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The pressure on reducing greenhouse gas emissions has increased since the focus on climate change mitigation has grown. As the human development index is directly related to per capita energy consumption, sustainable energy production with reduced carbon footprint is the essential pathway for cleaner environment. Over numerous existing biological processes, hydrogen production via photo fermentation and photolysis of water is considered a more sustainable and economical method of hydrogen production. While both biological modes suffer from certain limitations, such as low yields and low production rates, practical implementation is still a long way off due to these limitations. The unique properties of nanomaterials (NMs) can help increase the efficiency of the biomass to biohydrogen process in significant ways. Applications of organic and inorganic nanoparticles in photocatalytic and photo fermentative hydrogen production is discussed in this paper. This review reports a wide range of applications of nanomaterials including the details of photo fermentative microorganisms and their mechanism of action. The maximum photo fermentative bio-H 2 production was reported in the presence of SiC–Fe 3 O 4 (3.02 mol H 2 /mol acetate), Ni (41 mol H 2 /mol sugar), graphite-C 3 N 4 (64.2 mol H 2 /mol sugar) whereas photocatalytic bio-H 2 yield was highest when Pd–Ni/CdS (54 mmol/g.h), Ni-MO/g-C 3 N 4 (1785 mmol/g.h) and CuO/TiO 2 (20.3 mmol/g.h) nanoparticles were employed. To design photocatalytic systems for practical and scalable use, the future research should be focused on deeper theoretical knowledge of mechanisms of light harvesting, ± charge separation and transport, surface biochemical reactions, semiconductor–liquid interactions, and reactor dynamics. [Display omitted] • Recent developments for improving water photolysis and photo-fermentation are reviewed. • Applications of organic and inorganic nanoparticles in hydrogen production are discussed. • The working principle and mechanism of hydrogen production are discussed. • The influence of key operating factors are presented. • Scope for future research was presented. [ABSTRACT FROM AUTHOR]

This paper investigates the viability of environmental taxes as a means to mitigate greenhouse gas emissions within the European Union (EU) using the panel threshold model on two balanced panel data comprising countries from the European Union: the Northern and Western countries and Southern and Eastern countries for the period 2000–2020. The study's empirical results support the Pigouvian theory for developed countries, as they indicate an optimal minimum threshold for environmental taxes, where these taxes effectively contribute to reducing greenhouse gas emissions. However, the results diverge for emerging countries, revealing a maximum threshold for environmental taxes beyond which their impact in curbing emissions diminishes. To achieve the ambitious goal of climate neutrality, policymakers must adopt a comprehensive and diversified approach. This includes a combination of environmental taxes, more stringent regulations, and emission standards for industries. Additionally, the implementation of carbon pricing mechanisms, promotion of investments in sustainable fuels and technologies, and the establishment of low-carbon emission infrastructure are essential components of this strategy. By integrating these various measures, policymakers can better navigate the path toward climate neutrality and effectively combat climate change in the EU and beyond. [ABSTRACT FROM AUTHOR]

The concept of net-zero, climate-neutral buildings is attracting global attention, and it is widely recognised as a key solution for achieving climate neutrality targets in the construction sector. However, an increasing and confusing abundance of differing labels, definitions, and approaches is increasing worldwide. This article aims to chart the current progress of national net-zero building pathways and identify gaps and challenges that present a significant barrier to industry uptake and decarbonisation of the built environment worldwide. The national net-zero pathways include an analysis of building legislation, policy and voluntary frameworks in four selected countries, Norway, the United Kingdom, the United States and Singapore, which are all leading regional actors in the race to zero and achieving a climate-neutral construction sector. Firstly, the study provides an overview of each country-specific context and motivation related to climate change adaptation and mitigation in the construction sector. Secondly, a review of the essential features from market-leading net-zero definitions, methodologies, schemes, and tools describing specific building approaches is conducted in each investigated country. Finally, based on the selected net-zero building case studies, the article presents the most promising design strategies for both embodied and operational environmental impact reductions, considering each specific climatic and country context. The research results indicated that the system boundaries for embodied and operational indicators (energy or GHG emissions) presented in investigated net-zero frameworks vary significantly. Consequently, there is an urgent need for a harmonised and transparent standardisation to provide coherence through performed life cycle assessments of buildings. In terms of the design strategies for achieving net-zero ambition according to the investigated frameworks, the common approach is the integration of the passive and active design strategies for operational energy or GHG emission reduction. However, it is evident that in some net-zero building examples, the consideration of the embodied environmental impacts and potential reduction strategies is missing because of not being included and mandatory in the national net-zero framework. This work is built upon the current body of knowledge on existing net-zero building frameworks and already constructed buildings and provides practical indications for building policy development and environmental impact reduction strategies in future climate-neutral, net-zero building projects. • A review of the net-zero building frameworks in Norway, the United Kingdom, the United States and Singapore is presented. • Examines design strategies for embodied and operational environmental impact reductions based on net-zero building cases. • System boundaries and compensation options vary significantly among analysed net-zero frameworks. • Integrating climate mitigation measures with resilience design strategies is missing in the current net-zero frameworks. [ABSTRACT FROM AUTHOR]

• Climate policy should be diversified to meet the needs of all countries. • The ability of renewable energy to solve the emissions problem is questioned. • The energy efficiency has no statistically significant changes in 2010–2020. • There is a contradiction between Sustainable Development Goals 7 and 13. Improving energy efficiency is considered to be important and cost-effective strategies to reduce greenhouse gas emissions, which is crucial in the face of global climate change. This study hypothesizes that there are significant differences in the impact of energy efficiency on economic and energy systems. Using quantile regression method, the impact of economic and energy characteristics on energy-related greenhouse gas emissions in 120 countries over the period 2010–2020 is investigated. Detailed analyses are conducted by dividing the countries into 12 groups based on gross national income per capita (Atlas method) and the share of resource rents in gross domestic product. A macro-level system of indicators for assessing energy efficiency is proposed, which can be linked to the economic and energy characteristics of the systems: National Energy Efficiency, Energy Intensity Ratio, Primary Energy Production Efficiency, Industrial Sector Energy Efficiency, Share of Low Carbon Energy, Population Energy Efficiency. The findings show that (1) global energy efficiency has remained largely unchanged over the decade; (2) there are differences in energy efficiency between fossil fuel producing and non-fossil fuel producing countries; (3) the factors that have an inverse effect on emissions in fossil fuels dependent countries include industrial energy efficiency and population energy efficiency, which are far from exhausting their potential; (4) despite the recognized importance of energy efficiency, its impact on reducing greenhouse gas emissions globally has been unnoticeable. The study highlights that Sustainable Development Goals 7 and 13 on energy affordability and emission reductions are conflicting and require harmonization of mechanisms to achieve them, such as balancing climate change mitigation investments, identifying the potential for energy efficiency improvements across economy or improving energy saving practices. The overall conclusion suggests that there is an urgent need to review current decarbonization and energy efficiency initiatives, given the lack of significant global progress in reducing greenhouse gas emissions or improving energy efficiency between 2010 and 2020. [ABSTRACT FROM AUTHOR]

Greenhouse gas (GHG) emission mitigation and climate change adaptation in urban communities are urgent. There is enormous potential to improve the GHG inventory at the community level. This research aims to develop a community-scale GHG emission inventory and improve its accuracy and consistency through a bottom-up approach. This study covers direct and indirect emissions categorized into three scopes and selects the Honjo Waseda community in Japan as a case study community. Energy consumption from different sectors (the residential and commercial, transport, and waste management sectors) is evaluated and calculated through Residential Energy Estimation based on the Daily Activities (REEDA) database, National Census, and first-hand field data. The outcome revealed that the residential and commercial sector emissions rank highest in the total GHG emissions of the community, with a value of 39 %. Translated into the scope concept, the emissions under scopes 2 and 3 account for 39 % and 61 %, respectively. Furthermore, a sensitivity analysis of the implementation of green technologies to reduce GHG emissions is also conducted. Mechanical biological treatment (MBT) implementation could yield the largest emission reduction (18 %–22 %), followed by implementing electric vehicles, ultralightweight vehicles, photovoltaic systems, and ground heat utilization. [Display omitted] • GHG emission mitigation and climate change adaptation of urban communities are urgent. • Evaluate GHG emission at community level from scope 1–3 through a bottom-up approach. • Develop models for evaluating emissions from residential and commercial transport, and waste management sectors. • Propose scenarios and evaluate sensitivity analysis on green technologies implementation. [ABSTRACT FROM AUTHOR]

Cocoa production is a leading driver of deforestation in the humid-tropics of West Africa. Reconciling climate change mitigation with livelihoods of farmers requires identification of production strategies to concurrently improve yield and profit while curtailing emissions of greenhouse gases (GHG). Using a 2021 plot-survey conducted in Ghana's Eastern region, we evaluated yields, GHG emissions, and value of production (VOP) (a profit indicator) across a typology representing the diversity of systems at plot-level. The typology was constructed by first stratifying plots according to shade levels and variety (hybrid vs. Amazonia) which resulted in three systems: Hybrid sun , hybrid variety under full-sun (little to no shade); Hybrid shade , hybrid and moderate shade (13–25 shade trees ha−1); and Amazonia, Amazonia under predominantly moderate shade. Next, factor analysis and clustering were used to group plots within each system according to cocoa yield, vegetation, management, and (local) climate conditions. Cluster analysis showed that fertiliser, weeding, pruning, hand pollination, cocoa tree density, and shade tree densities of differing heights were most influential for determination across systems. Hybrid shade had the highest net GHG removal rate at −6.8 ± 1.7 (± 95% CI) Mg CO 2 eq ha−1 yr−1: 48% and 127% higher (emissions more negative) respectively over Amazonia and Hybrid sun. Hybrid shade additionally had the highest average and least variable VOP among production systems at 669 ± 564 USD ha−1 yr−1, compared to Hybrid sun and Amazonia at 404 ± 442 and 213 ± 280 USD ha−1 yr−1 respectively. These results point to hybrid cocoa grown under moderate shade of 13–25 shade trees ha−1 as optimal for reconciling climate change mitigation with development in West African cocoa. • Study concurrently evaluates financial profits and GHG balances (N 2 O & CH 4 emissions, CO 2 removals) in West African cocoa. • Plot-level indicators are evaluated across a typology obtained from sample-stratification and clustering. • Hybrid cocoa under moderate shade (13-25 shade trees ha-1) had GHG removal increment of 127% over same variety without shade. • This system too had higher mean profits, thus best reconciling GHG mitigation and economic development for the region. [ABSTRACT FROM AUTHOR]

Efforts to enhance greenhouse gas (GHG) emission reduction in East Asia play a pivotal role on both global and regional scales in advancing climate mitigation strategies. This study aimed to better constrain anthropogenic CO 2 emission estimates by expanding the network of near-surface in-situ stations for CO 2 observations across South Korea. To achieve an optimal CO 2 network design, we conducted an Observing System Simulation Experiment (OSSE) coupled with the Stochastic Lagrangian Transport model (STILT), utilizing meteorological data from the Korean Integrated Model (KIM). Our inversion setup incorporated two CO 2 emission datasets with a 0.1o resolution: EDGAR v6 for prior emissions and GRACED for truth emissions. A uniform model-mismatch error of 3 ppm was introduced across sites. The effectiveness of the existing five in-situ stations, termed the base network, in South Korea was evaluated to gauge their ability to constrain CO 2 surface flux estimates. However, the findings revealed a reduction in flux uncertainty of only 29.2%, which fell short of the desired uncertainty reduction goal. In this base network, the Lotte World Tower (LWT: 37.5126°E, 127.1025°E) in Seoul and the Anmyeondo (AMY: 36.538576° N, 126.330071° E) site in Taean county stood as major contributors, with estimated reductions of 17.48% and 6.35%, respectively. Consequently, we proposed and developed an extended network, identifying seven candidate sites based on consideration of logistical factors, existing infrastructures, and proximity to the emission source regions. An incremental optimization scheme ranked their contributions, resulting in an additional 25% reduction, bringing the total to 54.13%. However, it is noteworthy that diminishing returns (ranging from 13% to less than 0.1%) were observed with an increase in station count mainly due to the possibility that adding a station earlier in the sequence might render subsequent stations redundant. Despite this, the proposed CO 2 network successfully reduced uncertainty in emissions, narrowing the gap with the objectives of the Global Greenhouse Gas Watch (G3W). • Designing CO 2 near-surface observation network over South Korea. • New stations selected considering logistic factors, existing infrastructures, and proximity to emission sources. • The base network was able to reduce 29.18% of the uncertainty in CO 2 emissions. • Extending network, by adding new seven candidate sites, led to a total uncertainty reduction of 54.13%. [ABSTRACT FROM AUTHOR]

Using the recently proposed concept of "design coalitions," this paper analyzes stakeholder participation in a subnational U.S. climate change mitigation policy redesign process. We demonstrate the utility of design coalitions for analyzing policy design processes, contending that it provides an opportunity to examine the understudied "secondary beliefs" of actors as described by the advocacy coalition framework. Our case study consists of an iterative, inductive content analysis of written input to the Regional Greenhouse Gas Initiative's 2016 policy redesign process. We developed a typology of 12 distinct stakeholder types who coalesced in 19 separate design coalitions, each espousing a stance on one of 11 elements of the policy design. These coalitions were dynamic, with radically different sets of stakeholder types participating simultaneously in many different design coalitions without coordination, usually for their own unique reasons. We observe that, although the updated policy reflected many stakeholder's stances, their influence was limited by their exclusion from the agenda-setting phase of this policy redesign process. In this critical era of climate mitigation policy proliferation, it is important to develop a better understanding of climate policy design coalitions and how they engage in and influence climate mitigation policy design processes. • This research expands knowledge of actor engagement in climate policy design processes. • We develop the concept of design coalitions & explore its relevance to climate policy. • Here, actors aligned in design coalitions based on the "secondary beliefs" of the ACF. • Each type of stakeholder participated in a unique set of design coalitions. [ABSTRACT FROM AUTHOR]

Sub-Saharan Africa is a region with a large population living without electricity. This study investigates the grid balancing role of bioenergy in a sub-Saharan Africa's fully renewable power sector to address the energy poverty challenge in the region, using Ghana as a case country. Two methods are employed: the bioenergy estimation method, for deriving Ghana's technical bioenergy potential, and the LUT model, for the power sector transition modelling. The Ghanaian bioenergy potential of 48.3 TWh is applied on the power sector using the LUT model to develop six alternative scenarios, emphasising on the role of bioenergy, greenhouse gas emissions costs, and climate change mitigation policies. The results of the Best Policy Scenario reveal that with an electrical efficiency of 37.2%, 18 TWh of electricity, which is 16.9% of Ghana's electricity demand by 2050, could be produced from bioenergy for grid balancing. Also, the levelised cost of electricity declines from 48.7 €/MW in 2015 to 36.9–46.6 €/MWh in 2050. Whereas the cost of electricity increases to 76.4 €/MWh in the Current Policy Scenario without greenhouse gas emissions costs. The results show the viability of a relatively cheap and bioenergy balanced sustainable renewable power system for the sub-Saharan African region. • The role of modern bioenergy is examined in renewable energy (RE) dominated power systems. • A comprehensive bioenergy potential assessment for the case of Ghana is presented. • Bioenergy provides flexibility in hybrid solar PV-battery dominated power systems. • Levelised cost of electricity for 100% RE ranges from 37 - 46.6 €/MWh in 2050. • Sustainable modern bioenergy contribution in power systems substantially reduces system costs. [ABSTRACT FROM AUTHOR]

This study investigates the impact of alternative fertilization practices on the yield-scaled global warming potential (YS-GWP) in almond orchards. Almond production is a contributor to greenhouse gas emissions, primarily due to nitrogen-based mineral fertilizers. This research aims to identify strategies that reduce the environmental footprint of almond cultivation while maintaining yield. Field experiments were conducted in an almond orchard using three alternative fertigation practices: Advance Grower Practice (AGP), Pump and Fertilize (P&F), and High Frequency Low Concentration (HFLC). AGP is the current practice used by producers to meet annual N demand for almond tree growth; P&F is a reduction in applied N rate in response to measured N concentrations in the groundwater so that the added N and groundwater N reach the same total N applied; HFLC is a practice of applying smaller N rates per individual event. HFLC uses a greater number of fertigation events to reach similar total annual N load as other treatments. Cumulative N 2 O and CH 4 emissions were used to determine GWP by converting the emissions to carbon dioxide equivalents (CO 2 eq) within a 100-year horizon. Nitrous oxide emissions were multiplied by a radiative forcing potential CO 2 eq of 298 and CH 4 by 25 (UNFCCC, 2007). The results revealed that both P&F and HFLC reduced the YS-GWP compared to AGP. HFLC demonstrated 52–78% decrease in GWP per unit of almond yield compared to AGP, while P&F showed 48–58% decrease over AGP. These reductions were attributed to the reduced nitrous oxide emissions associated with P&F and HFLC. Further, P&F and HFLC tended to have higher N use efficiency than AGP. We demonstrate that adopting alternative fertilization practices can effectively mitigate the environmental footprint of almond orchards while maintaining crop yields. These practices offer viable options for almond growers to reduce greenhouse gas emissions, enhance sustainability, and contribute to climate change mitigation. • Applying nitrogen fertilizer at a lower amount and higher frequency reduces nitrous oxide emissions. • This practice tends to have higher nitrogen use efficiency than standard practice. • It maintains commercial yields at the same level as the standard practice. • It lowers Yield Scaled Global Warming Potential more than the standard practice. [ABSTRACT FROM AUTHOR]

Southeast Asia (SEA) is a key producer and exporter of rice, accounting for around 28% of rice produced globally. To effectively mitigate greenhouse gas (GHG) emissions in SEA rice systems, field methane (CH 4) and nitrous oxide (N 2 O) emissions have been intensively studied. However, an integrated assessment of system-level GHG emissions which includes other carbon (C) balance components, such as soil organic carbon (SOC) or energy use, that can positively or negatively influence the net capacity for climate change mitigation is lacking. We conducted a systematic review of published research in SEA rice systems to synthesize findings across four main components of net system emissions: (1) field GHG emissions, (2) energy inputs, (3) residue utilization beyond the field, and (4) SOC change. The objectives were to highlight effective mitigation opportunities and explore cross-component effects to identify tradeoffs and key knowledge gaps. Field GHG emissions were the largest contributor to net system emissions in agreement with existing scientific consensus, with results showing that practices such as floodwater drainage and residue removal are sound options for CH 4 mitigation. On the other hand, increasing SOC potentially provides a large GHG mitigation opportunity, with long-term continuous rice cropping and practices such as residue incorporation and biochar application promoting SOC increase. A reduction in energy inputs was mainly achieved by optimizing agrochemical use, especially N fertilizers. For residue utilization beyond the field, GHG emission mitigation mainly came from preventing open field burning through residue removal. Removed residue can subsequently be used for producing energy that offsets GHG emissions associated with conventional fuel sources (e.g. fossil fuel-based electricity generation) or substituting material used in other production systems. Integrating all four components of net system emissions into one analysis underscores the following two main takeaways. First, the components of field GHG emissions and SOC change are the biggest opportunities for reducing net system emissions and need to be considered for effective climate change mitigation. Second, the reduction of C inputs through residue removal and increased soil aeration through multiple drainage will lower CH 4 emissions but may also potentially decrease SOC stocks over time. Hence, we argue that future research needs to consider cross-component effects to optimize net system emissions, specifically the "stacking" of best management practices for mitigation related to field GHG emissions or SOC change in long-term experiments. • Net system emissions include field CH 4 /N 2 O emissions, energy inputs, residue utilization, and SOC change. • Integrated review highlights cross-component effects of management including tradeoffs. • Field GHG emissions and SOC change are the largest opportunities for mitigation. • Reduced C inputs and drainage decrease CH 4 emissions, but may negatively affect SOC. • "Stacking" of best management practices is a key knowledge gap that warrants research. [ABSTRACT FROM AUTHOR]

Much recent research on climate change mitigation has focused on carbon intensities, i.e. emissions per unit of economic value, to better understand interrelationships of decarbonization with value. This paper studies large tourism enterprises, which account for a large share of tourism's emissions. Based on annual reports, the paper evaluates greenhouse gas emission and revenue interrelationships for a total of n = 29 large tourism companies including airlines, cruise lines and accommodation businesses. Together, these companies represent about 13% (365 Mt CO 2) of global tourism emissions, generating revenues of US$477 billion (in 2019). The paper tracks their total emissions and emission intensities over the period 2015–2019, revealing that large tourism firms are not on track to net-zero. Results show considerable differences in emission intensities between the three tourism subsectors and between individual firms within the subsectors. These findings are discussed against emission reduction needs to mid-century. There is strong evidence that continued growth at industry's expected rates represents an insurmountable barrier to net-zero, contradicting industry narratives of progressively and successfully engaging with climate change mitigation. [ABSTRACT FROM AUTHOR]

The main objective of this study is to analyze and compare greenhouse gas emission profiles, dynamics thereof, and the climate change mitigation efforts of the major players in the global climate change arena, namely the G7 and BRICS countries that are accounting for more than 60% of the world greenhouse gas emissions as in 2017. Given that the energy sector is the major source of the greenhouse emissions in these countries, the framework of sustainable energy development indicators was applied to the comparative analysis. The analysis revealed the differences among the groups of countries in terms of greenhouse gas emission profiles and development trends of these profiles. The convergence of greenhouse gas emission profiles can be noticed between G7 and BRICS countries during 1990–2017 period. Greenhouse gas emissions per capita has decreased in G7 countries and increased in BRICS countries. Energy intensity, economic growth and carbon factor are the main drivers of greenhouse gas emissions per capita growth in both groups of countries. Carbon factor represents carbon intensity of a country's energy sector and is measured by greenhouse gas emissions per unit of total primary energy supply. The impact of carbon factor was least significant among the main drivers in both groups. Energy intensity was the major driver of decrease in greenhouse gas emissions per capita for both groups, however, the economic growth exceeded the contribution of energy intensity in BRICS countries and greenhouse gas emissions have increased in this group during investigated period. The comparative analysis of greenhouse gas emission profiles development trends and the main drivers of these trends in both groups of countries provides important insights in shaping future climate change mitigation policies and developing greenhouse gas emission reduction targets. Due to the high greenhouse gas profiles, low GHG reduction commitments and insufficient climate change mitigation the Perform, Achieve and Trade (PAT) scheme in India efforts in both groups there is danger of postponing implementation of Paris commitments and achieving the 1.5° target. The policies implemented in high ranked countries, like or Integrated Resources Planning in South Africa or measures under Energy efficiency directive in EU can be applied in low ranked countries by providing the substantial contribution to the country's climate targets. Image 1 • The GHG profiles of G7 and BRICS were converging during 1990–2017. • GHG/capita has decreased in G7 countries and increased in BRICS countries. • Energy intensity, economic growth and carbon factor - the main drivers of GHG/capita. • Energy intensity - the major driver of decrease in GHG/capita for both groups. • However, the economic growth exceeded the contribution of energy intensity in BRICS. [ABSTRACT FROM AUTHOR]

The depth and breadth of the climate crisis is well known, all sectors, industry, government and the individual have the potential to reduce emissions to slow or stop catastrophic climate change. To determine and evaluate the (revealed) preferences of the public in reducing their personal carbon emissions, a conjoint analysis survey, using the PAPRIKA (Potentially All Pairwise RanKings of all possible Alternatives) method, was distributed to the public in a city in the south of England (Southampton). Knowledge of the deep-seated preferences of the public makes a fundamental contribution to future climate actions because it enables publicly acceptable system change to be developed. Results showed the public were unwilling to make large-scale lifestyle changes, even if they would cause large emission reductions. There was a clear preference for making relatively easy, convenient changes to behaviour rather than making more difficult personal lifestyle changes involving diet and transportation. A significant value-action gap is evident, with the public showing high awareness of the seriousness of climate change but showing an unwillingness to make deep cuts to their personal emissions. Demography and personal factors had a relatively low influence over preferences with trends generally staying the same across demographic groups, aside from income brackets. Participants believed that reductions in emissions should come from a 'group effort' from all levels of government, business, environmental groups and individuals. Few participants placed themselves as individual drivers of carbon emission reduction. In order to reduce emissions some form of intervention needs to be made, as the public are not personally willing to make large-scale reductions in carbon emissions, regardless of their environmental awareness or demography. • Public's views on approaches to carbon reduction investigated via conjoint analysis. • Preference for low intensity, 'easy' behaviours not challenging lifestyle changes. • Demographic & personal factors have low influence on carbon reduction preferences. • High awareness of severity of climate change, impacts/priority; also high anxiety. • Desire to consume & "carry on as normal" outweighs self-reported concerns/attitudes. [ABSTRACT FROM AUTHOR]

• Middle-aged forests in the Eastern U.S. have attained about half of their potential carbon stocks. • Most Eastern U.S. forests could continue to accumulate carbon for many decades or several centuries in the absence of harvesting, with relatively low risk of natural disturbances. • In the near term of 20–40 years, reducing harvest will yield the greatest reduction in greenhouse gases compared with business as usual. • How middle-aged forests in the Eastern U.S. are managed can clearly affect their contribution to achieving net-zero GHG emissions by 2050 and beyond. • Our estimated emission reduction from stopping harvest over the 73 million ha studied amounts to 117 Mg CO 2 per year in 2050, equivalent to about 7% of the emissions from using fossil energy in the two ecozones. Increasing harvest would have the opposite effect of increasing emissions by a similar magnitude. • In the longer term of 80 or so years, scenarios converge towards business-as-usual effects on greenhouse gases, but with differences between and within biomes. • The contrast between short- and long-term impacts of different harvest levels is an important consideration for designing land management policies. Middle-aged forests in the Eastern U.S. are broadly defined to consist of forests between the regeneration phase following harvest or disturbance, and an older phase with forests composed of large trees, complex structure, and increasing natural mortality. Study objectives were to develop new carbon accumulation curves based on recent inventory data that represent the actual growth rates of forests as they advance beyond middle age; quantify the projected carbon sink from reducing or increasing harvest of middle-aged forests; and disseminate credible estimates of future carbon stocks in ecosystems and harvested wood products to support policies designed to enhance the role of forests in removing carbon dioxide from the atmosphere and storing it securely. We found that middle-aged Eastern U.S. forests could continue to accumulate carbon for many decades or several centuries in the absence of harvesting, with relatively low risk of natural disturbances. Compared with a recent study that estimated a potential increase in biomass of only 22%, and some analyses that anticipate significant increases in risks from natural disturbances, our results indicate a potential increase of about 100% over current biomass stocks by 2100. Temperate Continental forests have greater potential to increase carbon stock over longer time periods than Subtropical Humid forests. Results from scenario analyses showed that in the near term of 20–40 years, reducing harvest will yield the greatest reduction in net greenhouse gas emissions compared with business as usual. Under an extreme "no-harvest" scenario, C sequestration could increase by about 20 TgC yr−1 in Temperate Continental forests by 2050, and by about 30 TgC yr−1 in Subtropical Humid forests over the same time period. In contrast, a scenario of tripling harvest would increase C emissions by 30 and 60 TgC yr−1 in the Temperate Continental and Subtropical Humid ecozones by 2050, respectively. In the longer term of 80 or so years, all scenarios and "business as usual" converge toward similar impacts on greenhouse gas emissions, nearing neutrality in the Subtropical Humid ecozone but separated by about 30 TgC yr−1 in the Temperate Continental ecozone. Our estimated annual emission reduction from stopping harvest over the 73 million ha of middle-aged forests amounts to 117 Mg CO 2 per year in 2050, equivalent to about 7% of the emissions from using fossil energy in the two ecozones. Increasing harvest would have the opposite effect of increasing emissions by a similar magnitude in 2050. How middle-aged forests in the Eastern U.S. are managed can clearly affect their contribution to achieving net-zero GHG emissions by 2050 and beyond. [ABSTRACT FROM AUTHOR]

The area of ​​Indonesian rice fields in 2016 reached 8.19 million hectares (ha), an increase of 1.16% from the previous year, this number comprising 4.78 million ha of irrigated rice fields and 3.4 million ha of non-irrigated rice fields. In 2017, especially in East Java, the harvest area is 2,278,460 hectares, and rice production is 13,633,701 tons. On the other hand, increasing agricultural activities can also contribute to emissions that can trigger climate change through the greenhouse gases (GHG) produced. GHG is a gas contained in the atmosphere, which absorbs and re-emits infrared radiation. Side effects of greenhouse gas accumulation can cause extreme climate change that affects land productivity. This study aims to analyze rice field productivity and build a greenhouse gas emission model that produce from the rice field productivity system. Emissions to be discussed in this study are CO2, CH4, and N2O. The approach is carried out with a system dynamics because it has the characteristics of a complex, non-linear system dynamics, changes in system behavior over time and feedback that describes new information about the state of the rice productivity system, which will then produce further decisions. The results of this study are causal loop diagram of CH4, CO2 and N2O emissions resulting from the productivity of rice fields modeled using system dynamics. This model contains GHG information generated from the agricultural sector and its impact. This model can be used as a consideration for the government and stakeholders as a reference for making policies for GHG emission mitigation technology as part of smart agriculture. [ABSTRACT FROM AUTHOR]

Abstract Forest-based bioenergy plays an important role in climate mitigation for limiting global mean temperature increase to below 2 °C. The greenhouse gas (GHG) impact of three forest-based bioenergy systems from the USA, Canada and Spain supplying wood pellets for electricity in the UK were evaluated by conducting lifecycle assessments and forest carbon modelling of the three forest systems. Cumulative emissions were analysed by calculating the forest carbon stock change and net GHG emissions balance of the forest-based bioenergy electricity. The analysis considered both the replacement of the existing electricity mix with bioenergy electricity and forest management with and without bioenergy use. The supply chain emissions and forest carbon balances indicated that GHG emission reductions are possible. However, the cumulative net GHG balance at forest landscape scale revealed that the reduction potential is limited, potentially with no GHG reductions in fast growing forests with shorter rotations, while slow growing forest systems with longer rotations result in greater GHG reductions. This means that the maximum climate benefit is delivered at a different point in time for different forest systems. To evaluate the climate change mitigation potential of forest-based bioenergy it is therefore necessary to consider the management, utilisation and relevant counterfactual of the whole forest and its products. In terms of climate change mitigation potential and minimising possible negative impacts that would require multi-level governance. Highlights • Net GHG balance shows GHG reduction potential of forest bioenergy is limited. • Results are dependent on methods, system boundaries and reference system. • Mitigation potential depends on forest management and whole forest product basket. • Multi-level governance framework require to track wider impacts of forest bioenergy. [ABSTRACT FROM AUTHOR]

This paper investigates the potential pathways and associated requirements to meet a goal of net-zero greenhouse gas (GHG) emissions from the US commercial aviation sector by 2050 as outlined in the US 2021 Aviation Climate Action Plan. Aviation traffic (RTK) is projected to grow at an average of 2.0% per annum between 2019 and 2050, suggesting that a progressive and ultimately total decoupling of emissions from traffic growth will be required to meet the US aviation sector goal. Aircraft technology advancements, operational efficiency improvements, sustainable aviation fuels, and market-based measures (MBM) are considered as emissions reductions measures towards the goal. A parametric analysis framework is used to develop low, medium, and high emission reduction scenarios for each of these emissions reduction measures. If aircraft technology, operations, and fuels were frozen at 2019 levels, the aviation sector is projected to emit ≈430 million tonnes of CO 2 (MtCO 2) in 2050. Retirements of older aircraft, replaced by current-generation alternatives, may contribute 17% of the total 2050 emissions reduction goal. Further introduction of advanced aircraft technologies may contribute an additional system-level 11% emissions reductions towards the goal. Operational improvements may contribute ≈2% with a range from 1.5 to 4%. The remaining 70% of emissions in 2050 will be addressed through a combination of sustainable fuels and MBM, where appropriate. The level of contribution from fuels will be dependent on continued production ramp-up to meet aviation demand as well as improvements in lifecycle emissions reduction factor (ERF) for current and future fuel feedstock and production pathways, ranging from 0% for current petroleum-based fuels to 100% for sustainable aviation fuels with zero life-cycle emissions. Meeting a net-zero emissions goal by 2050 with SAF would require an increase in SAF production by 57% annually from 2022 to 2030 and 13% per year thereafter, reaching 100% emissions reductions factor by 2050. MBM may fill the gap between residual lifecycle emissions after accounting for all other in-sector improvement opportunities and the goal. [ABSTRACT FROM AUTHOR]

Food systems contribute 23–42% of global greenhouse gas emissions. Reducing food system emissions is an essential component of climate change mitigation, and a system-wide approach, including production, processing, trade and demand-side transformations, will be needed. Long-term analysis of greenhouse gas (GHG) emissions of food supply is crucial for informing this transformation, and understanding the processes contributing to existing trends can reveal opportunities for future mitigation strategies. To address these needs we used data on food supply, trade and emission intensity to quantify changes in GHG emissions between 1986 and 2017 resulting from food supply in the United Kingdom (UK). Uniquely, the relative contributions of supply-side and demand-side changes to historical trends in food emissions were assessed, and the gap between current UK food consumption and EAT-Lancet recommended diets was used to estimate the additional GHG emission reductions that could be achieved by shifting to the Planetary Health Diet (PHD). It was estimated that in the UK, per-capita GHG emissions from food fell by 32% (from 4.6 tCO 2 eq/capita to 3.1 tCO 2 eq/capita) between 1986 and 2017. Of this 32% reduction, 21% was due to supply-side changes (a fall in emission intensity per unit of production due to increased efficiency of farming practices), 10% was due to demand-side changes (including dietary change and waste reduction), and 2% was due to changing trade patterns. Relative to the PHD, however, the average UK citizen still greatly over-consumes beef, lamb and pork, tubers and starchy vegetables and dairy products, and under-consumes vegetables, nuts, and legumes. It was estimated that by adopting the PHD, UK per capita food emissions could be reduced by a further 42% to 1.8 tCO 2 eq/capita. These results expose the historic contributions of both supply- and demand-side changes to reductions in GHG emissions from food, and highlight the underutilised potential of dietary change in contributing to mitigation of GHG emissions from food. [Display omitted] • UK per-capita food emissions fell by 32% between 1986 and 2017. • Supply and demand-side changes contributed to this reduction. • Adopting the Planetary Health Diet could reduce emissions of UK food supply by 42%. • This reveals the underutilised potential of dietary change as a mitigation strategy. [ABSTRACT FROM AUTHOR]

As the content of the climate policy to meet the 2 °C targets, actions in all economic sectors, including agriculture, are required to mitigate global greenhouse gas (GHG) emissions. Although there has been an ever-increasing focus on agricultural GHG emissions, little is known about the environmental benefits of individual crops, making it challenging to link production to consumption (including trade) and GHG emissions. In this study, we estimated GHG emissions related to rice in 227 countries and three sectors, taking time series data from the Food and Agriculture Organization (FAO) from 1986 to 2017. The results showed that production-based emissions increased by 25.5%, and actual consumption-based presented the same trend while assuming domestic production (no trade) expanded by 45.1%. The reason for the unbalance between the two sectors is that the total transfer volume embodied in the rice trade increased by 151.6% in 32 years. Meanwhile, we found that trade flows increased from low- to high-emission intensity countries, while rice emissions intensity was significantly reduced, contributing to a global GHG emission reduction of an average of 56.3Mt per year. Our results provide a comprehensive, forward-looking assessment of the environmental impacts of global growing rice production and consumption on the main countries and their trading relationships. Thus, besides domestic policies, main importing countries should also consider environmental benefits in developing sustainable international trade to limit the negative environmental impacts of its growing rice consumption. • Differences between production-based and consumption-based GHG emissions are investigated. • GHG transfer embodied in the rice trade regulates the imbalance of production and consumption. • Trade contributed to a reduction of GHG emissions of above 56.3Mt yr−1. • Rice-related emissions deserve more policy attention toward sustainable food systems. [ABSTRACT FROM AUTHOR]

Maritime emission regulations set limits for SOx and NOx emissions for health and environmental reasons, and for CO 2, through the Energy Efficiency Design Index (EEDI), with the general aim of mitigating global warming. EEDI verification is performed at the vessel's design speed and design loads, under calm-water conditions. This, although calm seas are the exception in shipping, and that even with calm-water conditions, ships usually operate at lower speeds than their design speed. A major challenge, if greenhouse gases (GHG) reduction targets are to be met through the EEDI, will be to identify EEDI-compliant solutions that reduce energy consumption and GHG emissions under realistic operational conditions, from lying idle at berth in port to when full power is required in critical situations at sea. In view of all the above, we use the Aframax tanker class to illustrate how such an assessment can be performed, and to display the differences in costs and benefits of options, all of which meet the requirements of the EEDI. [ABSTRACT FROM AUTHOR]

To ensure the use of water today does not damage the prospects for its use by future generations, there is need to understand long-term water demand and supply through energy production, conversion, and use. This study aims to develop an integrated framework to assess the long-term impacts of climate change scenarios on water requirements and greenhouse gas (GHG) emissions. The framework includes the integration of the Water Evaluation And Planning model (WEAP) and the Long-range Energy Alternative Planning Systems model (LEAP). As many countries are planning to move towards a cleaner electricity grid to mitigate climate change, this work attempts to present the impact of various scenarios on water demand, GHG emissions, and cost effectiveness. This is done by conducting a case study of the western Canadian province of Alberta where more than 85% of electricity is generated by fossil fuels. This paper provides a comprehensive overview of nine integrated LEAP-WEAP climate change scenarios for the years 2015–2050 by forecasting water consumption and greenhouse gas emissions from the power sector. The economic aspects of the developed scenarios are discussed in the form of a cost curve that shows the GHG saving potential, water use, and GHG mitigation costs for each scenario. For the Business-As-Usual (BAU) scenario (coal power phase out by 2030), GHG emissions and water demand will fall by 44% and 34%, respectively, in 2030. The integrated results show that the scenarios will mitigate carbon emissions but will result in higher water consumption, which will directly affect water resources in the region. Because of the high investment cost to install the considered renewable power plants in the climate change scenarios, the cost of mitigating carbon emissions in the power sector is high. Early coal-to-gas power plant conversion is the only scenario that is expected to save water (67 million m 3 ) and reduce emissions (40 million tonnes of CO 2 eq.) and be cost effective ($68/tonne of CO 2 eq.). These LEAP-WEAP model results can help create awareness among policy makers to understand the water-energy demand and supply relationship in a quantifiable way. [ABSTRACT FROM AUTHOR]

Biomass plays a dual role as an energy source and a solution for climate change mitigation. There are complexities surrounding decentralized electricity generation, and Ghana could not achieve its 10% renewable energy target in 2020. The paper assesses the greenhouse gas mitigation potential and economic impact of electricity from major food crop residues subjected to anaerobic digestion technology in 16 regions and 88 districts in Ghana from 2017 to 2020. Buswell equation was applied to calculate the biogas and methane yield. The environmental impact assessment was expressed as global warming potential, and the economic feasibility was conducted. The results showed that crop residues' annual theoretical and technical potential was 28.92 Mt and 17.24 Mt. The top four residues with the largest share of technical potential were maize (5.41 Mt), yam (3.58 Mt), plantain (3.05 Mt) and cassava (2.39 Mt). Biogas and electricity potentials were 1,912.74 Mm3 and 3,068.34 GWh, which could offset 15.56% of electricity consumption in Ghana. The Ashanti (478.18 GWh), Eastern (430.20 GWh), Bono East (318.29 GWh) and Northern (314 GWh) regions demonstrated the highest electricity potential. Ghana could generate the highest electricity potential of 46.52 GWh in the districts and a minimum potential of 0.89 GWh annually. Power generation potential from anaerobic digestion had a diesel displacement capacity of 923.35 × 10 6 L with a GHG emissions reduction of 2,507.35 kt CO 2 eq. The largest GHG reduction potential was 38.15 kt CO 2 eq at the district level. The findings show that the project is economically viable, with an average net present value of $ 10,105,904 per region and an electricity cost of $ 0.0321/kWh. The study provides critical insights to policymakers and industry developers for decentralized biomass-based electricity generation in Ghana. • A sustainable crop residue assessment is conducted in Ghana. • The total biogas-based electricity is 3,068.34 GWh. • Ashanti region has high electricity (478.18 GWh) than Greater Accra (9.82 GWh). • The total GHG mitigation is estimated as 2507.35 kt CO 2 eq. • The project is economically viable at a cost of $ 0.0321/kWh. [ABSTRACT FROM AUTHOR]

Climate change mitigation in the agricultural sector is a key policy goal. Marginal abatement cost curves allow comparing the cost-effectiveness of agricultural greenhouse gas mitigation measures. Existing studies often do not account for the heterogeneity of farms and interactions between mitigation measures. The objective of this study is to present a new approach that allows the calculation of a marginal abatement cost curve that considers farm level interaction effects of climate change mitigation measures. We assess the influence of farm structural heterogeneity on the greenhouse gas abatement potential and the corresponding abatement costs when measures are implemented jointly on the farm level. We use the bio-economic farm model FarmDyn to simulate farm-specific abatement potential and mitigation costs for a set of mixed dairy farms in a Swiss case study region (n = 66) and develop an approach to calculate a bottom-up, marginal abatement cost curve based on our sample of farms. Simulation results are used to identify and quantify the effect of heterogeneous farm structures (e.g., size, land use, etc.) on the interactions of climate change mitigation measures using regression analysis. In our study, interaction effects reduce marginal abatement costs by 7% and the overall greenhouse gas abatement potential by 3% compared to a stand-alone consideration of four climate change mitigation measures. Our analysis of how the underlying farm structures affect interaction effects between climate change mitigation measures shows that complex processes on the farm level can have ambiguous effects (i.e., increasing or decreasing greenhouse gas emissions). We conclude that our approach can provide important knowledge about how heterogeneity affects marginal abatement costs when mitigation measures interact with each other. Knowledge about the effectiveness and efficiency of climate change mitigation measures and their interaction effects improves our understanding and development of bottom-up marginal abatement cost curves, which represent an important and widely used tool to inform policymakers and stakeholders on cost-efficient and cost-effective climate change mitigation in agriculture. [Display omitted] • We calculate a marginal abatement cost curve for agricultural greenhouse gas emissions. • Our approach allows to consider interactions between mitigation measures. • The results permit to identify the heterogeneity in marginal abatement costs across farms. • A bio-economic farm level model is used for mixed dairy farms in a Swiss case study region. • Interactions are important for abatement potential and cost-effectiveness. [ABSTRACT FROM AUTHOR]

To translate scientific evidence into policy decisions, a universal, integrate and rapid–calculation model is needed for estimating the air quality associated health co–benefits of climate change mitigation strategies. This study developed such a greenhouse gas policy assessment model (GHG–PAM) based upon the annually published energy balances tables. To examine the applicability of this model, we select Suzhou, one of the national low-carbon pilot cities located in the east of China, as a case study. It was determined that carbon dioxide (CO 2 ) emissions in Suzhou would increase from 148 million tons in 2010 to 297, 284, 180, and 173 million tons in 2020 under Business As Usual (BAU), Industrial Structure Dominated (ISD), Technology Dominated (TD), and Integrate Carbon Reduction (ICR) scenarios, of which only ICR scenario meets its carbon intensity target. Under the ICR scenario, the implementation of greenhouse gas policies reduces the air pollution associated burden of diseases, measured by Disability-Adjusted Life Years (DALY), by 44.1% in 2020 compared to BAU, although even with this scenario the burden of diseases would still be higher than that in 2010. In addition, the model can also identify sectors and industries with greater health co–benefits per unit CO 2 emission reduction, which provides a useful guide for Suzhou's climate policy makers to formulate cost–effective measures. However, it should be carefully used where there is a mismatch between sectors with high potential for CO 2 emission reductions and sectors with high health co–benefits per unit CO 2 emission reduction. [ABSTRACT FROM AUTHOR]

The United Nations Sustainable Development Goal target 7.1, to provide universal access to affordable, reliable and modern energy by 2030, must be achieved in the context of rapid reductions in global greenhouse gas (GHG) emissions. While replacing solid cooking fuels with liquid petroleum gas (LPG) opens questions about the compatibility of energy access and climate mitigation objectives, the environmental impact of 2.6 billion people continuing to rely on solid fuel for cooking and heating is significant. However, models used to map deep decarbonization pathways typically do not feature a granular pathway for universal clean cooking access, which limits the representation of these two interconnected transitions, mitigating climate change and achieving universal energy access. Here, we present a novel methodology for representing residential cooking pathways within the TIMES energy systems optimization model (ESOM) framework. The methodology is demonstrated using India as a proof-of-concept case study, where scenario analysis explores solutions that reach universal clean cooking access in the context of GHG emissions reductions. The model presented here is published and publicly available to access. • Sustainable Development Goal 7.1 targets universal access to clean cooking facilities by 2030. • Energy access and climate mitigation interconnection is underrepresented in energy systems modelling. • The Clean Cooking Model (CCM) represents energy access options in an energy systems optimization framework. • CCM maps cost-optimal, granular pathways to energy access and climate mitigation goals. [ABSTRACT FROM AUTHOR]

Worldwide, cities collaborate in the global effort to manage climate change mitigation. As cities are highly spatially and socially diverse entities, any city encompass a wide range of 'GHG emissions lifestyles' and therefore GHG mitigation strategies should reflect the urban diversity. Advancing sub-urban analysis can improve GHG mitigation by relating efforts and limited resources to the unique characteristics and functioning of different parts of the city. This paper emphasizes the need to relate the unique characteristics of key emissions categories at the residential neighbourhood level to its potential mitigation. It analyses the carbon footprint of households in residential neighbourhoods in the city of Tel Aviv-Jaffa, Israel, focusing on three major direct and indirect emissions categories: electricity, transportation, and food consumption. While the average city scale emissions found to be 4.6 ton of CO 2 e per capita, different neighbourhoods emissions ranged between 3.1 tons and 6.8 tons. Exploring the linkages to various explanatory, socio-spatial drivers found range of emissions related characteristics of different neighbourhoods. Finally, examining the potential contribution of implementing various GHG mitigation measures, revealed that the integration of technological, policy and behavioural measures may result with range of footprint reduction in different parts of the city due to the neighbourhoods' socio-spatial characteristics. • As diverse entities, cities encompass a wide range of GHG 'emissions lifestyles'. • It presents an integrated framework for studying and managing urban neighborhoods GHG emissions. • It explores the linkages between neighbourhoods' footprint, drivers, and potential GHG mitigation. • It could help advancing an efficient urban climate mitigation management. [ABSTRACT FROM AUTHOR]

Cities are a major source of greenhouse gas emissions (GHGs), but they can play a significant role in climate change mitigation by adopting and implementing GHG emission reduction plans, policies and measures. Circular economy measures are recognized to contribute significantly to decarbonization. However, in the literature there is a lack of quantitative analyses on circular measures in cities and their impact on urban GHG emissions. The paper aims to contribute to the literature on the relation between circular cities and climate change mitigation by focusing on circular interventions applicable in three high-impact sectors in cities: energy systems, mobility and built environment, in order to investigate their impacts in terms of emission reductions and contribution to decarbonization. The study covers four cities around the world accounting for more than 10 million of inhabitants and 2,000 km2 of metropolitan area: Bogotá, Colombia; Genoa and Milan, Italy; Glasgow, UK. The methodology uses a Global Trade Analysis Project (GTAP) modelling approach to develop production and consumption-based emission baselines for the four cities and to assess impacts of selected circular measures in the three sectors on the baselines. According to the in-depth analysis of the four considered urban contexts, the majority of the emissions generated by activities carried out within the urban borders are emitted outside the borders in the form of emissions scope 3, thus demonstrating how today's cities are large consumers of goods produced outside their borders, requiring the use of a consumption-based approach for emissions inventory. The results on the modelling of the GHG reduction impact of circular measures show that there is a relevant emission reduction potential in Scope 1 and 2 emissions in cities and highlight the need to prioritize decarbonization of electricity supply in order to ensure relevant emission reductions across the three sectors. The results also demonstrate the potential to reduce supply-chain Scope 3 emissions through urban measures. [Display omitted] • Four different urban contexts around the world are taken in account. • Three sectors are investigated: energy, mobility and built environment. • A consumption-based emission accounting method is used to assess the effective impact of cities. • Impacts of different GHG emission reduction interventions are evaluated for each city. [ABSTRACT FROM AUTHOR]

Farming systems face dual pressures of reducing greenhouse gas (GHG) emissions to mitigate climate change and safeguarding food security to adapt to climate change. Building soil organic carbon (SOC) is proposed as a key strategy for climate change mitigation and adaptation. However, practices that increase SOC may also increase nitrous oxide (N 2 O) emissions, and impact crop yields and on-farm income. A comprehensive assessment of the effects of different management practices on trade-offs between GHG emissions and agricultural systems profitability under climate change is needed. We aimed to: (1) analyze the long-term trends of SOC and N 2 O emissions, and ascertain whether the croplands of the study region are net GHG sources or sinks under climate change; (2) quantify the GHG abatement on a gross margin basis; (3) identify effective management practices that could achieve a win-win strategy; and (4) investigate sources of uncertainty in estimates of GHG emissions and gross margins under climate change. APSIM was used to simulate the effects of three crop residue retention rates (10%, 50% and 100%), and six representative crop rotations (wheat-canola, wheat-field pea-wheat-canola, wheat-field pea-wheat-oats, wheat-wheat-barley, wheat-wheat-canola, and wheat-wheat-oats) under two Shared Socio-economic Pathways scenarios (SSP245 and SSP585) using climate projections from 27 GCMs. GHG emissions and gross margins from 1961 to 2092 were assessed across 204 study sites in southeastern Australia. Our results showed that residue retention can turn the soil from a carbon source (10% retention, 304–450 kg CO 2 -eq ha−1 yr−1) to a carbon sink (100% retention, −269 ∼ −57 kg CO 2 -eq ha−1 yr−1), and the potential of carbon sequestration was partly offset by concomitantly increased N 2 O emissions. The wheat-wheat-canola rotation with full residue retention was shown to be a win-win solution with both large potential of GHG abatement and high gross margin compared with other rotations. Spatial analysis showed that the southeastern part of the study region, with higher rainfall, had higher gross margins, while the drier northwestern part had greater GHG emission reduction potentials. Although climate change led to increased GHG emissions and decreased yields for some crops, these adverse effects were overweighed by the higher SOC and yield advantages from full residue retention. This study emphasizes the significant potential for agronomic management to maximize gross margin and reduce GHG emissions under climate change in southeast Australia. Results from this study could be used by farmers and policymakers to mitigate climate change without compromising agroecosystem profitability. [Display omitted] • APSIM was used to simulate the effects of residue retention and crop rotation on GHG emissions and gross margins. • Retaining all crop residues could turn the soil from a carbon source to a carbon sink, and benefit gross margins. • Enhancement of residue retention on GHG abatement overweighed adverse effects of climate change under SSP245 and SSP585. • The wheat-wheat-canola rotation was the most beneficial in terms of GHG mitigation and profitability compared with others. [ABSTRACT FROM AUTHOR]

The deep decarbonization of the power systems is pivotal to the efforts of global energy transition and climate mitigation. The small modular reactor (SMR) is a decarbonized, reliable and secure generating technology that can bring new possibilities for global power-sector transition. However, such a transition involves a variety of complexities even beyond conventional systems. We comprehensively explore the SMR deployment and the decarbonization pathway in a number of diversified power and jurisdictional systems under various complexities associated with multiple variables, objectives, criteria and constraints that have dynamic and interactive relationships. This effort is based on the development of an SMR-embedded multi-region power system management model (SMPM). Using Canada as an example, here we show that SMRs would play different roles in diversified power systems, particularly for fossil-fuel dependent, highly variable renewable energy-penetrated and off-grid. The introduction of SMRs to Canada would result in up to 71% (/48%) emission reduction from 2005 (/2018) level in the country by 2045. Our results would help show the significance of SMRs for supporting the global energy transition. [Display omitted] • An SMPM model is developed to analyze low-carbon power system transition in Canada. • Multiple complexities and uncertainties in power systems are reflected. • SMR development issue is investigated within a power-system optimization framework. • The regional development of Canada is analyzed by a holistic optimization method. • GHG emissions from Canada's power sector would be 48% lower in 2045 than in 2018. [ABSTRACT FROM AUTHOR]

This study aims to forecast greenhouse gas (GHG) emissions in Hong Kong with an optimal selection of predictors. A review is made on the time-series of the GHG emissions by different sources in 1992–2021. Twenty potential predictors are examined relating to economics, social developments, energy use, waste production and climatic conditions, based on previous studies on GHG emissions and mitigation. Three principal components produce well-fitting linear-log regression models. The model stability over time is verified by expanding window analysis. The model accuracy is assured by a CV(RMSE) of 6.1508% in the testing sets. Based on hierarchical clustering and stepwise regression, the gross floor area of construction projects is the most significant predictor to forecast GHG emissions, followed by the unemployment rate and the total expense in construction works. High levels of the three predictors facilitate GHG mitigation, but cannot meet the carbon neutral target. Carbon reduction technologies should be strengthened in growing construction projects. Electricity related carbon mitigation should be further enhanced. The novelty of this study is to provide insights to updating and prioritizing decarbonization strategies in the next phase of Hong Kong's Climate Action Plan. • The peak and downward trend of GHG emissions are examined in Hong Kong. • Principal components produce well-fitting linear-log regression models with social and economic variables. • Significant predictors to forecast GHG emissions are identified from hierarchical clustering and stepwise regression. • Construction is the top priority in GHG mitigation. • Mitigating electricity-related GHG emissions facilitates meeting carbon neutrality. [ABSTRACT FROM AUTHOR]

• Metal recycling is shown to have significant opportunity for climate change mitigation. • Increased secondary metal production could result in GHG savings up to 40 Gt by 2050. • Demonstration of quantifying cost and emissions in Project Drawdown solutions modeling framework. Materials production is a significant contributor to greenhouse gas (GHG) emissions, and as consumption of commodities and resources continues to increase, so does the environmental footprint of extraction per unit of material. Primary production of metals has been progressing with steadily declining ore grades, resulting in higher energy requirements for extraction and processing of larger ore volumes bearing lower metal concentrations. Secondary production from recycled material stocks requires less energy than primary production and thereby has a lower GHG footprint. An LCA-based assessment of potential future adoption scenarios (Plausible, Ambitious, Maximum) of secondary production in the total global market for major commodity metals was conducted to identify the GHG emissions reductions possible from increased metal recycling and secondary production. The Plausible and Ambitious future scenarios result in 4.5 to 12 Gt of GHG emissions reduction globally from 2014 to 2050, and a Maximum future scenario results in over 42 Gt of GHG emissions reductions for the same period. The results of the analyses of the Plausible and Ambitious scenarios, though not close to maximizing use of total scrap available, clearly indicate that even small increments of improved metal recovery for secondary production have significant potential for GHG emission reductions. Analysis of material feedstock costs was also performed to assess the cost to producers of switching from virgin feedstocks to recycled materials. [ABSTRACT FROM AUTHOR]

• Investments to enhance agricultural growth can generate GHG mitigation co-benefits. • Evidence of GHG mitigation helps to implement global climate change policy. • Better integration of forestry and agricultural actions can generate large emissions reduction impacts. • Opportunity exists for scaling best practices to generate mitigation co-benefits. Global agricultural development programs aim to support smallholder farmers and farming communities by strengthening sustainable and resilient food production systems – which can also promote climate change mitigation as a co-benefit by reducing the emissions and enhancing removals of greenhouse gases (GHG). This study presents estimated GHG emissions reductions of almost 100 agricultural development projects over 51 low- and middle-income countries supported by the International Fund for Agriculture Development (IFAD), USAID-Feed the Future (FTF) Initiative, and Foreign, Commonwealth and Development Office (FCDO, previously DfID). Together, these projects promoted a net GHG emissions reduction of 6.5 MtCO 2 e per year. The forest management and promotion of improved agroforestry systems in the project areas contributed the most to the total mitigation co-benefits of the investment portfolios (∼3.9 MtCO 2 e/y). Improved crop management with minimum tillage practices, residue incorporation, water management in paddy rice, and the use of organic fertilizers also made a large contribution to the GHG emissions reduction (∼1.5 MtCO 2 e/y). Grass and pasture land management across the selected projects account for a net emission reduction of 0.2 MtCO 2 e/y. The implementation of improved agricultural practices in combination proves more effective for improving productivity and generating mitigation co-benefits than used in isolation. However, the aggregate impacts of soil organic carbon (SOC) sequestration should be interpreted carefully, which quickly can be lost quick. The interventions promoted by the global agricultural development programs have shown immense potential in reducing net GHG emissions or emission intensity in agriculture and allied sectors. For moving forward to achieve the net-zero and 1.5 °C goals including food security, the global agriculture development programs need to prioritize working on agriculture policy development and implementation so that agriculture expansion does not continue to drive land-use change. This needs to move from the traditional agriculture development programs to transformational changes. [ABSTRACT FROM AUTHOR]

Transforming and expanding the electricity sector are key for climate change mitigation and alleviation of energy poverty. Future energy systems based on renewable energy sources may reduce greenhouse gas (GHG) emissions but could require more materials during construction. We assess this trade-off by quantifying the requirements of the main bulk materials used in electricity infrastructures for 281 global electricity sector pathways until 2050. We identify main determinants for material requirements and gauge the relevance of socio-economic framework conditions and climate change mitigation regimes. Five selected, highly diverse scenarios are analysed in detail by quantifying their respective annual material stocks and flows, and cumulative GHG emissions to 2050. We find robust evidence that scenarios in line with the 1.5 °C target are associated with significantly higher material requirements than scenarios exceeding a global temperature rise of 2 °C. Material stocks in 2050 differ by up to 30% for copper, 100% for concrete, 150% for iron/steel and 260% for aluminium (3rd quartiles of Monte Carlo simulations), even when the particularly material-intensive "Below 1.5 °C″ scenarios are excluded. Although power plants account for the largest part of the material requirements, grid expansion and reinforcement, necessary to accommodate large shares of volatile power generation and provide universal access to electricity, also cause substantial material demand. In the absence of future GHG mitigation in the processing industries, GHG emissions related to bulk materials (primarily iron/steel and aluminium) could amount to one tenth of the remaining carbon budget for a 50% chance of limiting global warming to 1.5 °C. However, if preference is given to material-efficient technologies, low-carbon processes are applied in the industries and increased material recycling is achieved, GHG emissions related to bulk materials in decarbonisation pathways will not significantly exceed those in largely fossil fuel-based scenarios. • Global electricity sector pathways to 2050 require large amounts of bulk materials. • High-renewable scenarios that meet climate targets are most material-intensive. • Future iron/steel and aluminium requirements imply large greenhouse gas emissions. • Without mitigation, cumulative GHG emissions could be 10% of the 1.5° carbon budget. • Mitigation options include material efficiency, technology development & circularity. [ABSTRACT FROM AUTHOR]

Abstract: While issues of land-use have been considered in many direct analyses of biomass systems, little attention has heretofore been paid to land-use in reference fossil systems. Here we address this limitation by comparing forest biomass systems to reference fossil systems with explicit consideration of land-use in both systems. We estimate and compare the time profiles of greenhouse gas (GHG) emission and cumulative radiative forcing (CRF) of woody biomass systems and reference fossil systems. A life cycle perspective is used that includes all significant elements of both systems, including GHG emissions along the full material and energy chains. We consider the growth dynamics of forests under different management regimes, as well as energy and material substitution effects of harvested biomass. We determine the annual net emissions of CO2, N2O and CH4 for each system over a 240-year period, and then calculate time profiles of CRF as a proxy measurement of climate change impact. The results show greatest potential for climate change mitigation when intensive forest management is applied in the woody biomass system. This methodological framework provides a tool to help determine optimal strategies for managing forests so as to minimize climate change impacts. The inclusion of land-use in the reference system improves the accuracy of quantitative projections of climate benefits of biomass-based systems. [Copyright &y& Elsevier]

Greenhouse gas (GHG) emissions from energy consumption have become a major focus all over the world. Cities, especially, are playing an important role in responding to the challenges of global climate change. However, there is still a lack of case studies on the whole life stage (including energy import, production, and consumption) at the city level. This is the first study to systematically estimate the whole lifecycle GHG emissions of urban energy consumption in Macau using the life cycle assessment (LCA) method. It identifies the main contributors, draws the balance framework diagram of energy GHG emissions, and proposes the effective reduction measures through a scenario analysis. The results show that the total GHG emissions of energy consumption in Macau increased from 2.10 × 103 kt CO 2 eq. in 2000 to 5.34 × 103 kt CO 2 eq. in 2018. In 2018, the energy-related GHG emissions in the import phase, production phase, and consumption phase were 3.37 × 103, 4.08 × 102 and 5.34 × 103 kt CO 2 eq., respectively. Since the return of Macau from Portugal to China (December 20, 1999), its GHG emissions from energy import have come to depend more on Mainland China, increasing from 71% in 2000 to 98% in 2018. For the consumption phase, indirect GHG emissions are more important, accounting for 75.3% of total GHG emissions in Macau. From the final consumption perspective, the gambling industry results in the largest GHG emissions (38.07% in 2018), followed by the transportation industry; while for the final energy consumption types, electricity consumption has become the predominant source. The scenario analysis shows that under an ideal scenario, the GHG emissions can be slowed down and will peak in 2033. [Display omitted] • It firstly estimates the whole lifecycle GHG emissions from Macau urban energy consumption. • The GHG emission dependence on the mainland China increases from 71% to 98% since 2000. • It draws the balance framework diagram of energy GHG emissions. • Gambling industry results in the largest GHG emissions in Macau. • Under ideal scenario, the GHG emissions will peak in 2033. [ABSTRACT FROM AUTHOR]

• We model operational and embodied GHG emissions for Australia's built environment. • The scope includes residential and commercial buildings. • A high ambition scenario delivers a 94% reduction in emissions compared to BAU. • Includes renewables, electrification, efficiency and material replacement. • Novel pathways analysis highlights options for net zero and net negative emissions. Achieving net zero operational and embodied greenhouse gas (GHG) emissions in the built environment is recognised in Australia and globally as a key strategy to address climate change and achieve the United Nations Sustainable Development Goals (SDGs). However, gaps in knowledge remain regarding potential national pathways to achieve this outcome in Australia. This study further extends and applies a national-scale integrated macroeconomic simulation model to explore coherent pathways to net zero emissions in the built environment sector by 2050. The scope of the study includes residential and commercial buildings and both operational and embodied emissions. It applies scenario analysis incorporating different levels of climate ambition, including a shift to renewable energy, electrifying buildings, improving energy efficiency and replacing carbon-intensive materials. We find that a high ambition scenario (Scenario 2) delivers a 94% reduction in GHG emissions by 2050 when compared against business-as-usual, placing a net-zero target within reach. Improvements on Australia's SDGs performance are also attained. Through subsequent pathways analysis we find that achieving net zero or even net negative operational and embodied emissions is feasible with more ambitious action in key areas, including increasing the share of mass-timber buildings and reducing end-of-life losses in sequestered carbon. [ABSTRACT FROM AUTHOR]

Abstract: Pricing greenhouse gas emissions is a burgeoning and possibly lucrative financial means for climate change mitigation. Emissions pricing is being used to fund emissions-abatement technologies and to modify land management to improve carbon sequestration and retention. Here we discuss the principal land-management options under existing and realistic future emissions-price legislation in Australia, and examine them with respect to their anticipated direct and indirect effects on biodiversity. The main ways in which emissions price-driven changes to land management can affect biodiversity are through policies and practices for (1) environmental plantings for carbon sequestration, (2) native regrowth, (3) fire management, (4) forestry, (5) agricultural practices (including cropping and grazing), and (6) feral animal control. While most land-management options available to reduce net greenhouse gas emissions offer clear advantages to increase the viability of native biodiversity, we describe several caveats regarding potentially negative outcomes, and outline components that need to be considered if biodiversity is also to benefit from the new carbon economy. Carbon plantings will only have real biodiversity value if they comprise appropriate native tree species and provide suitable habitats and resources for valued fauna. Such plantings also risk severely altering local hydrology and reducing water availability. Management of regrowth post-agricultural abandonment requires setting appropriate baselines and allowing for thinning in certain circumstances, and improvements to forestry rotation lengths would likely increase carbon-retention capacity and biodiversity value. Prescribed burning to reduce the frequency of high-intensity wildfires in northern Australia is being used as a tool to increase carbon retention. Fire management in southern Australia is not readily amenable for maximising carbon storage potential, but will become increasingly important for biodiversity conservation as the climate warms. Carbon price-based modifications to agriculture that would benefit biodiversity include reductions in tillage frequency and livestock densities, reductions in fertiliser use, and retention and regeneration of native shrubs; however, anticipated shifts to exotic perennial grass species such as buffel grass and kikuyu could have net negative implications for native biodiversity. Finally, it is unlikely that major reductions in greenhouse gas emissions arising from feral animal control are possible, even though reduced densities of feral herbivores will benefit Australian biodiversity greatly. [Copyright &y& Elsevier]

A strong mitigation effort is underway to reduce the levels of anthropogenic greenhouse gas emissions. An allocation of the mitigation effort among multiple agents requires understanding which agent is responsible for what emissions, according to a defined measure of carbon responsibility. The metric adopted by current international climate policy is production-based (or territorial) responsibility. However, other types of responsibility have been discussed in the literature, namely consumption-based (or upstream) responsibility and downstream responsibility. In this paper we study the latter, which is little explored in the literature. We clarify the term through a novel nomenclature, income-based responsibility and present a case-study, with the quantification of income-based responsibility for 112 world regions, and the comparison of the results with production and consumption-based responsibilities. [Copyright &y& Elsevier]

Abstract: The aim of comparative assessment of future road transport technologies is to find the cheapest motor vehicles in terms of private and external Greenhouse Gas (GHG) emission costs under various international climate change mitigation scenarios in 2020 and 2050. The comparative assessment of the main road transport technologies ranging from conventional vehicles to hybrid electric vehicles was performed. The main indicators for comparative future motor vehicles assessment are: private costs and life cycle external costs of GHG emissions. The obtained ranking of road transport technologies allows to identify the most perspective future motor vehicles taking into account international climate change mitigation constraints and to promote these road technologies by policy tools. The cheapest road transport technologies in 2020 and 2050 are: the main results presented in this paper were obtained during EU financed Framework 7 project “PLANETS” dealing with probabilistic long-term assessment of new energy technology scenarios. [Copyright &y& Elsevier]

Rice paddies are a major anthropogenic source of greenhouse gas (GHG) emissions due to the flooding management. Water saving practices often reduce the GHG emissions from rice paddies, yet increase the risk of rice yields loss due to drought stress. Water-saving and drought-resistance rice (WDR) has high drought-tolerant, suggesting that WDR with water-saving management could reduce GHG emissions while maintaining rice yields. However, the effect of WDR on GHG emissions is still unclear. Therefore, we conducted a 2-yr field experiment to assess the effect of WDR on rice yields and GHG emissions under continuous flooding (F), alternate wetting and drying (AWD), and dry cultivation (D) conditions, using a WDR variety and a common variety. Compared to the common variety, the WDR did not affect the rice yields under F and AWD treatments, but increased rice yields by 24% under D treatment. The methane (CH 4) emissions and nitrous oxide (N 2 O) emissions of the two rice varieties were similar. Compared to the F treatment, AWD treatment reduced CH 4 emissions by 7%−64% and area-scaled global warming potential (GWP) by 9%−39% and D treatment reduced CH 4 emissions by 70%−90% and area-scaled GWP by 65%−74%. The WDR with dry cultivation (D -WDR mode) had the lowest area- and yield-scaled GWP. Our findings indicate that it is possible to produce optimal rice yields with low GHG emissions in the D -WDR mode, and suggest that drought-resistance rice variety breeding may benefit climate change mitigation and adaptation efforts. • Interannual greenhouse gases mitigation varied from AWD. • WDR did not affect the rice yields under F and AWD, but increased yields by 24% under D. • D -WDR mode cut methane emissions dramatically with comparable rice yields. • Breeding drought-resistance rice benefits climate change mitigation and adaptation. [ABSTRACT FROM AUTHOR]

• Polypropylene production based on renewable electricity and CO 2 was assessed. • Polypropylene production can lead to net negative greenhouse gas emissions. • This will lead to greenhouse gas emissions reduction when replacing fossil plastics. • In long term applications carbon can be stored from atmosphere to products. The production of plastics is heavily dependent upon fossil feedstocks, thus contributing to global warming. Power-to-X technologies provide new routes to chemicals and plastics production from captured CO 2 and renewable electricity. In this study, CO 2 -based polypropylene production via the methanol-to-olefins route is investigated. The main questions are twofold: 1) whether CO 2 -based polypropylene could be produced with negative net greenhouse gas emissions; and 2) if there is a risk that power-to-polypropylene production would lead to increased land use and water consumption. We performed a cradle-to-gate life cycle assessment with GaBi software to assess the global warming potential, land use and water consumption of CO 2 -based polypropylene. The net global warming potential of power-topolypropylene was found to be negative (-0.35 kgCO 2eq kg -1), meaning that more CO 2 from air is embedded in the polypropylene than is emitted during its production.Compared to fossil polypropylene production, power-to-polypropylene has little effect on water consumption but may lead to increased land use, especially through renewable power consumption. It seems that power-to- polypropylene production does have the potential to transform polypropylene production from being a carbon source to having a net negative global warming potential, which globally could play a significant role in climate change mitigation. A long-term carbon sink effect can be possible, if polypropylene is used in durable long-term applications, such as in infrastructure and construction, and its incineration and release of carbon can be avoided. [ABSTRACT FROM AUTHOR]

Rural development projects to develop sustainable agriculture need to be assessed before engaging smallholder farmers at large scale. Data on agricultural systems to produce food, provide income for smallholders and reduce greenhouse-gas (GHG) emissions are scarce in Sub-Saharan Africa countries. Here, we assessed the potential of agroecological practices (AP) on economic benefits to farmers, GHG balance derived from agricultural activities, and efficiency of economic investments to mitigate GHG. The study was based on a NGO rural development project, which promoted AP: agroforestry, compost, and System of Rice Intensification. The economic and GHG mitigation benefits were projected over a period of 20 years on three scenarios. Two scenarios, differing by two expected levels of AP adoption, were compared to a reference one, in which there was no NGO intervention. Socio-economic, yield and soil data were gathered on 192 farms during five growing seasons (2013–2018). The GHG balance was estimated with TropiC Farm Tool and EX-ACT. The GHG emissions were reduced in both scenarios compared to the reference one: −5.2 to −13.6 tCO 2 eq farm−1 yr−1 for scenario 1 and 2 respectively. At the regional scale, the projected amount of C saved per euro invested was estimated at −0.25 tCO 2 eq euro−1 and -0.41 tCO 2 eq Euro−1 (or € 4 to 2.5 tCO 2 eq−1) under scenario 1 and scenario 2. The annual cash flow of farmers increased over the 20 years. Our study highlighted the potential of AP for increasing productivity and profitability of smallholder agricultural systems for the Malagasy farmers, while simultaneously contributing to climate change mitigation. Image 1 • Ex-Act and TropiC Farm Tool assess greenhouse gas balance of farms and development project. • Both tools predicted similar 20-year trends in reductions of greenhouse gas balances. • Agroecological practices increased productivity and profitability of farmers. • Over 20-year period the project is projected to sequester 3.7tCO 2 eq per euro invested. [ABSTRACT FROM AUTHOR]

• The life cycle GHG emissions of wood bio-concretes are evaluated by different methods. • The increase of wood waste content improves the climate change mitigation potential of bio-concrete. • Wood waste transportation distances can be a critical aspect for circular bio-concrete. • The use of wood waste is better for GHG emissions mitigation than virgin sources. • The climate change impact method has a great influence on the final results. This paper aims to assess greenhouse gases' (GHG) emissions in the life cycle of wood bio-concretes (WBC) production when recycled wood shavings (WS) are used as a circular economy (CE) strategy. Two WBC were evaluated, one with a higher content of WS (WBC HC) and another with a lower content (WBC-LC). Different WS recycling and transportation scenarios were evaluated. The Life Cycle Assessment (LCA) methodology was used, considering a cradle-to-gate scope, comparing two methods for calculation of GHG emissions: IPCC GWP100 and GWP bio. The transport analysis was carried out considering the WBC production in 26 Brazilian cities, according to different locations where waste WS are generated. In order to increase the robustness of the study, a sensitivity analysis was performed for: types of WS allocation, the origin of WS (waste x virgin materials), transportation efficiency, and electricity grid matrix. We verified that the waste WS content increase in WBC resulted in climate change mitigation for all cases and scenarios (when the biogenic carbon is considered). However, this benefit can vary according to WS availability and transport efficiency. Therefore, transportation must deserve special attention for the CE evaluation. When the GWP bio method is used and CO 2 capture during the eucalypt growth is accounted for, the GHG emissions of WBC production can be very low (15 kgCO 2 -eq/m³). We conclude that recycling wood waste to use in WBC can be considered a good CO 2 sink and a pathway for the low-carbon and circular construction industry. [ABSTRACT FROM AUTHOR]