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Tea (Camellia sinensis L.), the most popular beverage worldwide and an important cash crop in China, plays a crucial role in the socio-economic landscape. Reactive nitrogen (Nr) loss from tea cultivation in China has become a major environmental problem due to the high input of N fertilizers. However, the scale of the Nr loss and its environmental impact on tea production in China remains unknown. Hence, we conducted a comprehensive meta-analysis of ammonia volatilization (NH 3), nitrogen oxide (NO x), nitrous oxide (N 2 O) emissions, N leaching (total nitrogen, TN), and N runoff (TN) losses in tea plantations in China. The total Nr loss in Chinese tea plantations was 376 Gg yr−1 (149 kg N ha−1 yr−1) in 2014, with N leaching, NH 3 volatilization, N 2 O emissions, NO x emissions, and N runoff losses accounting for 52.2 %, 33.2 %, 7.5 %, 5.4 %, and 1.7 %, respectively. The total Nr loss-related environmental damage cost of tea cultivation reached 9.53 billion CNY yr−1 in 2014, which was 7.7 % of the total tea production output value. The bulk of the environmental damage cost was attributed to NH 3 volatilization (49.1 %), N 2 O emissions (24.9 %), and N leaching (19.2 %). Large Nr losses occurred during tea production in Sichuan, Hubei, Guizhou, Yunnan, Zhejiang, and Hunan provinces, accounting for 17.7 %, 17.0 %, 13.4 %, 10.7 %, 7.6 %, and 7.0 % of the total Nr losses in China, respectively. Our analysis showed that the adoption of integrated nutrient management reduced N fertilizer inputs to 300 kg N ha−1, lowered Nr loss from 376 Gg to 172 Gg yr−1, and reduced the environmental damage cost of N loss by 45.4 %. These findings, along with detailed data on the N balance of tea cultivation, provides critical information needed to develop effective region-specific N nutrient management practices and policies for sustainable and profitable tea crop production in China, and possibly in other similar geographies. [Display omitted] • We quantified the annual reactive nitrogen (Nr) losses from tea plantations in China. • Nitrogen leaching and ammonia volatilization are the major pathways of Nr losses. • The Nr losses associated environmental cost in tea cultivation accounts to 7.7 % of the output value. • Significant variations in Nr losses and consequent damage costs were observed across different tea-growing regions in China. [ABSTRACT FROM AUTHOR]

China's 'dual carbon' goals seek to achieve peak CO 2 emissions before 2030 and carbon neutrality before 2060. China is one of the world's largest emitters of agricultural greenhouse gases. Although existing studies have evaluated GHG mitigation potential in Chinese agriculture, few built models by incorporating socioeconomic conditions, technology diffusion, and carbon pricing policies. This study developed a bottom-up Agricultural Technology Optimisation Model (ATOM) for GHG mitigation, which selected optimal mitigation measure portfolios by minimising costs based on inventories of agricultural GHG and mitigation measures. It was employed to quantify long-term mitigation potential in Chinese agriculture under a range of socioeconomic and carbon pricing scenarios. GHG emissions in Chinese agriculture totalled 720.3 MtCO 2 e in 2017. Assuming an SSP2 scenario, the maximum technical mitigation potential of the evaluated measures in 2060 will be 554.1 MtCO 2 e, with 78.2% contributed by mitigation measures for crop production. 38.9% of this potential is possibly achievable with negative cost mitigation measures, and carbon pricing can help achieve greater emission reductions. Chinese agriculture theoretically possesses significant mitigation potential, but the implementation of mitigation measures may be hindered by multiple obstacles. The government should adopt counterstrategies to ensure that the agricultural sector remains on track to meet China's carbon neutrality goal. • A bottom-up model (ATOM) for agricultural GHG mitigation was developed. • GHG mitigation pathways in Chinese agriculture were simulated. • Chinese agriculture theoretically possesses considerable GHG mitigation potential. • There is spatial heterogeneity in mitigation potential within Chinese agriculture. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to study the decoupling status and mitigation potential of CO2 emissions from China's transport sector over the period 1991–2015. Firstly, this paper utilizes the Log-Mean Divisia Index (LMDI) technique to identify influencing factors, which govern CO2 emissions from China's transport sector. Over the study period, the CO2 coefficient effect (Δ C c f t ) was the main factor for decreasing CO2 emissions. However, the economic growth effect (Δ C g t ) was the main factor for increasing CO2 emissions. Then, the decoupling indicator is also constructed based on the above influencing factors, which can be utilized to reflect the dependence degree of economic development on CO2 emissions from China's transport sector. During 1991–2015, the CO2 emissions from China's transport sector presented expansive coupling (EC) with economic development. Weak decoupling (WD) only appeared in the sub-period 1991–1995. The CO 2 emissions only presented 3 decoupling grades in all sub-period and the period 1991–2015: Ⅱ, Ⅲ, and Ⅳ. Furthermore, the above influencing factors are also used to establish a theoretical mitigation model, which is used to reflect the mitigation potential of CO2 emissions from China's transport sector. Finally, the occurrence of CO2 mitigation only appeared in 3 sub-periods: 1991–1995, 2005–2010, and 2010–2015. • The LMDI technique is used to identify influencing factors. • The decoupling indicator is constructed based on the influencing factors. • The influencing factors are used to establish a theoretical mitigation model. [ABSTRACT FROM AUTHOR]

From the start of China's G20 presidency, China positions itself as a world leader in fighting climate change and emphasizes the wish to 'break a new path for growth'. China aims to peak carbon dioxide (CO 2) emissions by 2030 and cut its greenhouse gas emissions per unit of gross domestic product by 60–65% from 2005 levels by 2030. The pledge is eagerly awaited as China aims to develop a low carbon economy through switching to alternatives to fossil fuels and being technologically energy-efficient. The power industry is the most important industrial sector while the biggest bottleneck for CO 2 emission control in China. This paper develops a technologies-based bottom-up CO 2 mitigation model to assess emission reduction potential of different technologies in the thermal power industry up to 2030. Using 2010 as the reference year, two macro-economic scenarios and four technological scenarios have been set to describe future policy measures for the period of 2015–2030. CO 2 emission trends, reduction potentials and cost curves are demonstrated under different scenarios. The results show that the electric power industry can reach its CO 2 emission peak by 2030 in the middle policy control scenario under macro-economic slow growth. Emissions would peak at 4.6 billion tonnes CO 2 -eq for the least cost scenario, which is 1.78 billion tones CO 2 -eq less than peak the BAU scenario in 2030. This is equivalent to the total CO 2 emissions from 300 MW to 1000 MW coal-fired power plants with 5000 h in 30 provinces and municipalities of China in 2013. This research shows that the top four negative cost-beneficial technology options, 630℃ or 700℃ USC, small hydroelectricity, and nuclear power pressurized water reactor II and III, are the most preferable to be promoted to meet the CO 2 emissions peak target in 2020 and 2030. [ABSTRACT FROM AUTHOR]

Abstract Emissions of greenhouse gases (GHG) from paddy rice are significant, so reducing these emissions has significant potential for climate change mitigation. We investigated alternate wetting and drying (AWD) as part of an integrated management approach to enhance mitigation, together with combinations of mineral nitrogen (N), reduced tillage, a suitable combination of plant residues and well decomposed manure. To quantify GHG emissions, and the potential for mitigation without yield decline, a process-based model, DayCent was used to simulate methane (CH 4) and nitrous oxide (N 2 O) emissions from paddy rice (Oryza sativa L.) in Bangladesh. The four test sites selected were amended with mineral N fertilizer or an organic amendment (rice straw). A good agreement (p < 0.05) was observed between model simulated and measured daily CH 4 flux at most of these test sites with no significant bias. The seasonal CH 4 emission from a site receiving mineral N fertilizer at a rate of 110 kg N ha−1 was predicted by the model to be 210 and 150 kg ha−1 for the water management scenarios of continuous flood (CF) and AWD, respectively. These values compare well with estimates of CH 4 emissions using Intergovernmental Panel on Climate Change tier 1 methods for the different water regimes. Our model results suggest emission factors for N 2 O of 0.4% and 0.6% of applied fertilizer under CF and AWD water regimes, respectively. Based on modelling studies, AWD was found to be an important strategy not only with respect to reducing GHG emissions, but also in terms of cost effectiveness. We also found that integrated management is a promising option for farmers and policy makers interested in either yield increase, GHG mitigation or both. Yield scaled emissions intensity under AWD was found to be about 24% lower than under CF, followed by integrated management. Highlights • Greenhouse gas (GHG) emissions from rice were simulated with the DayCent model. • DayCent simulates methane and nitrous oxide emissions well in paddy rice. • Alternate wet and drying is the most effective mitigation option to mitigate GHGs. • Integrated management is promising for increasing yield and for GHG mitigation. [ABSTRACT FROM AUTHOR]

Abstract Asia has become a major emitter of carbon emissions. To better achieve emission reduction targets, it is necessary to study the characteristics of carbon dioxide emissions in Asia and their emission reduction potential. Firstly, the gravity movement of Asia's carbon dioxide emissions and its leading forces are explored. Then, the Logarithmic Mean Divisia Index method is applied to find the driving factors governing carbon dioxide emissions. Furthermore, this paper establishes a theoretical model of carbon dioxide emission reduction. At last, the influencing factors are utilized to construct a decoupling index, which is used to describe the dependence of economic development on carbon dioxide emissions. The gravity center for Asia's carbon dioxide emissions was an overall movement towards southwest. However, the gravity center for carbon dioxide emissions per capita was an overall movement towards the southeast. The energy intensity effect was the most factor decreasing Asia's carbon dioxide emissions. Only five countries achieved theoretical reduction of carbon dioxide emissions over 2000–2015. However, three countries were failed to achieve the theoretical reduction of carbon dioxide emissions in this period. The economic development in most east Asia and southeast Asia countries was less dependent on energy-related carbon dioxide emissions over the period 2000–2015. Highlights • The gravity movement of Asia's CO2 emissions and its leading forces were explored. • This paper established a theoretical model of carbon dioxide emission reduction. • This paper constructed a decoupling index. [ABSTRACT FROM AUTHOR]

High fertilizer input and nitric oxide (NO) emissions characterize the intensive vegetable production system. However, the amount, geographic distribution, and effective mitigation strategies of NO emissions over Chinese vegetable fields remain largely uncertain. In this study, we developed a data-driven estimate of NO emissions and their spatial pattern in Chinese vegetable fields based on the Random Forest (RF) model. Additionally, we conducted a field experiment in a subtropical vegetable field to investigate the effect of climate-smart practices on NO emissions. The RF model results showed that soil NO emissions from Chinese vegetable fields were sensitive to nitrogen application amount, soil clay content, and pH. The total NO emission from Chinese vegetable fields in 2018 was estimated to be 75.9 Gg NO–N. The urgency to reduce NO emissions in vegetable fields was higher in northern than in southern China. Our meta-analysis and field experiment results suggested that biochar amendment and replacing chemical fertilizers with bio-organic fertilizers were win-win climate-smart management practices for mitigating NO emissions while improving vegetable production. Overall, our study provided new insights into NO emissions in vegetable soil ecosystems and can facilitate the development of regional NO emission inventories and effective mitigation strategies. These findings highlight the importance of adopting sustainable and climate-smart agricultural practices to reduce NO emissions and mitigate their adverse environmental impacts. [Display omitted] • Chinese vegetable fields are a hotspot of NO emissions. • The spatial distribution of NO emissions from vegetable farms has great variability. • The total NO emissions from Chinese vegetable fields were 75.9 Gg NO–N in 2018. • Biochar and bio-organic fertilizer substitution are promising practices to mitigate NO emissions. [ABSTRACT FROM AUTHOR]

Municipal solid waste (MSW) treatment is one of the main anthropogenic sources of greenhouse gases (GHGs). To mitigate the GHG emissions of the MSW sector, it is crucial to describe their emissions evolutions and mechanisms and propose localized mitigation measures on that basis. The logarithmic mean Divisia index model is used to identify the driving forces of MSW-related GHG emissions and explore the mitigation potential. Jiangsu, a typical province in China with 13 prefecture-level cities, is selected as the case study. The results showed that GHG emissions from Jiangsu's MSW treatment has increased by nearly 2.5 Mt in the last 20 years, as incineration replaces landfills. Economic development was the dominant positive driving force, and MSW generation intensity was the dominant negative driving force. Scenario analysis revealed that the carbon peak of MSW management could appear if MSW source separation and recycling (SSR) were implemented, reducing GHG accumulation emissions by approximately 0.3–0.4 Gt during 2022–2060. Referencing the SSR of the Shanghai pattern will generate the greatest mitigation potential of GHG emissions among the different scenario designs. Finally, policy recommendations for priority cities, consideration of population and economic factors, optimization of MSW treatment structures and improvements to SSR are proposed, which could help local- and national-level decision makers in China and other countries design policy guides to promote carbon neutrality, while simultaneously linking current research areas to waste management practices as well as promoting practices in environment and sustainability. [Display omitted] • Greenhouse gas emission of municipal solid waste sector was estimated in 13 cities. • Spatial-temporal evolution of greenhouse gas emission was depicted. • Driving force effects on greenhouse gas emission were quantified. • Carbon neutrality promoting policies were suggested in the future. [ABSTRACT FROM AUTHOR]

Highlights • This study compares the green roof and cool roof for tropical climate. • This study, aims to look at the mitigation potential of green and cool roofs by comparative analysis. • This study first take into account of cool roof's thermal mass, solar reflectance and insulation level, and the effect of green roofs' irrigation rate and vegetation has been examined. Abstract Urban heat island (UHI) can significantly affect building's thermal-energy performance. Urban materials absorb solar and infrared radiation and the accumulated heat is dissipated in the atmosphere increasing further the air temperature. Roofs are envelope components which with advanced solutions such as cool roofs or green roofs can provide significant energy savings in air-conditioned buildings and improved indoor thermal conditions. By means of dynamic simulations in EnergyPlus software a numerical comparative analysis between these two solutions was done in a tropical climate like Singapore's, taking into account climatological, thermal, optical and hydrological variables. Simulations of a typical summer day in Singapore were assessed to determine (i) UHI reductions for different green/cool roof scenarios; (ii) the diurnal heat fluxes dynamics and (iii) the buildings' thermal energy reduction for the investigated cases. The results show that during peak periods (9 am to 5 pm) cool roofs reduce heat gain by about 0.14 KWh/m2 (8%) and green roofs mitigate considerably less to about 0.008 KWh/m2 (0.4%). And for the whole of a summer design day, cool and green roof reduces heat gain by 15.53 (37%) and 13.14 (31%) KWh/m2 respectively. The numerical simulation results confirm that an appropriate selection of roof materials contribute to the reduction of the negative effects of UHI but experimental data for air-conditioned buildings are yet to be carried out. [ABSTRACT FROM AUTHOR]

An increase in the storage of carbon (C) in soil by changing management practices can help to mitigate climate change and increase soil quality. The objective of this study was to evaluate the best management options for reducing greenhouse gas (GHG) emissions. An ecosystem model DayCent was tested for two rice (Oryza sativa L. ) experimental sites in Bangladesh. The sites are under different management practices and we first tested the models ability to simulate SOC turnover, and then estimated the potential for SOC sequestration by comparing change in SOC for each management scenario with baseline management (current farmers’ practices) including conventional tillage, 5% residue incorporation and nitrogen (N) fertilizer. Predicted yield was also compared at both sites to ensure that yield was not compromised by mitigation measures. A control treatment was tested at both sites. At site 1, two other treatments of mineral N fertilizer, and combination of farmyard manure (FYM) and N were tested in a double rice based crop rotation. At site 2, a treatment receiving cowdung (CD) application, and a combination of CD and N were tested in a wheat ( Triticum aestivum L.)-rice based crop rotation. The DayCent model was able to simulate SOC increase from the double rice test sites under unfertilized conditions, considering additional N and C sources in the simulations. Assuming N fertilizer (180 kg N ha −1 yr −1 ) application for site 1, and CD application (25 t ha −1 yr −1 ) for site 2, respectively, as the baseline, four single, and one integrated, scenarios were implemented in the model to predict SOC and yield at both sites. Two additional scenarios with alternate wet and drying (AWD) as a single treatment, and as part of an integrated approach, were also tested for their mitigation potential at site 1. The highest simulated positive impact on SOC development (60% higher than that of the baseline) was observed at site 1 when FYM was used in place of mineral N fertilizer. As there is a yield penalty associated with the use of only FYM, integrated approaches might show more promise, such as inclusion of 15% residue return, reduced tillage, less mineral N fertilizer, FYM addition, with or without AWD. This approach increases SOC by up to 23% while keeping the yield stable (nearly 3.5 t ha −1 ). The application of CD only as determined for baseline of site 2, gives a yield of about 1.8 t ha −1 yr −1 . In contrast nearly two times more yield was obtained under the scenario associated with integrated management which also increases SOC by 30% relative to the baseline at the second site. Net GHG emissions, including nitrous oxide and methane emissions were estimated using the Intergovernmental Panel on Climate Change (IPCC) tier 1 methods, and country specific emission factors (where available), suggests that the integrated management scenario can reduce the net GHG emissions from 0.58-0.82 t carbon dioxide (CO 2 )-eq. ha −1 yr −1 (equivalent to 0.16-0.24 t Ceq. ha −1 yr −1 ) at site 2, while a net reduction in GHGs of nearly 1.00 t CO 2 -eq. ha −1 yr −1 (equivalent to 0.27 t Ceq. ha −1 yr −1 ) at site 1 was only achieved if AWD was also implemented with the integrated management scenario. Future studies could attempt to model non-CO 2 GHGs with a dynamic model. [ABSTRACT FROM AUTHOR]

Livestock farming generates animal manure as a by-product. In comparison to in some countries, manure is hardly used for energy production in Switzerland. A growing awareness of renewable energy needs, resource depletion, and climate challenges make the huge untapped potential of livestock manure very attractive, particularly regarding biogas technology. Here, we assessed the energy and greenhouse gas (GHG) emissions benefits of using manure for biogas, considering its spatial distribution in Switzerland. First, laboratory measurements were conducted to compare the composition of fresh manure with values from literature. Then, detailed assessments of manure availability for biogas production were performed. Finally, the mitigation potential regarding GHG emissions was estimated for three scenarios. The new lab-scale values confirmed early storage as an important phase that is still not considered in practice. Under current farming practice, Swiss manure could produce 430 million m 3 biogas or 15 PJ gross biogas yearly, mostly from cattle. However, only 6% of this manure is currently being used for anaerobic digestion. The manure is widely spread across the country in relatively small farms. Considering the spatial distribution of manure and Swiss agricultural structures, there is considerable potential for small-scale individual installations, with a peak of approximately 250 GJ gross biogas yearly, as well as for joint-farm installations. If the currently exploitable amount of manure were used for energy, the emission of 159 kt of CO 2 equivalent could be prevented compared to emissions under current management practices. Thus, manure digestion could be promoted for its wide environmental and energetic benefits. [ABSTRACT FROM AUTHOR]

Our study focuses on the carbon emission and mitigation potential in the domain of daily travel in Beijing. Using a sample with the focus on working class, the average individual carbon emissions from daily travel are computed as 1.46 kg/day•person and 2.40 kg/day•person for weekday and weekend. Except for residents who need to conduct more long-distance trips, the main contributor to the emissions of the rest high emitters are not the need of longer daily travel distances or the need to conduct more long distance trips, but the need to use cars more intensively for trips with similar distances compared with low emitters. High emitters are associated with the characteristics of being male, having higher income, owning cars, and being in the age between 30s and 40s. On the other hand, living within fifth ring and having good accessibility to public transport are associated with lower emissions. We innovatively use trip-based information to obtain a more relevant and realistic assessment of mitigation potential through mode shift under the current transport system. The mitigation percentage can be as high as 20%–25% if only travel time is considered, but will be substantially constrained by practical barriers. Therefore mitigation policy for daily transport should not only focus on improving travel time of low emission modes to comparable levels with cars but also tackle practical barriers for car drivers to use low emission modes. [ABSTRACT FROM AUTHOR]

The South Korean government released a greenhouse gas (GHG) emission mitigation target for 2030 under the 2015 Paris Agreement and developed a detailed implementation plan in 2016 to achieve the target. In this study, we analyzed the GHG emission reduction potential of South Korea’s transportation sector under the implementation plan. We first identified six technology policy options already adopted or being considered for adoption by the Korean government in the near future. Next, we quantitatively analyzed the GHG emission mitigation potential of each option, as well as the combination of all the options, via the best-known and most widely used bottom-up energy system model. In addition, we estimated the marginal mitigation costs of the options and their combination. We found that more than 30% of GHG emissions can be reduced compared to the business-as-usual scenario by adopting technology options, and that most reductions can be achieved by the road transportation subsector. We also showed that a comprehensive analysis is required to estimate the total potential of the entire transportation sector, because some duplication effects exist between the options. Lastly, based on the comprehensive analysis results, we provide four implications of the plan for climate change and transportation policy makers. [ABSTRACT FROM AUTHOR]

As a key component in mitigating global warming and achieving sustainable development strategies, wind power has received widespread attention and support from governments around the world. Numerous countries are engineering ambitious programs to map and project the mitigation potential of wind energy expansion to combat future global warming. Here, using the global installed wind capacity data, we identity that a total of 837 GW of wind energy installed capacity (WEIC) in 31 countries generated about 2186 TWh of electricity, that is 1311 Mt of CO 2 mitigation, in 2021. Considering power mix transformation, wind power could account for more than 30% of total global electricity generation by the mid-21st century, when many countries expect to realize carbon neutrality, and could reduce CO 2 emission up to 14871 Mt by 2050 and 32864 Mt by 2100. Meanwhile, the global phenomenon of the future southward shift of wind energy resources makes the wind energy development in low-latitude countries, such as Brazil, Vietnam, and Central African, more confident. Combined with the Shared Socio-economic Pathways (SSPs), we find that the mitigation benefits of wind energy expansion are significant and will directly reduce global warming by up to 0.64 °C by the end of the century (NZE deployment scenario, SSP3-7.0). For China and the United States, the share of renewable energy will reach 78% and 84% by 2050 (APS scenario) and the cumulative climate mitigation by wind power will be 0.12 °C and 0.11 °C during 2020–2100, respectively. The findings strongly support the development and practice of global climate mitigation energy solutions. • This study quantifies wind energy's impact on CO 2 and temperatures reduction. • Global wind energy can currently mitigate 1311 Mt CO 2 , up to 32864 Mt by 2100. • Wind energy expansion could mitigate global warming by up to 0.64 °C in 2100. • China and the U.S. lead global CO 2 reductions in wind power. [ABSTRACT FROM AUTHOR]

Rice production consumes large amounts of fertilizer and irrigation water and contributes to the non-point source pollution (NPSP) by delivering nitrogen (N) and phosphorus (P) through surface and subsurface fluxes. However, due to the lack of spatially detailed datasets we barely understand the temporal variations of nutrient fluxes or what the key drivers are. Here, we developed a data-driven model and a rice-specific dataset of fertilizer and irrigation schemes to quantify N and P loss fluxes from China's rice paddies across 2320 counties during 1979–2018. Both of the surface and subsurface fluxes decreased, ∼16 % for N and ∼28 % for P over the past four decades. Instead of a steady decrease, the N surface and subsurface fluxes slightly increase at first, until decrease since 1999 at rates of − 1.2 and − 4.7 kiloton N yr−2, respectively. Similarly, the P surface and subsurface fluxes decline rates jumped to − 0.4 and − 0.2 kiloton P yr−2, respectively. N loss via subsurface flux was slightly prevailing compared with surface runoff, their trends were mainly driven by fertilizer application and extreme rainfall, respectively. P was primarily exported via surface runoff, with its trends jointly driven by extreme rainfall and fertilizer application, while the trends of subsurface P fluxes were largely driven by the latter. Consequently, N and P require different mitigation strategies, with N focusing on optimized fertilizer application and P on optimized water scheme. The combination of mitigation strategies on 20 % of the national rice sowing area accounted for 48 % of N and 70 % of P mitigation potentials under future warming. These findings suggest that we should implement regional specific policy interventions for critical regions and pathways, to effectively alleviate the national NPSP. • Data-driven models are developed for large-scale simulations. • N/P loss from China's rice paddies did not decrease until in recent years. • Trends of losses are mainly driven by extreme rainfall and fertilizer application. • N/P losses can be largely mitigated by optimized water and fertilizer schemes. [ABSTRACT FROM AUTHOR]

Crop residue retention plays an important role in greenhouse gas (GHG) mitigation for global agriculture. To clarify the current status of residue retention and burning as well as the contribution of these processes to GHG dynamics, we conducted a nationwide survey on residue management in China in 2011 and improved the Carbon Accounting and Net Mitigation of Straw return model with updated parameters. The results indicated that residue retention increased from 144 Mt yr −1 in 2001 to 295 Mt yr −1 in 2011, whereas burned residue reached 200 Mt yr −1 in China. Because of these increases in residue retention, the net mitigation related to residue retention increased from 5.3 Tg Ce in 2001 to 13.3 Tg Ce in 2011. Further extension would sequester 15.8 Tg C, which is equivalent to a reduction in emissions of 3.9 Tg Ce from residue burning and a mitigate potential of 3.1 Tg Ce from replacing 1.5 Mt of nitrogen fertilizer. However, the national net mitigation from residue retention would achieve only 45–64% of the total soil C sequestration. The spatial heterogeneity of cropping systems and residue management was determined to have different effects on GHG dynamics. The net mitigation would have a negative value in eight provinces because of incremental increases in methane emissions from rice paddies. Increases in residue retention in the remaining 23 provinces would result in a maximum mitigation potential of 10 Tg Ce yr −1 and offset the carbon dioxide emissions caused by fossil fuel burning by 0.5% from the national value in 2011. Therefore, residue retention has mitigated a substantial amount of GHGs, and extending this strategy has considerable mitigation potential for China's croplands. Our results indicate that the retention and burning of crop residues have an effect on the GHG dynamics in China and represent potential strategies for mitigating climate change via residue management. [ABSTRACT FROM AUTHOR]

The Logarithmic Mean Divisia Index (LMDI) and scenario analysis have been applied respectively to analyze the impact of CO 2 -emission and its potential reduction in China׳s power industry. According to the results of LMDI, there are six factors that affect the carbon emission in the power industry. Electricity intensity (EI), and economic activity (EA) are the primary driving factors for the increment in emissions, accounting for 42.33% and 57.05% of the total increment during 1985 to 2011. Results also demonstrated that energy efficiency (EE) contributed 13.54% abatement during 1985 to 2011, and will play a key role in emission abatement in the future. Furthermore, the paper estimate the trend of power sector׳s carbon dioxide emission under three scenarios (basic, moderate and optimum) in order to determine the mitigation potential. The potential mitigation rate will equal to 22.03% and 37.57% in 2020 in Case A and Case B respectively in 2020. [ABSTRACT FROM AUTHOR]

Energy-related CO 2 emissions of the Chinese manufacturing industry are critically important for China and for the entire world. This study addresses the historical trajectory and features of CO 2 emissions in the Chinese manufacturing industry, investigates the influencing factors of CO 2 emission changes utilizing the logarithmic mean Divisia index (LMDI) method, and explores the mitigation potential based on scenario analyses. The results show the following: (1) CO 2 emissions experienced spectacular but unsteady growth during the 1993–2011 period, although CO 2 emissions intensity presented a downward trend; (2) the coal-dominant emissions structure was subject to an electricity-dominant emissions structure; (3) the smelting and pressing of ferrous metals (C32), manufacture of raw chemical materials and chemical products (C26) and manufacture of non-metallic mineral products (C31) were the top three sectors, combining to account for approximately 60% of total emissions; (4) the economic scale was the major driving factor and energy intensity was the most important diminishing factor of CO 2 emissions, and the effects of the emission coefficient, energy structure and economic structure were minuscule; and (5) CO 2 emissions mitigation in the future will mainly depend on drops in energy intensity, declines in emission coefficient of electricity and upgrades in economic structure – their additive effects on CO 2 emissions reductions will be 5412 Mt in 2020. However, energy structure adjustment with the proportion of electricity increasing is not beneficial in terms of CO 2 emissions reductions, because of electricity's high emission factor. [ABSTRACT FROM AUTHOR]

In 2020, China announced that it aims to achieve carbon neutrality before 2060. Despite the recognition of agriculture's importance in emission mitigation strategies, assessing the non-CO 2 greenhouse gas (GHG) mitigation potentials from this sector remains technically and conceptually challenging. This study developed a bottom-up inventory-based model (the A griculture-induced non-CO 2 G reen H ouse G ases INV entory model) to provide region-specific long-term projections (to 2060) of non-CO 2 GHG emissions (including methane and nitrous oxide) from the Chinese agricultural sector. Seventeen production-side technologies were identified that could reduce on-farm emissions, and their mitigation potentials by 2060 were evaluated. Results showed that agricultural non-CO 2 GHG emissions rose by 34% from 1980 to 2018, and they are projected to increase further by 33% to reach 1153 MtCO 2 -eq yr−1 by 2060. Implementing selected technological adaptations could lead to peak agricultural emissions before 2030 and then reduce them by 32%–50% by 2060. The most effective mitigation measures include feed supplements, feed quality improvements, slow-release fertilizers, and improved water management for paddy fields and uplands. All six regions of China will see a gradual increase in agricultural emissions. South Central China and Southwest China have the largest shares of total national emissions and the greatest mitigation potentials. However, technology adoption faces a series of socio-economic obstacles such as the high cost of technology promotion, smaller farm sizes, farmers' aversion to risk, and a complex set of objectives for agriculture. [ABSTRACT FROM AUTHOR]

Freshwater aquaculture ponds constitute one of the important anthropogenic sources of atmospheric methane (CH 4). Nevertheless, estimates of global CH 4 emissions from freshwater aquaculture have large uncertainties due to a lack of data from different aquaculture types. Furthermore, despite that ebullition is a major pathway of CH 4 in aquatic systems, the quantification of ebullitive CH 4 fluxes from typical freshwater aquaculture ponds has been poorly represented. Here, field measurements of CH 4 fluxes over two years were taken to quantify ebullitive CH 4 fluxes from inland freshwater fish and crab aquaculture ponds in subtropical China. Ebullitive CH 4 fluxes averaged 15.97 ± 1.57 and 11.22 ± 1.26 mg m−2 d−1 in the fish and crab ponds in the first experimental year, respectively, and were 22.86 ± 2.30 and 21.95 ± 2.19 mg m−2 d−1 in the second year. During aquaculture period, ebullition dominated the emission pathways of CH 4 , accounting for 83% and 98% of the total CH 4 emissions in the fish and crab ponds, respectively. Ebullitive CH 4 fluxes exhibited considerable spatial variations, with the lowest flux rates captured at the aeration area due to aerator-use in both the fish and crab ponds. Dissolved oxygen and dissolved organic carbon were the two primary factors that drove ebullitive CH 4 fluxes in both aquaculture ponds. By incorporating global measurement data, we further assessed the CH 4 mitigation potential of aerator use in freshwater aquaculture and revealed the dominant role of ebullition in this mitigation contribution. Together with the rice-based aquaculture, aerator use could reduce CH 4 emissions from freshwater aquaculture ponds globally by 71% and in China by 63%. • Ebullition dominates the pathways of CH 4 emissions from inland aquaculture. • Ebullitive CH 4 fluxes differ with bioturbation to sediment in aquaculture ponds. • Aerator use could reduce global inland aquaculture CH 4 emissions by 71%. • Specific area aerator use benefits the whole aquaculture pond CH 4 mitigation. [ABSTRACT FROM AUTHOR]

As part of an agreement during the COP15, the Brazilian government is fostering several activities intended to mitigate greenhouse gas (GHG) emissions. One of them is the adoption of anaerobic digester (AD) for treating animal manure. Due to a lack of information, we developed a case study in order to evaluate the effect of such initiative for beef cattle feedlots. We considered the net GHG emissions (CH 4 and N 2 O) from the manure generated from 140 beef heifers confined for 90 days in the scope “housing to field application” by including field measurements, literature values, and the offset generated by the AD system through the replacement of conventional sources of nitrogen (N) fertilizer and electricity, respectively. Results showed that direct GHG emissions accounted for 0.14 ± 0.06 kg of carbon dioxide equivalent (CO 2 eq) per kg of animal live weight gain (lwg), with ~ 80% originating from field application, suggesting that this emission does not differ from the conventional manure management (without AD) typically done in Brazil (0.19 ± 0.07 kg of CO 2 eq per kg lwg − 1 ). However, 2.4 MWh and 658.0 kg of N-manure were estimated to be generated as a consequence of the AD utilization, potentially offsetting 0.13 ± 0.01 kg of CO 2 eq kg lwg − 1 or 95% (± 45%) of total direct emissions from the manure management. Although, by replacing fossil fuel sources, i.e. diesel oil, this offset could be increased to 169% (± 47%). In summary, the AD has the potential to significantly mitigate GHG emissions from manure management in beef cattle feedlots, but the effect is indirect and highly dependent on the source to be replaced. In spite of the promising results, more and continuous field measurements for decreasing uncertainties and improving assumptions are required. Identifying shortcomings would be useful not only for the effectiveness of the Brazilian government, but also for worldwide plans in mitigating GHG emissions from beef production systems. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N 2 O) has become the prime ozone depleting atmospheric emission and the third most important anthropogenic greenhouse gas, with a global warming potential approximately 300 times higher than CO 2 . Nitrification and denitrification are processes responsible for N 2 O emission from the soil after nitrogen input. The application of a nitrification inhibitor can reduce N 2 O emissions from these processes. The objective of this study was to assess the effect of two different nitrification inhibitors (dicyandiamide (DCD) and a commercial formulation containing two pyrazole derivatives (PD), 1H-1,2,4-triazole and 3-methylpyrazole) on N 2 O emissions from cattle urine applications for summer grazing conditions in the UK. Experiments were conducted under controlled conditions in a laboratory incubator and under field conditions on a grassland soil. The N 2 O emissions showed similar temporal dynamics in both experiments. DCD concentration in the soil showed an exponential degradation during the experiment, with a half-life of the order of only 10 d (air temperature c. 15 °C). DCD (10 kg ha −1 ) and PD at the highest application rate (3.76 kg ha −1 ) reduced N 2 O emissions by 13% and 29% in the incubation experiment and by 33% and 6% in the field experiment, respectively, although these reductions were not statistically significant ( P > 0.05). Under UK summer grazing conditions, these nitrification inhibitors appear to be less effective at reducing N 2 O emissions than reported for other conditions elsewhere in the literature, presumably due to the higher soil temperature. [ABSTRACT FROM AUTHOR]

Abstract: Many developing countries are acutely vulnerable to global climate changes. Pakistan ranks amongst the top of those nations where vulnerability index due to climate changes is very high. Though many of these are not major contributors to the Green House Gases (GHGs) emissions, yet they have adequate potential to mitigate GHGs in various sectors. The power sector, for instance, is one of the major contributors to GHGs in Pakistan and has prospects of abating GHGs by undertaking alternative and improving measures. The GHG contribution from grid connected power plants can be estimated through baseline emissions factor. This paper has calculated this baseline emission factor by determining annual fossil fuel consumption in the grid connected power plants, their net efficiencies, energy outputs and carbon emissions from each fuel source. The data in this regard has been collected from Pakistan Energy Year Book published in 2009, 2010 and 2011 and through related government agencies. The tools, procedures and methodologies of Intergovernmental Panel on Climate Change (IPCC) and United Nations Framework Convention on Climate Change (UNFCCC) are followed in this regard. The paper has calculated that the weighted average baseline emissions factor for power sector in Pakistan is 0.566tCO2/MWh (tons of carbon dioxide per megawatt hour) for wind and solar power projects and 0.478tCO2/MWh for hydro power projects excluding Karachi Electric Supply Company (KESC) grid and 0.606tCO2/MWh for wind and solar power projects and 0.505tCO2/MWh for hydro by including KESC grid. This baseline emissions factor is also a determinant of the amount of Certified Emission Reductions (CERs) that can be accrued by implementing clean Alternative and Renewable Energy (ARE) projects. The amount of CERs generated by an ARE project also have the prospects to earn the carbon revenue streams. The paper has also suggested measures for mitigating grid emissions. [Copyright &y& Elsevier]

Abstract: The temperature of cities continues to increase because of the heat island phenomenon and the undeniable climatic change. The observed high ambient temperatures intensify the energy problem of cities, deteriorates comfort conditions, put in danger the vulnerable population and amplify the pollution problems. To counterbalance the phenomenon, important mitigation technologies have been developed and proposed. Among them, technologies aiming to increase the albedo of cities and the use of vegetative – green roofs appear to be very promising, presenting a relatively high heat island mitigation potential. This paper aims to present the state of the art on both the above technologies, when applied in the city scale. Tenths of published studies have been analysed. Most of the available data are based on simulation studies using mesoscale modeling techniques while important data are available from the existing experimental studies. When a global increase of the city’s albedo is considered, the expected mean decrease of the average ambient temperature is close to 0.3K per 0.1 rise of the albedo, while the corresponding average decrease of the peak ambient temperature is close to 0.9K. When only cool roofs are considered, the analysis of the existing data shows that the expected depression rate of the average urban ambient temperature varies between 0.1 and 0.33K per 0.1 increase of the roofs albedo with a mean value close to 0.2K. As it concerns green roofs, existing simulation studies show that when applied on a city scale, they may reduce the average ambient temperature between 0.3 and 3K. Detailed analysis of many studies reporting a comparison of the mitigation potential of both technologies has permitted the definition of the limits, the boundaries and the conditions under which the considered technologies reach their better performance, in a synthetic way. [Copyright &y& Elsevier]

Highlights: [•] Green and cool roofs are studied versus their urban heat mitigation potential. [•] Insulation level and thermal mass of cool roofs are examined. [•] Irrigation rate and vegetation type of green roofs are analyzed. [•] Free floating conditions for various climatic regions are used. [Copyright &y& Elsevier]

Abstract: The purpose of this paper is to present a comprehensive assessment of several alternative scenarios from the perspective of sustainable development and climate change by using a highly consistent integrated assessment model. This analysis is based on our research under the Alternative Pathways toward Sustainable Development and Climate stabilization (ALPS) project, the goal of which is to provide alternative plausible future scenarios through quantification of multiple aspects of society. On the basis of estimated pathways regarding socio-economic conditions and climate change, a range of sustainable development indicators are evaluated under various climate stabilization levels [Copyright &y& Elsevier]

Abstract: This paper describes the development of emission scenarios for non-CO2 greenhouse gases in the European Union as consistent with the energy scenarios used for the EU Low carbon Roadmap 2050. The analysis includes estimates of technical mitigation potentials and costs for mitigation of these gases until 2050 in the 27 EU member states. Results show that it would be technically possible to cut overall emissions of non-CO2 greenhouse gases by about half between base year 2005 and 2050 in both of the energy scenarios defined. The adoption of mitigation efforts already in the baseline will, however, significantly depend on the expected development in the carbon price levels in the EU-ETS and non-ETS sectors. [Copyright &y& Elsevier]

Abstract: This work builds on a bottom-up market greenhouse gas (GHG) mitigation approach to determine the mitigation potential of specific activities by introducing two new concepts: the “adaptation potential” (defined as the difference between the sum of costs and benefits of adaptation, over a specified interval), and; “no behest” opportunities (defined as when the benefits of an activity equal or exceed both the costs to the private investor and the society, excluding the benefits of avoided climate change). “No behest” activities are contrasted with “no regrets” opportunities, whose benefits are equal to, or exceed costs to society, excluding the benefits of avoided climate change. The word “behest” conveys the value of requiring little further incentive or regulation to motivate private investors to take advantage of existing economic opportunities. Therefore, “no behest” opportunities are similar to “no regrets” opportunities, but with a greater relevance to private investments that both mitigate and adapt by including the real market benefits and costs of cleaner development options. This work utilises several mathematical methods to remove information asymmetries between market decision-making and what is both economically and environmentally efficient. These methods can be used for both contextually based bottom-up and top-down scenarios in either an adaptation and mitigation framework. The outputs are a quantified change in profitability and parallel GHG emissions of specific activity baselines that are suitable for carbon (C) liability assessment, investment and government emission targets in the current and projected policy environments. These methods can also be used to determine “no behest” activities which have lower private barriers to implementation than “no regrets” activities. [ABSTRACT FROM AUTHOR]

Abstract: A carbon budget was calculated for Tompkins County, NY, a semi-rural upstate county with a population density of 78pp/km2. The costs and potential for several carbon mitigation options were analyzed in four categories: terrestrial C sequestration, local power generation, transportation, and energy end-use efficiency. This study outlines a methodology for conducting this type of local-scale analysis, including sources and calculations adaptable to different localities. Effective carbon mitigation strategies for this county based on costs/MgC and maximum potential include reforestation of abandoned agricultural lands, biomass production for residential heating and co-firing in coal power plants, changes in personal behavior related to transportation (e.g., public transportation), installation of residential energy efficient products such as programmable thermostats or compact fluorescent light bulbs, and development of local wind power. The total county emissions are about 340GgC/year, with biomass sequestration rates of 121GgC/year. The potential for mitigation, assuming full market penetration, amounts to about 234GgC/year (69%), with 100GgC/year (29%) at no net cost to the consumer. The development of local-scale C mitigation plans based on this sort of model of analysis is feasible and would be useful for guiding investments in climate change prevention. [Copyright &y& Elsevier]

Colombia has a total of 27.2 million heads of cattle, ranking fourth among the Latin American countries. Identifying sustainable strategies to mitigate greenhouse gas emissions (GHGE) will help the Colombian government meet their goal of a 51% reduction in national emissions by 2030. Estimation of yield gaps for identifying the potential to improve cattle farms productivity and efficiency in Colombia help on reducing the GHGE intensities from the cattle sector. This paper aims to calculate the gap between attainable and actual milk and meat yields for specialized dairy, dual-purpose, cow-calf, and fattening production systems in 3 agro-ecological zones (AEZ) in Colombia; to identify the main aspects that restrict the meat and milk yields in these production systems; and analyze how closing yield gaps affect the carbon footprint (CF) of meat and milk production. The most suitable AEZs for cattle activities were identified by considering environmental, climatic, edaphic, and land characteristics. From a dataset of 1505 surveyed farms, a yield gap benchmarking analysis for estimating the potential to increase meat and milk yields in each of the identified AEZ was applied. The most productive farms were included in the "best farms" while the rest of the farms belonged to the "farms operating below potential". A "cradle to farm-gate" Life Cycle Assessment was used to calculate the CF. Three scenarios were proposed for closing the yield gaps by 50, 75, and 100%, between the two groups of farms. Three AEZs likely to support cattle activities in Colombia were identified. Average milk production from the farms operating below potential was 45–50% of potential production, and meat was 34–51%, indicating that a potential to achieve increases in milk and meat productivity exists. CFs of 1 kg milk or meat were lower in the groups of best-performing farms than in the groups of farms operating below potential. Yield gaps for milk and meat production can be closed by improving cattle management practices and better technologies. As a general trend, closing the yield gaps decreases the CFs. Our findings contribute to understand the farms' current productive performance and provides key insights into the possible technological and managerial changes for improving the productivity of cattle systems in Colombia. In addition, the study showed how milk and meat CFs can be lowered with the adoption of proper cattle management practices, and better technologies. [Display omitted] • Cattle are responsible for 21% of Colombian GHG emissions, identifying sustainable strategies for its mitigation is crucial. • Yield gap analysis is useful for exploring opportunities to increase yields by identifying factors constraining production. • This study calculated the yield gaps for Colombian cattle systems, their carbon footprints, and proposed mitigation options. • Substantial cattle yield gaps were found, hence there is a considerable scope to improve milk and meat yields in Colombia. • Closing the yield gaps by increasing cattle productivity is an important mitigation strategy of climate change in Colombia. [ABSTRACT FROM AUTHOR]

The Chinese vegetable production system is characterized by high fertilizer inputs and environmental risks. However, the spatial patterns and mitigation potential of greenhouse gas emissions from the Chinese vegetable production systems are unknown. In this study, greenhouse gas emissions and intensity in the Chinese vegetable production systems were quantified via life cycle assessment. The weighted average greenhouse gas emissions and intensity for Chinese vegetable production were 6,244 kg CO 2 -eq ha−1 and 116 kg CO 2 -eq t−1, respectively. The total greenhouse gas emissions were 139 Mt CO 2 -eq. N fertilizer was the largest contributor, accounting for 78.2 % of greenhouse gas emissions. Large variations in greenhouse gas emissions and intensity were detected among the regions as well as cultivation methods. Greenhouse gas emissions in the North region were 9.7–30.0 % greater than those in the South region due to 18.2–58.2 % higher N fertilizer rate in the North region. Greenhouse gas emissions from greenhouse vegetable production were 55.4–84.1 % greater than those from open-field vegetable production because the former had 13.0–51.3 % higher N fertilizer rate and more material structure input. Greenhouse gas intensity for greenhouse vegetable production was 39.6 % higher than that for open-field vegetable production in the North region. In contrast, greenhouse gas intensity was similar for both greenhouse and open-field vegetable production in the South region. The mitigation potential for greenhouse gas emissions on a per-hectare basis was higher for the North region than that for the South region, which was attributed to a relatively greater N fertilizer reduction potential in the North region. Optimizing the N rate could reduce the total greenhouse gas emissions from the Chinese vegetable production systems by 16.7 %. This work could enable researchers and policymakers to reduce the contribution of vegetable production to global climate change. [Display omitted] • The average GHG emission from Chinese vegetable production was 6,244 kg CO 2 -eq ha−1. • The North region had 9.7–30.0 % higher GHG emission than the South region. • The greenhouse system had 55.4–84.1 % higher GHG emission than the open-field system. • The North region had greater GHG mitigation potential than the South region. • Optimizing the N fertilizer rate could reduce the total GHG emission by 16.7 %. [ABSTRACT FROM AUTHOR]

China is undertaking a huge number of building and infrastructure projects. As a large consumer of energy-intensive building material, the construction activities provoke large direct carbon emissions in upstream industrial sectors (i.e. embodied carbon emissions). This paper aims to explore how construction-related climate policies could contribute to future national carbon emission mitigation efforts by employing a demand-side input-output model and scenario analysis. First, a hypothetical extraction approach is used to estimate the overall carbon emissions induced by the construction sector in the base year. Then scenario analysis is conducted to quantify the sector's technical potential for carbon mitigation in 2030 and 2050. We find that implementing construction-related climate measures in China could mitigate 2.5 Gt construction-induced CO2 in 2030, and 6.4 Gt in 2050 — more than Europe's annual total carbon emissions in 2015. More efficient electricity use could make a substantial contribution in the short-term. However, material-related initiatives, especially those focused on metal recycling, could yield significant carbon mitigation from 2030 onwards. Our findings suggest China to optimize the relationship between urbanization and construction to comply with the country's climate commitments better. Mechanisms to reform supply-side incentives, such as mandatory carbon labelling for construction material throughout the supply chain, could offer immediate benefits. • IO model and scenarios are used to evaluate the sectoral induced carbon emission. • Construction-induced carbon mitigation potential in China is quantified. • Implementing construction-related climate measures could mitigate 6.4 GtCO 2 in 2050. • Material-related initiatives could yield significant potential from 2030 onwards. [ABSTRACT FROM AUTHOR]

• The environmental costs at high (HEL) and low (LEL) elevation were quantified. • HEL was lower nitrogen (N) and carbon (C) footprints by 16.2%~17.3% than LEL. • The 26.5% higher yield was mainly contributor to the lower N and C footprints at HEL. • There is great potential for farmers to mitigate the N and C footprints. • Best farmers' management practices could reduce their N and C footprints by 44%~45%. Mountain vegetable production has become a critical source of low heat-resistance vegetables in summer in subtropical regions, but evaluations based on life-cycle assessment (LCA) that are relevant to the environment and economics have not been reported. We conducted a survey to compare the cabbage yield and resource inputs for small-holder farms at a high (HEL, 900–1500 m) and low (LEL, 200–600 m) elevations in a subtropical region in Southwest China. We used LCA to quantify the nitrogen (N) and carbon (C) footprints, and used the yield and environmental impacts gap method to determine the potential to mitigate the environmental impacts of farming at HELs and LELs. The results show that the respective average reactive N (Nr) and greenhouse gas (GHG) emissions for the HEL and LEL were 137.0 kg N ha−1 and 6785 kg CO 2 -eq ha−1, and 126.7 kg N ha−1 and 6153 kg CO 2 -eq ha−1, respectively. The N and C footprints for the HEL were 17.3% and 16.2% lower, respectively, than those for the LEL due to the higher yield at the HEL. The average cabbage yield was 26.5% greater at the HEL (53.2 t ha−1) than at the LEL (42.0 t ha−1). The average total N application rate at the HEL was 455 kg N ha−1, which was 6.0% greater than that at the LEL. There was great potential for yield increases and the mitigation of N and C footprints by farmers at both the HEL and LEL. Compared to the average of all surveyed farmers for HEL and LEL, those farmers whose yields and N fertilizer production efficiency were both higher than the average of all surveyed farmers (HH groups) reduced their N and C footprints by 44.7–49.4% and 44.4–51.2%, respectively, with 34.4–52.3% higher yield and 9.2–19.8% lower N application rate. This study indicates that high yield, low environmental cost, and high economic benefit can be achieved by advancing agronomic management based on the best farmers' practices for vegetable production in a subtropical high-elevation mountain region. [ABSTRACT FROM AUTHOR]

Greenhouse gas emissions from the transport sector of New Zealand have increased rapidly over the last two and half decades despite various policy initiatives by the government. This raises questions over the acceptability and effectiveness of various policies to reduce greenhouse gas emissions from this sector. This study therefore investigates the mitigation potential of various transport policies while considering their costs, benefits and ethical aspects. A multi-criteria analysis technique is adopted to understand how experts (including policy advisers) perceive the costs, benefits, emissions reduction potentials and ethical priorities of New Zealand's transport policies. A total of 26 policy options are identified, and they are categorized under six mitigation policy pathways. The perspectives of experts are sought and aggregated using the Simple Additive Weighting (SAW) technique to compare and evaluate the mitigation policy pathways and policy options. Results demonstrate that increasing active and public transport investment is the most acceptable option followed by travel demand management, a carbon price, electric vehicle support, and support for fuel-efficient vehicles and biofuels. However, in terms of emissions reduction potential, ceasing the import of petrol and diesel cars into New Zealand by 2030 is found to be the strongest policy option. It is expected that the findings of this study will help illuminate the costs, benefits, mitigation potential and ethical aspects of various transport emissions reduction measures and assist policy advisers in identifying the most attractive policies and projects for investment. • Investment in active and public transport is the most preferred transport policy. • Ceasing the import of fossil cars by 2030 has the strongest mitigation potential. • Car-pooling at peak hours is the most ethical transport policy for New Zealand. • Exempting electric vehicles from parking charges is the least preferred policy. • Government's current policy options are mostly among the least preferred policies. [ABSTRACT FROM AUTHOR]

In order to meet growing food demand for the increasing population in China, chemical fertilizer has played a crucial role in increasing crop productivity in recent decades. However, the production of chemical fertilizer causes greenhouse gas (GHG) and atmospheric pollutant emissions, not to mention the effects of increased crop productivity, which creates a large mass of straw to be either burned or abandoned, leading to waste of resources, as well as GHG and atmospheric pollutant emissions. While many studies recognize the importance of substituting chemical fertilizer with straw as an organic alternative, little is known about the potential and spatiotemporal patterns in mitigating GHG and atmospheric pollutant through substituting chemical fertilizer with crop straw during the fertilizer production stage. We examine the potential impact of substituting straw for chemical fertilizer on the spatiotemporal pattern, and also examine the variation of both GHG and atmospheric pollutant emissions through using straw nutrient contents, emission factors, in combination with crop statistical data. Results show that, theoretically, accumulative nitrogen and phosphorus amounts from straw are estimated to be 55440.2 Gg and 16173.3 Gg, respectively, corresponding to 13.5% of total chemical nitrogen fertilizer and 11.5% of chemical phosphorus fertilizer. The substitution of chemical fertilizer with crop straw can mitigate 7088.8 Gg of GHG emissions, 19.9 Gg of NH 3 emissions, 43.6 Gg of NOx emissions and 2.9 Gg of PM 2.5 emissions annually. At the provincial level, Henan, Shandong, Sichuan, Hebei, Heilongjiang, Guangxi, Jiangsu and Anhui have the largest mitigation potential of GHG, NH 3 , NOx and PM 2.5. High crop cultivation areas and yields in these provinces are the main cause of large emission mitigation. On the whole, the substitution of crop straw for chemical fertilizer is an effective measure to achieve crop waste utilization and to mitigate GHG, NH 3 , NOx and PM 2.5 emissions. Finally, we propose three measures: innovation technologies for comprehensive straw utilization; multiple-channel financial support; and enhancing the awareness of resource recycling and environmental protection of farmers; as methods to promote straw-return, and thus achieve theoretical mitigation potential of GHG, NH 3 , NOx and PM 2.5 emissions. • Substitution of chemical fertilizer with straw reduces GHG and pollutant emissions. • High crop cultivation areas and yields dominate the mitigation potential. • Technologies, financial support and awareness is crucial to promote straw return. • Providing the data support for developing life cycle environmental impact of substituting straw for chemical fertilizer. [ABSTRACT FROM AUTHOR]

• Human activities intensively aggravate Nr inputs and change the input structure. • Decoupling of Nr input with GDP indicates the possibility of reducing Nr pollution. • Nr inputs rise from 295.65 Gg in 2015 to 381.37 Gg in 2050 without control. • Under mitigation scenario Nr input in 2050 decreases to 52–64% of the 2015 levels. • The biophysical potential for a sustainable future for urban Nr use exists. Human activities intensify reactive nitrogen (Nr) inputs to the urban system. Excess Nr loss negatively affects environment and human health. Compared with large-scale studies, greater attention should be paid to the urban system as a burgeoning and important Nr creation source. In this study, we investigated the anthropogenic effects on urban Nr inputs (1995–2015) and assessed the potential to mitigate Nr pollution in Guangzhou, China. Here, we show that compared to the national level, the Nr input structure in urban systems is greatly dependent on external Nr inputs, massive Nr emissions during fossil fuel combustion and increasing Haber-Bosch N fixation associated with industrial synthetic production. The relatively slow increase in Nr inputs with rapid GDP growth shows a decoupling of N with economic development. Under baseline conditions, Nr inputs in 2050 can be assumed to rise to 112–138% of the 2015 value. Under the mitigation scenario involving reducing Nr emissions from fossil fuel combustion, increasing recycling rate of industrial N, controlling per capita demand for food and materials and improving N use efficiency, the Nr pollution possibly decreases to 52–64% of the 2015 levels. The combined mitigation scenario suggests that the biophysical potential for a sustainable future for urban Nr use exists. This study provides decision-makers with a novel view and rational strategies for urban N management. [ABSTRACT FROM AUTHOR]