces of CO₂ emissions in India during the period 1990-2016 through the use of an enlarged version of the Kaya identity, which establishes a link between CO₂ emissions, types of energy sources (16), size of the economic sectors (3) and value of the Gross Domestic Product. India's CO₂ emissions increased by 276% in the period under study, due to the rapid economic growth of India, which has been the dominating driving force contributing to the increase in CO₂ emissions by 241%, while the energy intensity has been the main one reducing them by approximately -47%. So far, the use of coal has supported the rapid economic growth and the contribution of renewable energy, although significant, is still short compared to the total amount of energy employed. Remarkably, the estimated value of the emission intensity for 2020 supposes a 26% reduction concerning the value in 2005. According to this result, India is on the right pathway to fulfil its Nationally Determined Contribution but not to reduce its net CO₂ emissions.

The success of the fertilization and early larval development of the tropical sea urchin Echinometra lucunter (Echinodermata: Echinoidea) is affected by the pH decrease and temperature increase

The decrease in the pH of oceans and the increase in their temperature are the two main problems observed in the marine ecosystems due to the increasing emission of CO₂ in the atmosphere. Both conditions can affect the ecological processes of reproduction, recruitment and survival of the marine biota. Thus, the objective of the present study was to evaluate the effects of pH decrease and temperature increase of seawater on the fertilization success and embryo-larval development of a species of tropical sea urchin. For this purpose, fertilization success (gametes) and embryo-larval development rate were determined by exposing gametes and embryos to decreasing pH values (8.0 (control), 7.7, and 7.4) and increasing temperatures (26 (control), 28, 30, 34, and 38 °C). These conditions were tested associated with each other (in synergy). The gamete test was sensitive to all investigated scenarios, the fertilization success was significantly reduced in the conditions of increased temperature (28, 30, 34, and 38 °C) associated with the ideal pH (pH 8.0) and the conditions of reduced pH (pH 7.7, and 7.4), remaining unchanged only in the ideal condition (pH 8.0 + 26 °C). However, the embryo test displayed enhanced sensitivity in the scenarios of temperature increase (28, 30, 34, and 38 °C) associated with pH decrease conditions. A significantly reduction of 29%, 23% and 10% was observed in all tested pH values at 38 °C, when compared to the control group (80%, 79.5% and 63%, respectively). Therefore, the present study suggests that the occurrence of both scenarios may have a significant impact, in the coming years, on the population of Echinometra lucunter.

Impact of biochar on greenhouse gas emissions and soil carbon sequestration in corn grown under drip irrigation with mulching

Biochar is widely used as a soil amendment to challenge climate change through restraining greenhouse gas production and increasing soil C sink in cropland soils, yet its effect was not studied well under drip irrigation with mulch. A two-year field experiment was conducted to investigate the impact of corn residue-derived biochar amendments on greenhouse gases (GHG), soil organic carbon (SOC), and global warming potential (GWP) on sandy loam soil in Inner Mongolia, China. Biochar application rates of 0 (B0, control), 15 (B15), 30 (B30), and 45 (B45) t ha^-1 were broadcasted onto the soil surface, and then mixed into 30-cm soil depth at the first crop growing season to a film-mulched and drip-irrigated corn production. Soil emissions of CO₂, N₂O, and CH₄ were measured using a closed static chamber approach. Compared to control plots, biochar amendments reduced total CO₂ emission by 18-25% at the first growing season, and 19-41% at the second growing season. The highest and lowest CH₄ emissions were from B45 and B15 in the first year, and B45 and B30 in the second year, respectively. Relative to the control, B15 and B30 reduced CH₄ emission by 124% and 132% as averaged over 2-yr. With biochar amendments, total N₂O emission was decreased by 71-110% and 39-47% in the first and second year. Among these biochar amendments, B30 was the best amendment limiting the GWP of N₂O and CH₄ in any of the two years. B30 and B45 significantly increased SOC sequestration in the top 15-cm depth by 19% and 37% in the first growing season, respectively, and by 12% and 15% in the second growing season. Biochar amendment B30 also significantly increased corn yields. Biochar shows the greatest potential to mitigate greenhouse gas emissions and increase soil C sequestration. The greatest reductions with biochar application 30 t ha^-1 in corn.

Immobilization of hazardous municipal solid waste incineration fly ash by novel alternative binders derived from cementitious waste

This work aims to immobilize hazardous municipal solid waste incineration fly ash (IFA) using alternative binders recycled from cementitious waste (CW) that was dehydrated. The dehydration temperature of CW applied was 200 °C, 500 °C and 800 °C, and the resulted binder was labelled as DCW2, DCW5 and DCW8, respectively. Thermal treatment increased the rehydration capacity of DCWs. Higher temperatures at 500 °C) can increase the amount of dehydrated phases, and contribute to a higher 28-day strength of DCW pastes. The DCW5 paste had the highest 28-day strength which was 18.74 MPa. The dicalcium silicate phase can be formed in DCW8, which resulted in its slow strength development and a lower 28-day strength compared to the DCW5 paste (about 50 % lower). Chloride contained in IFA can take part in the DCW hydration and contribute to the strength development of the binder-IFA pastes. The use of DCWs as binders had better immobilization efficiency of Pb compared to OPC. Furthermore, the CO₂ emission for preparing DCW2, DCW5, and DCW8 was 94 %, 86 % and 65 % lower than that of OPC, respectively. The DCWs can be considered as alternative binders regarding the recycling and immobilization of IFA.

Varying thermal structure controls the dynamics of CO2 emissions from a subtropical reservoir, south China

Thermal stratification and mixing are important to the physicochemical composition of reservoirs and lakes and impact their water quality and biogeochemical cycles. However, it remains unclear how thermal stratification and mixing process control the exchange of CO₂ between surface water and the Earth's atmosphere. To address this issue, we examine the temporal characteristics of some physicochemical parameters, partial pressure of CO₂ (pCO₂), the δ¹³C_DIC, and CO₂ emission from a typical karst groundwater-fed reservoir (Dalongdong reservoir). During the 23 month study (2016-2018) thermal stratification limited CO₂ emission, in part from photosynthetic uptake of CO₂, from early April to late October, while mixing processes stimulated CO₂ emission of CO₂ generated from organic matter remineralization in bottom water from October to April. The Dalongdong reservoir is an atmospheric source of CO₂ for most of the study period; however, during periods of stratification, approximately 0.37 ± 0.44 Gg CO₂ (1 Gg = 10⁹g) dissolved into the water from the atmosphere, while approximately 6.24 ± 3.73 Gg CO₂ was lost to the atmosphere during periods lacking stratification. Limited emissions during stratified period may thus represent a negative feedback to CO₂ contributions to global warming, which has increased lengths of stratified periods. These study results are important to optimize sampling monitoring strategies to reduce errors of regional CO₂ emission estimation.

The role of globalization in CO2 emissions: A semi-parametric panel data analysis for G7

In order to provide flexible and comprehensive results about the relationship between globalization and CO₂ emissions for the G7 countries, we introduce the KOF globalization index into traditional Stochastic Impacts by Regression on Population, Affluence and Technology model, and conduct the empirical analysis by applying a semi-parametric panel fixed effects model. The data covering the period of 1970-2015 consists of CO₂ emissions, KOF globalization index, renewable energy consumption and GDP. Our results indicate that the relationship between globalization and CO₂ emissions are inverted U-sharped, which strongly support the Environmental Kuznets Curve hypothesis. Furthermore, an increase of economic output is associated with statistically significant growth in CO₂ emissions. On the contrary, an increment of renewable energy consumption lowers CO₂ emissions. Related policy proposals are then offered according to our empirical results.

Decomposition and decoupling analysis of carbon dioxide emissions from economic growth in the context of China and the ASEAN countries

China and the Association of Southeast Asian Nations (ASEAN), as the engine of world economic development, are facing tremendous challenges concerning the balance between economic growth and low-carbon development. Nevertheless, previous studies on the relationship between economic growth and carbon emissions have seldom been contextualized in this region. The paper analyses the decoupling elasticity between carbon dioxide (CO₂), the gross domestic product (GDP) and energy consumption in China and the ASEAN countries over the period 1990-2014. Based on the Log-Mean Divisia Index (LMDI), it explores the effect of four factors on the total changes in CO₂ emissions, namely the carbon density effect, energy intensity effect, economic effect in terms of per capita GDP and population effect. The study shows that the economic effect in terms of per capita GDP is the dominant driving force for the increase in CO₂ emissions. The carbon density and population effects also play a role in this regard. Energy intensity has contributed significantly to the decrease in CO₂ emissions in most of the examined countries. To decouple economic growth from environmental pressure, energy policies in China and the ASEAN countries need to scale up the share of renewable energy, increase the efficiency of energy use and implement green development as long-term targets in the region.

Identification of key industries of industrial sector with energy-related CO2 emissions and analysis of their potential for energy conservation and emission reduction in Xinjiang, China

As the world's largest greenhouse gas emitter, China bears an arduous task of energy conservation (EC) and emission reduction (ER). CO₂ arising from energy consumption during industrial processes makes up the vast majority of greenhouse gas emissions in China. It is the key for the Chinese government to achieve its goal of emission reduction in 2030 by identifying key industries with CO₂ emissions and probing into their potential for EC&ER. We used Xinjiang Province of China as a research area. Next, we proposed a method for identifying key industries with CO₂ emissions in Xinjiang's industrial sector and analyzed their energy consumption and CO₂ emission characteristics. Finally, the average energy efficiency index of national industries was used to explore the potential for EC&ER of key industries. Results indicated that (1) the CO2 emissions in industrial sector were 463.35 million tons in 2016, making up 90.72% of its total CO2 emissions from energy consumption, considerably higher than the global and national averages; (2) In 2016, the 8 key industries with energy-related CO₂ emissions determined in this study are all heavy industries whose energy consumption and CO₂ emissions were 119.65 million tce (tons carbon equivalent) and 445.36 million tons respectively, taken up 62.51% and 87.2% of the total amount in Xinjiang. These 8 key industries play a critical role in realizing EC&ER in Xinjiang; (3) In 2016, the eight key industries had the potential to save 74.65 million tce, accounted for 45.79% of the total EC. Their potential for ER were 272.07 million tons of CO₂, equal to 53.27% of the total CO₂ emissions. On this basis, it is recommended that the local government exploit the potential of key industries for EC&ER by improving their energy efficiency.

Straw-derived biochar mitigates CO2 emission through changes in soil pore structure in a wheat-rice rotation system

To better understand the relationships between soil pore structure features and soil CO₂ emission and soil organic carbon (SOC) sequestration following different straw return modes, undisturbed soil cores (0-5 cm and 5-10 cm) were collected from a rice-wheat rotation system under 4 straw return treatments as (1) no straw return (CK), (2) straw direct return (DR), (3) straw biochar return (BR); (4) straw-pig manure fermentation return (FR) for six years. Pore structure parameters including pore size distribution, porosity, connectivity, anisotropy and fractal dimension (FD) were determined using X-ray computer tomography. Soil CO₂ flux and concentrations of SOC, readily oxidable carbon and nutrients were also measured. The results showed that BR and FR had significantly higher SOC concentration than DR and CK. Porosity and number of >500 μm and 500-100 μm macropores, FD and connectivity were significantly highest under FR and was lowest under BR. FR and DR produced 28.1%-32.4% higher C-CO₂ than CK and BR in wheat growing season, and 9.80%-16.9% higher in rice season. Soil CO₂ emission and C concentrations were significantly related to soil pore structure parameters. The CO₂ emission was most significantly related to number of >500 μm pores and FD, indicating that poorly developed pore structure under BR hindered the production and diffusion of CO₂ from soil. These results enhanced our understanding of the relationship between soil pore structure and CO₂ emission following biochar application, and provided evidence for decision making process in choosing proper straw managements to promote SOC sequestration and reduce CO₂ emission.

Efficient CO2 capture by a novel deep eutectic solvent through facile, one-pot synthesis with low energy consumption and feasible regeneration

With steady growth on CO₂ emission over the years, removal of CO₂ from the environment is a critical issue in preventing global warming and climate change. Due to negligible volatility and remarkable thermal stability, ionic liquids have become potential media for CO₂ capture. However, their drawbacks such as high price, toxicity and inefficient energy consumption have severely limited their applications in CO₂ capture. Here, a promising deep eutectic solvent was synthesized by a one-pot method, simply mixing NH₄Cl with monoethanolamine (MEA) at 30 °C for 30 min to form [MEAHCl][MEA] confirmed by ¹H NMR. [MEAHCl][MEA] with EG exhibits a rapid initial kinetics of CO₂ absorption, around 22.5 wt% within 10 min. It also has good thermal-stability, high tolerance to water contents, economically feasibility of regeneration and robust performance in recycle. This novel capture system which can be prepared on-site is feasible for industrialization and offers an efficient, inexpensive and safe system for CO₂ capture.

Assessing climate change impacts on greenhouse gas emissions, N losses in drainage and crop production in a subsurface drained field

Future climate change-driven alterations in precipitation patterns, increases in temperature, and rises in atmospheric carbon dioxide concentration ([CO₂]_atm) are expected to alter agricultural productivity and environmental quality, while high latitude countries like Canada are likely to face more challenges from global climate change. However, potential climate change impact on GHG emissions from tile-drained fields is poorly documented. Accordingly, climate change impacts on GHG emissions, N losses to drainage and crop production in a subsurface-drained field in Southern Quebec, Canada were assessed using calibrated and validated RZWQM2 model. The RZWQM2 model was run for a historical period (1971-2000) and for a future period (2038 to 2070) using data generated from 11 different GCM-RCMs (global climate models coupled with regional climate models). Under the projected warmer and higher rainfall conditions mean drainage flow was predicted to increase by 17%, and the N losses through subsurface drains increase by 47%. Despite the negative effect of warming temperature on crop yield, soybean yield was predicted to increase by 31% due to increased photosynthesis rates and improved crop water use efficiency (WUE) under elevated [CO₂]_atm, while corn yield was reduced by 7% even with elevated [CO₂]_atm because of a shorter life cycle from seedling to maturity resulted from higher temperature. The N₂O emissions would be enhanced by 21% due to greater denitrification and mineralization, while CO₂ emissions would increase by 16% because of more crop biomass accumulation, higher crop residue decomposition, and greater soil microbial activities. Soil organic carbon storage was predicted to decrease 22% faster in the future, which would result in higher global warming potential in turn. This study demonstrates the potential of exacerbating GHG emissions and water quality problems and reduced corn yield under climate change impact in subsurface drained fields in southern Quebec.

Understanding and estimating the carbon dioxide emissions for urban buses at different road locations: A comparison between new-energy buses and conventional diesel buses

Public transport buses are heavy-duty vehicles that travel through the city from morning till night, which emits a large number of greenhouse gases. Understanding and estimating the characteristics of carbon emissions for transit buses are critical in achieving a low-carbon transportation system. In this study, the changes in carbon dioxide (CO₂) emissions generated from new-energy buses as well as traditional diesel buses at bus stations, intersections, and road segments are compared using statistical analysis approaches; then the factors significantly affecting the emission rates are identified based on correlation analysis and feature selection methods. Finally, a gradient boosted regression tree (GBRT) model is proposed to conduct estimations for CO₂ emission rates of buses. The results indicate that different sensitivities to various influencing factors exist in the carbon dioxide emissions of different types of buses. In addition, the VT-Micro regression method and Random forest technique were utilized to compare with the developed GBRT model. According to the comparison results, the estimation errors of GBRT fluctuate in a smaller range, suggesting that the GBRT model outperforms traditional approaches in emission estimation of carbon dioxide. Also, the deep understanding of the emission characteristics for both new-energy buses and conventional diesel buses helps to plan and dispatch buses with different fuel types according to local traffic conditions.

CO2 emission characteristics and reduction responsibility of industrial subsectors in China

Industrial subsectors have an important role in reducing China's carbon dioxide (CO₂) emissions. The present study analyzes the CO₂ emission characteristics of selected subsectors. Results show that the electric and heat power sector is the major industrial CO₂ emitter, and CO₂ emissions of most sectors present huge inter-provincial and inter-regional differences. Then, the CO₂ emission reduction responsibility of provincial-level industrial subsectors is confirmed by the decoupling model. Results show that the development of a low-carbon economy in the nonmetal sector is ideal, and the economic growth in Shanxi and Guizhou is moving toward a low-carbon and energy-saving mode. Moreover, the subsectors that each province should focus on are identified. Finally, constructive suggestions for policymakers to promote low-carbon economy and sustainable development are provided.

Effects of fertilizer types and water quality on carbon dioxide emissions from soil in wheat-maize rotations

The use of fertilizers as addition inputs in agricultural systems can increase the yield of wheat and maize, while also stimulating the emission of carbon dioxide from soil that the main man-made greenhouse gas. Our objectives focused on the impact of different types of synthetic fertilizers and water quality. The purposes were to determine the feasibility of using wasted water for irrigation and to relate CO₂ fluxes to the yield of maize and wheat, as well as to select the best fertilizer type with low CO₂ emission and high yield. The experiment consisted of a double factors test focusing on four forms of fertilizer (urea, amine and slow release fertilizer) and the quality of water (reclaimed water and underground water). The results showed that the reclaimed water was not significant on the CO₂ discharge rate, the maize-wheat yield or the soil properties in 2014 or 2015; however, the CO₂ emission increased slightly in 2015. Focusing on fertilizer treatments, the reclaimed water & amine fertilizer treatment (CAF) that had higher cumulative CO₂ emissions was 32.75 t·ha^-1 in 2014 and 33.86 t·ha^-1 in 2015. According to the ratio CO₂/Y, the slow released fertilizer that reduces CO₂ emissions and keeps the yield high is the preferred choice.

An improved production-theoretical approach to decomposing carbon dioxide emissions

Production-theoretical decomposition analysis (PDA), built on production theory and data envelopment analysis, has been widely used to quantify the factors that drive CO₂ emission changes to support policy analysis and making. Existing PDA methods are usually linked to Shephard distance function and Malmquist productivity index. However, decomposition results associated with these methods may be biased and incomplete. The challenges with these methods mainly stem from the problems associated with underestimating disaggregated efficiencies and the infeasibility of linear programming. This paper proposes a modified PDA approach based on a non-radial directional distance function and global Malmquist-Luenberger productivity index. This new approach addresses the problems associated with conventional PDA methods. To show the usefulness of the proposed approach, we apply it to study CO₂ emissions in China and use the bootstrap method to test the statistical significance of the estimated results.