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This study evaluates the environmental impacts associated with the conversion of garden organic waste into value-added products, namely compost or biochar, employing various processes. Three distinct scenarios are considered: composting garden organic waste followed by screening of oversized materials (CBP), pyrolysis of oversized screenings of compost into biochar AP(I), and in-situ conversion of garden organics into biochar AP(II). A comprehensive Life Cycle Assessment (LCA) was conducted using OpenLCA software and life cycle impact assessment was conducted using Recipe 2016 midpoint methodology. The environmental ramifications of each scenario were assessed, optimising transport distances in AP(II) to achieve a functional unit of one tonne of biochar produced within a cradle-to-gate system boundary. For the first time, this study offers a holistic exploration of the benefits of soil biochar application, extending its scope to climate change mitigation, incorporating the optimisation of transport distance and its influence when scaling up the technology. The results revealed that global warming was increased from 125 kgCO 2 eq during composting of garden waste to 232 kgCO 2 eq where oversized screenings of compost is converted to biochar at an off-site facility. However, direct conversion of the oversized organic waste to biochar, without composting, showed reduced global warming impact of 56 kgCO 2 eq, and is thus the most favourable scenario to limit climate impacts of this fraction of organic garden waste. However, among 18 environmental impact indicators studied, eight indicators were either not influenced or did not significantly increase by transport distance to an off-site pyrolysis facility, while the magnitude of 10 impact indicators increased with transport distance. The insights and methodologies presented in this study hold global relevance, based on an actual case study in regional Australia, offering valuable recommendations for sustainable waste management practices and establishing biochar as a carbon-neutral or carbon-negative solution. The findings contribute to existing waste management knowledge and provide guidance for accessible carbon dioxide removal and soil carbon sequestration technologies. [Display omitted] • A comprehensive LCA for valorisation of garden organics was conducted. • Direct conversion of garden organics to biochar showed least potential environmental impacts. • Biochar provides opportunities for avoided, reduced, and removed carbon from atmosphere. • Maximum transport distance has been identified for individual impact categories. [ABSTRACT FROM AUTHOR]

Carbon neutrality strategies have a significant role in climate mitigation efforts. As global concerns regarding climate change continue to increase, achieving carbon neutrality has emerged as a paramount objective for reducing greenhouse gas emissions and limiting the adverse impacts of anthropogenic activities on the environment. This research investigates a wide range of scholarly works to conduct an in-depth analysis and synthesis of the relevant information about carbon neutrality strategies. The review introduces carbon neutrality principles and terminologies, highlighting their importance in climate mitigation. It then proceeds to explore the wide range of strategies employed across different sectors and industries, investigating their effectiveness, scalability, and potential challenges. A multidimensional analysis contrasts the United States Nationally Determined Contributions pathway 2023, China's Nationally Determined contributions 2023, and the EU Directive 2023/2413, assessing their economic, environmental, political, and social impacts. The study evaluates strategies' effectiveness, scalability, and innovation for transitioning to a sustainable, low-carbon future. It fills a gap by analyzing global approaches across the US, China, and the EU, which account for about 50% of the world's total GHG emissions. It evaluates the novel application of diverse strategies, from renewable energy transitions to innovative policy measures, highlighting their potential to mitigate climate change effectively. By providing a multidimensional analysis of these strategies' impacts, the research not only enhances understanding of effective carbon neutrality tactics but also underscores the importance of international cooperation in realizing a sustainable, low-carbon future. • Identifies and analyzes carbon neutrality strategies, emphasizing the need for diverse US, Chinese, and EU approaches. • Evaluate renewable energy, carbon capture, and policy tools for carbon reduction effectiveness, scalability, and innovation. • Highlights the study's novelty in synthesizing current knowledge on carbon neutrality, addressing a significant research gap. • Concludes with strategic ideas for international collaboration and policy development for low-carbon futures. [ABSTRACT FROM AUTHOR]

Many studies have analysed the environmental impact of vegan, vegetarian, or reduced meat diets. To date, literature has not evaluated how diet shifts affect environmental impacts by utilising portfolios which reflect personal nutrition preferences. Further, changing diets could alter the available land for non-food uses. This paper defines novel diet portfolios to outline alternative diet transitions and choices within the population and finds their effect on greenhouse gas (GHG) emissions, primary energy use, and land use in Germany. The aim of this study is to capture how these diet shifts affect land availability and increase the options for land-based climate change mitigation strategies. To do so, a contextualisation is made to compare the use of freed-up land for afforestation or biomethane production (with and without carbon capture and storage). The investigated diet portfolios lead to a reduction of the investigated impacts (GHG emissions: 7–67%; energy use: 5–46%; land use: 6–64%). Additionally, afforestation of freed-up land from each diet portfolio leads to further emission removals of 4–37%. In comparison, using the land to produce energy crops for biomethane production could lead to 2–23% further CO2-eq emission reductions when replacing fossil methane. If biomethane production is paired with carbon capture and storage, emission abatement is increased to 3–34%. This research indicates various short-term pathways to reduce GHG emissions with portfolio diet shifts. Utilising freed-up land for climate change mitigation strategies could prove essential to meet climate targets, but trade-offs with, e.g. biodiversity and ecosystem services exist and should be considered. • Diet portfolios are used to represent realistic population diets. • Diet portfolios include a mixture of 12 different diets. • GHG emissions decrease by 67% if the population adopts a Vegan diet. • Afforestation removes almost double the emissions compared to biomethane. • BECCS has similar GHG abatement to afforestation. [ABSTRACT FROM AUTHOR]

Bioenergy production from sugarcane can be one of the sustainable means of mitigating climate change. This was the central idea of the Conference, "Carbon Balance in the Sugar-Energy Sector," held in Brazil on September 14, 2021. The various panels showed that sugarcane stakeholders, including scientists, farmers, industrialists, and investors, are committed to making large-scale sugarcane production a key ingredient in the mitigation of climate change. Their strategies include sustainable land use and management practices to increase soil carbon sequestration; the large-scale production of biofuel, bioelectricity and bioproducts; negative emission industrial technologies; industrial waste recycling; and sector-specific policies rewarding farmers with carbon credits for avoided greenhouse gas emissions. Therefore, the sugarcane sector is not only key to promoting the social-economic development of Brazil, but also to promoting energy transition, curbing greenhouse gas emissions and consequently, reducing global warming and climate change. • Conference Report: 2021 Carbon balance in the sugar-energy sector. • Carbon Balance in the Sugar-Energy Sector 2021 Conference held by Luiz de Queiroz College of Agriculture (Esalq), University of São Paulo (USP), Piracicaba-SP, Brazil on September 14, 2021. • Sugarcane-derived bioenergy is a key ingredient in fighting climate change while simultaneously maintaining a balanced ecosystem (including enhanced soil health and increased capacity to sequester carbon) and promoting socio-economic development [ABSTRACT FROM AUTHOR]

Vineyards are usually cultivated in soils characterised by low soil organic carbon (SOC) content and have high risks of soil erosion and degradation. Increasing SOC stocks in these cropping systems has the potential to contribute to climate change mitigation through SOC sequestration and to enhance soil quality. We conducted a meta-analysis and compared the SOC stock response ratio, the SOC stock rate of change, and the SOC sequestration rate in vineyards under different SOC sequestration (SCS) practices relative to conventional management. SCS practices included organic amendments (OA), biochar amendments (BC), returning pruning residues to the soil (PR), no-tillage (NT), cover cropping (CC), and several combinations of these practices. The average SOC sequestration rate of SCS management was 7.53 Mg CO 2 -eq. ha−1 yr−1 to a 30-cm soil depth. The highest SOC sequestration rate (11.06 Mg CO 2 -eq. ha−1 yr−1) was achieved under a combination of OA+NT and the lowest (2.82 Mg CO 2 -eq. ha−1 yr−1) was observed under PR treatments. Field experiments performed in particularly hot and dry bioclimatic zones were associated with lower SOC sequestration rates relative to those performed in more temperate areas. The high SOC sequestration rates obtained for many SCS practices, and the large land area dedicated to viticulture worldwide (7.45 Mha), imply that the adoption of SCS practices in vineyards can contribute to the global efforts to offset atmospheric greenhouse gas concentrations via SOC sequestration to mitigate climate change. • Effects of soil carbon sequestration (SCS) practices were assessed in vineyards using a meta-analysis. • All SCS practices led to soil organic carbon (SOC) accumulation in viticultural soils. • The average SOC sequestration rate was 7.53 Mg CO 2 -eq. ha−1 yr−1. • The impact of SCS management on SOC stocks was climate-dependent. [ABSTRACT FROM AUTHOR]

Growing energy demand due to population growth and economic progress has led to the need for intensive climate change mitigation. Negative emissions technologies (NETs) will play an important role in limiting global warming by reducing greenhouse gas concentration in the atmosphere. Available options for NETs can be integrated into energy and climate change policies. However, this strategy requires an assessment tool to select a suitable set of NETs to be integrated. A mathematical framework considering multiple environmental and economic factors under uncertainty is needed for the assessment tool. This paper has two main contributions: (1) development of a novel multi-criteria decision analysis tool based on data envelopment analysis method under neutrosophic environment, and (2) application of this tool in the evaluation of NETs considering the risks associated with the uncertainties in these technologies. The model incorporates uncertainties that result in risks when higher performance levels are assumed. A novel neutrosophic data envelopment analysis (NDEA) model is developed for evaluating NETs; this approach uses neutrosophic set theory to account for membership, nonmembership and indeterminacy in uncertain parameter values. A case study is presented to illustrated this technique. Then, a representative case study considering four alternative options for bioenergy with carbon capture and storage (BECCS) is used to demonstrate the tool. The performance assessment of candidate NETs based on literature data is made. Results show different characteristics of NETs in terms of their sensitivity to expert's risk attitude and perception towards the different dimensions of neutrosophic decision-making environment. For instance, the preference of underground storage over ocean storage for BECCS is evident when improving the technology is assumed to be challenging. Various NETs are evaluated; technologies such as BECCS, and afforestation and reforestation show consistent ranking in different decision environments. The capability of the model to account for uncertainties can allow useful insights to be drawn by policy-makers, and thus, accelerate the deployment of NETs. [ABSTRACT FROM AUTHOR]

Urbanisation and the associated growing climate change burdens pose risks to urban and global climate resilience. Urban greenhouse gas emissions fluctuate over time in response to energy demand, which is influenced by government programmes, economic activity, and demographics. In this research, we investigate the influence of policy on urban energy demand and its consequences on mitigating climate change impacts. Using a case study of Lisbon, Portugal from 2008 to 2016, we illustrate a combined use of an urban energy metabolism assessment coupled with a logarithmic mean Divisia index to isolate the changes in energy-related carbon emissions associated with policy changes. We then link these energy flows to life cycle emissions factors to build a multi-level assessment between local and non-local global warming potential. We find that in 2016 Lisbon's energy flows generated more than 2 Mt of CO 2 -equivalent emissions over their life cycles, 48% of which were direct emissions within the city. This corresponds to a decrease of around 37% in greenhouse gas emissions from 2008. Additionally, we estimate the potential of Lisbon's urban forests to sequester these emissions to understand the potential for climate change mitigation. Results show that Lisbon's urban forest can meet less than 1% of the emissions throughout the assessment period. We discuss the changes, concluding that urban forests are insufficient in size to meet the sequestration demands of the urban energy metabolism, and therefore the focus must be more attuned to reducing fossil fuel use in the urban trade and transport activities. • Carbon emissions from Lisbon's urban energy metabolism are dominated by diesel use in the trade and transportation sectors. • Carbon emissions from Lisbon's urban energy metabolism have decreased following energy policy interventions. • Less than 1% of Lisbon's energy-related carbon emissions are sequestered by urban forests. • Urban forests are insufficient in size to mitigate the demand for carbon sequestration. • Energy policy must focus on reducing urban demand for diesel and petrol by transport activities. [ABSTRACT FROM AUTHOR]

The urgent need for climate change mitigation and the potential threat of energy crisis have allowed the popularity of biomass for biofuels to increase. However, the approaches to assess the climate change impacts of biomass utilization are still questionable. To allow a more accurate assessment, we developed a new framework by integrating six impact components including (1) fossil fuel-derived greenhouse gas (GHG) emissions, (2) biogenic CO 2 emissions-loss, (3) biogenic CO 2 emissions-combustion, (4) emissions from land-use practice change, (5) regrowth for compensation, and (6) difference in carbon sequestration. To illustrate the performance of the framework, seven case studies, which covered the first-, second-, and third-generation biofuels, were conducted. The majority of the positive impacts were contributed to by the fossil fuel-derived emissions, biogenic CO 2 emissions, and regrowth for compensation. For the first-generation biofuels, the life cycle GHG emissions were much higher than those of energy-equivalent fossil fuels (144 and 218 kg CO 2 /GJ for Soybean-to-Biodiesel and Corn-to-Ethanol). The second- and third-generation biofuels had less accountable positive GHG emissions (−62 to 53 kg CO 2 /GJ) due to the offset of negative impacts from land-use practice change and difference in carbon sequestration. However, the negative effects are not determinist. High uncertainty from model-simulated carbon sequestration and decomposition is perceivable. High life cycle GHG emissions for the second- and third-generation biofuels are possible. Image 1 • A new framework was developed to estimate the GHG emissions from biomass utilization. • Different biomass feedstock and conversion technologies were studied as illustrations. • The GHG emissions from the first-generation biofuels can be higher than fossil fuels. • The second- and third-generation biofuels could have negative climate change impact. • High uncertainty is perceivable from model simulation for regrowth and decomposition. [ABSTRACT FROM AUTHOR]