Given that over 70% of global greenhouse gas emissions (GHG) stem from consumption, it is essential to promote lifestyle changes among end users and reduce emissions embedded in the upstream supply chain. We investigated the long-term (1990-2020) changes in household carbon footprints from such final users in Japan. Through factor decomposition, we found that the contribution of increasingly green technologies to household decarbonization is diminishing with time. In contrast, lifestyle changes - such as the shift to green products and services, as well as a reduction in overall demand - are becoming the main driver. Additionally, unlike most developed countries, the share of GHG emissions from food expenditures in Japan does not show a declining trend, highlighting the need to upgrade the domestic food supply chain and promote smart services for decarbonizing both homemade meals and eat-out preferences. Our long-term database can provide references to encourage sustainable behaviors and help Japanese policymakers evaluate the effectiveness of current efforts.

Circular economy strategies encompass a wide range of approaches and initiatives designed to foster sustainable resource utilization and minimize waste, particularly in the context of complex products such as automobiles. These strategies encompass, among others, material recycling and reuse, energy recovery, efficiency enhancements, and circular-focused product design. To evaluate the potential of different circular economy strategies to reduce greenhouse gas emissions in China’s automobile manufacturing, this research employs the input-output subsystems approach to analyze three distinct scenarios based on the interconnections between various components: the low-carbon transition of the energy structure, closed-loop material recycling, and the transition to shared mobility. The findings reveal that spillover component emissions account for over 98% of the total emissions of the automobile manufacturing sector. The circular economy model, through material recycling, can significantly cut down emissions from these spillover components, thereby aiding the automobile manufacturing industry in meeting its emission reduction targets. Notably, compared to relying solely on the low-carbon transition of the energy structure, the closed-loop material recycling scenario can reduce greenhouse gas emissions by approximately 10% through the recycling of steel and plastics alone. Moreover, the transition to shared mobility has the potential to achieve an additional 4%-18% reduction in greenhouse gas emissions by diminishing the final demand for automotive products.

To evaluate the essential role of energy efficiency in achieving net-zero emissions and combating climate change, this comprehensive review was conducted based on a thorough analysis of academic literature, diverse case studies, and industry reports, focusing on key energy efficiency sectors and technological advancements. It begins by outlining global efforts, including the Paris Agreement and the Sustainable Development Goals, which have driven initiatives to enhance energy efficiency across various sectors. The review examines key technological innovations, such as advanced manufacturing, energy-efficient building designs, transportation electrification, and smart grid integration contributing to energy savings and decarbonization. It also discusses policy frameworks, regulatory incentives, and financial mechanisms that encourage energy efficiency. The study provides the detailed outcomes of the different strategies and initiatives, showcasing successful case studies from different regions in transportation, urban planning, power generation, and industry. It illustrates how countries have effectively implemented energy efficiency measures to reduce emissions and meet climate goals. Additionally, the review explores the potential of emerging technologies, including artificial intelligence, big data, and blockchain, to optimize energy management, enhance grid flexibility, and promote further efficiencies. Despite these advancements, the review identifies several key barriers - financial, technological, and behavioral challenges that impede the widespread adoption of energy-efficient practices. Finally, it offers strategies to overcome these obstacles, emphasizing the need for tailored policies, innovative business models, and greater consumer engagement. This review underscores the importance of energy efficiency in achieving a sustainable, net-zero future by synthesizing successful case studies and highlighting emerging solutions.

Offsetting carbon footprints by sequestering carbon through plant biomasses has become a key concern under modern thinking on climate change mitigation. This study aimed to estimate the carbon sequestration capacities of coconut-based gliricidia mixed cropping systems in Sri Lanka and, importantly, to develop an allometric model for non-destructive estimation of carbon. Five major coconut age groups and four major gliricidia age groups were selected to estimate the total carbon stock. The age groups of coconut considered were 10, 20, 30, 40, and 50 years, with corresponding carbon stocks of 22.59, 34.99, 53.13, 63.40, and 66.03 Mg[C]ha^-1, respectively. In gliricidia stands, carbon stocks were 25.53, 46.16, 83.83, and 106.09 Mg[C]ha^-1, respectively, for age groups of 5, 10, 15, and 20 years. It is recommended that gliricidia be introduced as an intercrop in coconut plantations 20 years after the establishment of the latter. For this study, a 30-year-old coconut plantation with a 10-year-old gliricidia intercrop, along with its associated ground cover vegetation and soil carbon stock, were considered the benchmark agroforestry system. In the 30-year-old coconut monocropping system, the total carbon stock was 67.76 Mg[C]ha^-1, which consisted of uniform coconut, 1.24 Mg[C]ha^-1 from ground cover vegetation and 13.39 Mg[C]ha^-1 from the soil carbon stock at a depth of 30 cm. The overall carbon sequestration rate for this monocropping system was 2.25 Mg[C]ha^-1yr^-1 and abated CO₂ in 8.23 Mg[CO₂]ha^-1yr^-1. In the 30-year-old coconut and 10-year-old gliricidia mixed cropping system, the total carbon stock was 114.83 Mg[C]ha^-1, which consisted of uniform coconut and Gliricidia, 1.05 Mg[C]ha^-1 from ground cover plants, and 14.49 Mg[C]ha^-1 from soil carbon stock at a depth of 30 cm. Compared to the coconut monocropping system, the coconut-gliricidia mixed cropping system had a higher carbon sequestration rate of 6.84 Mg[C]ha^-1yr^-1 and abated CO₂ in 25.03 Mg[CO₂]ha^-1yr^-1, which are around three times higher than the monoculture system.

Electricity grids play a crucial role in electricity systems worldwide and will become even more critical as the transition to clean energy advances. In this regard, reducing greenhouse gas (GHG) emissions associated with electricity transmission is crucial to supporting carbon reduction goals and achieving carbon neutrality in light of the escalating climate concerns. This paper aims to quantify the carbon footprint of transmitting electricity through a case study of a transmission line in Brazil (BR-TL). For this purpose, we developed a comprehensive electricity transmission scenario using the ANAREDE software. Additionally, our analysis is derived from data obtained through both primary and secondary sources concerning relevant inputs and outputs considering the construction, operation, and decommissioning stages. As a result, transmitting electricity through the BR-TL transmission line results in 10.89 gCO₂eq. per kWh delivered. Notably, the operation stage is responsible for over 67% of these GHG emissions, predominantly due to energy losses during electricity transmission and associated with the electrical substation transformers. Our results also highlighted the relevance of the construction stage, contributing more than 32% of the carbon footprint, which is mainly linked to GHG emissions resulting from land use change. These findings offer valuable insights for future electricity transmission infrastructure development, aligning with national climate targets and supporting global decarbonization efforts.