A qualitative meta-analysis of carbon offset quality criteria.

Reaching climate neutrality and limiting the global average temperature increase to 1.5 °C, which are the main targets of the Paris Agreement, requires both mitigation measures and offsetting. Despite existing standards to ensure the credibility and effectiveness of carbon offsets, they face challenges associated with their quality. Incorrect replacement factors or baseline values used for the calculations can lead to credits being overestimated. The quality of carbon offsets and its assurance through offsetting standards are addressed in many publications that provide quality criteria that should be fulfilled. However, the abundance of studies and the unclear consistency of quality criteria for carbon offsets make it difficult to draw generalized conclusions. The fragmented understanding of offset quality and its contribution to climate neutrality requires a comprehensive analysis to identify prevailing consensus and areas needing further research. The paper aims to fill this gap by synthesizing existing criteria through a qualitative meta-analysis of the current literature. Consensus and discrepancies in the carbon offset quality criteria and the ratings of the offsetting programs were identified providing a holistic overview. While only the criteria 'additionality' and 'permanence' are consistently addressed in all publications, their definitions and associated aspects vary. Although consensus exists for the criterion 'ex-post', it only appears in 57% of the publications. Differences in definitions are not reflected in the program ratings. The analysis has several challenges, such as accommodating varying study scopes and methods. However, the results highlight the need for a common understanding and provide a baseline reference to enhance the quality assessment of offsets to effectively contribute to climate neutrality.

Defining national biogenic methane targets: Implications for national food production & climate neutrality objectives.

Methane is a short-lived greenhouse gas (GHG) modelled distinctly from long-lived GHGs such as carbon dioxide and nitrous oxide to establish global emission budgets for climate stabilisation. The Paris Agreement requires a 24-47% reduction in global biogenic methane emissions by 2050. Separate treatment of methane in national climate policies will necessitate consideration of how global emission budgets compatible with climate stabilisation can be downscaled to national targets, but implications of different downscaling rules for national food production and climate neutrality objectives are poorly understood. This study addresses that knowledge gap by examining four methods to determine national methane quotas, and two methods of GHG aggregation (GWP100 and GWP*) across four countries with contrasting agriculture, forestry and other land use (AFOLU) sectors and socio-economic contexts (Brazil, France, India and Ireland). Implications for production of methane-intensive food (milk, meat, eggs and rice) in 2050 and national AFOLU climate neutrality targets are explored. It is assumed that methane quotas are always filled by food production where sufficient land is available. Global methane budgets for 1.5 °C scenarios are downscaled to national quotas based on: grand-parenting (equal percentage reductions across countries); equity (equal per capita emissions); ability (emission reductions proportionate to GDP); animal protein security (emissions proportionate to animal protein production in 2010). The choice of allocation method changes national methane quotas by a factor of between 1.7 (India) and 6.7 (Ireland). Despite projected reductions in emission-intensities, livestock production would need to decrease across all countries except India to comply with quotas under all but the most optimistic sustainable intensification scenarios. The extent of potential afforestation on land spared from livestock production is decisive in achieving climate neutrality. Brazil and Ireland could maintain some degree of milk and beef export whilst achieving territorial climate neutrality, but scenarios that comply with climate neutrality in India produce only circa 30% of national calorie and protein requirements via rice and livestock. The downscaling of global methane budgets into national policy targets in an equitable and internationally acceptable manner will require simultaneous consideration of the interconnected priorities of food security and (land banks available for) carbon offsetting.

Online purchasing creates opportunities to lower the life cycle carbon footprints of consumer products.

A major barrier to transitions to environmental sustainability is that consumers lack information about the full environmental footprints of their purchases. Sellers' incentives do not support reducing the footprints unless customers have such information and are willing to act on it. We explore the potential of modern information technology to lower this barrier by enabling firms to inform customers of products' environmental footprints at the point of purchase and easily offset consumers' contributions through bundled purchases of carbon offsets. Using online stated choice experiments, we evaluated the effectiveness of several inexpensive features that firms in four industries could implement with existing online user interfaces for consumers. These examples illustrate the potential for firms to lower their overall carbon footprints while improving customer satisfaction by lowering the "soft costs" to consumers of proenvironmental choices. Opportunities such as these likely exist wherever firms possess environmentally relevant data not accessible to consumers or when transaction costs make proenvironmental action difficult.

Storage management influences greenhouse gas emissions from biosolids.

Biosolids produced by wastewater treatment plants are often stored in stockpiles and can be a significant source of greenhouse gases (GHG). Growing trees in shallow stockpiled biosolids may remove nutrients, keep the biosolids drier and offset GHG emissions through C sequestration. We directly measured methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O) flux from a large biosolid stockpile and two shallow stockpiles, one planted with Salix reichardtii (willow) trees, from December 2009 to January 2011. All stockpiles emitted large annual amounts of GHG ranging from 38 kg CO2-e Mg(-1) dry biosolid for the large stockpile, to 65 kg CO2-e Mg(-1) for the unplanted shallow stockpile, probably due to the greater surface area to volume ratio. GHG emissions were dominated by N2O and CO2 whilst CH4 emissions were negligible (<2%) from the large stockpile and the shallow stockpiles were actually a CH4 sink. Annual willow tree growth was 12 Mg dry biomass ha(-1), but this only offset 8% of the GHG emissions from the shallow planted stockpile. Our data highlight that biosolid stockpiles are significant sources for GHG emissions but alternate management options such as shallow stockpiles or planting for biomass production will not lead to GHG emission reductions.

A study of the evolutionary game of carbon offset involving tourism stakeholders under incentive and constraint mechanisms.

Tourism carbon offsetting is a crucial pathway to achieving peak carbon and carbon neutrality in the tourism industry. Accurately grasping the collaborative evolutionary mechanisms among local governments, tourism enterprises, and tourists is key to promoting the implementation of tourism carbon offsetting. By constructing an evolutionary game model involving local governments, tourism enterprises, and tourists in carbon offsetting, this study uses MATLAB to simulate the evolutionary stable strategies under various conditions. Additionally, it dynamically simulates the collaborative strategies of the three parties under the influence of local government incentive and constraint mechanisms. The results indicate that under strong governmental constraint mechanisms, there is a promotion of active participation in carbon offsetting by local governments, tourism enterprises, and tourists. Incentive policies at certain levels also play a positive guiding role. As incentives increase, local subsidies and intervention costs also rise, leading to an evolution towards less enthusiastic participation among the three parties. Appropriately balanced government incentives and penalties are beneficial in achieving an equilibrium of benefits among multiple stakeholders involved in carbon offsetting, thus helping to attain carbon neutrality goals.

Prospects of Taiwan's solar energy development and policy formulation.

Taiwan lacks energy stock and has been paying great attention to developing renewable energy to improve energy security and sustain economic growth. Solar energy is attractive to Taiwan's government as the recorded radiation is substantial, and a significant amount of fallow land is available for panel installation. This study investigates the potential solar energy production from Crystalline silicon (c-Si) and cadmium Telluride thin-film (CdTe) cell systems, estimates each system's capital requirement, and compares the economic and environmental benefits to explore effective investment strategy. The results show that, on average, the c-Si module could produce 10,644 GWh per year while the CdTe mode would yield a total electricity of about 9365 GWh. The useful life also plays an essential role in the investment requirement. With a 30-year useful life, the systems can reduce the annualized installation and maintenance cost to about NT$3.16 billion. In terms of offset efficiency, every MWh produced would result in at least 13.63-15.49 metric ton of carbon emission offset, and the offset value per GWh can be up to NT$5.77 million, which provide attractive economic incentives to energy suppliers. We point out that the acquisition of low-cost financing sources such as green bonds, as well as the improvement of current emission trading systems (ETS), would greatly benefit solar energy development.

Spatiotemporal characteristics and determinants of agricultural carbon offset rate in China based on the geographic detector.

This paper attempts to explore the spatiotemporal variation characteristics of the agricultural carbon offset rate (ACOR) and the reasons that shape its differentiation characteristics in China. To achieve this objective, the Dagum Gini coefficient, kernel density estimation, and geographic detector model are employed in this study. The results show that there are some differences in ACOR among regions in China. Interregional differences are the main source of their overall variation. Excluding the spatial conditions, the ACOR of each province in the sample period shows low mobility characteristics. Considering the spatial conditions, there is convergence in the lower-middle neighborhoods. The three-year lag period did not significantly affect the interaction of ACOR between regions under the accession time horizon. At the aggregate level, the spatial and temporal divergence in China's ACOR is driven by urbanization rate, agricultural fiscal expenditure, and rural education level. As for the regional level, the scale of household farmland operation plays a greater role in determining the spatiotemporal variation of the eastern and central regions' ACOR. While urbanization rate is more determinant for the western region, the interaction between any two factors has significantly higher explanatory power for the spatial and temporal variation of ACOR than the single factor.

Carbon offset potential of biochar based straw management under rice- wheat system along Indo-Gangetic Plains of India.

The Paris Agreement goal of a net-zero equation will require decarbonization technologies in agriculture. Agri-waste biochar offers huge potential for carbon abatement in agricultural soils. The present experiment was carried out to compare the effects of residue management, viz., no residue (NR), residue incorporation (RI), and biochar (BC), as well as nitrogen options for emission reduction and carbon capture under the rice-wheat cropping sequence (RWCS) of the Indo-Gangetic Plains (IGP), India. After two cycles of cropping pattern, the analysis revealed that the biochar application (BC) reduces the RWCS's annual CO2 emissions by 18.1 % over residue incorporation (RI), while CH4 and N2O emissions were reduced by 23 % and 20.6 % over RI and 11 % and 29.3 % over no residue (NR), respectively. The application of biochar-based nutrient composites with rice straw biourea (RSBU) at 100 % and 75 % significantly reduced greenhouse gases (CH4 and N2O) compared to commercial urea at 100 %. The global warming potential of cropping systems recorded with BC was 7 % and 19.3 % lower than NR and RI, respectively, while 6-15 % under RSBU over urea 100 %. The annual carbon footprint (CF) under BC and NR decreased by 37.2 % and 30.8 % over RI, respectively. The net CF under residue burning was estimated to be the highest (132.5 Tg CO2-Ce), followed by RI (55.3 Tg CO2-Ce), showing net positive emissions; however, net negative emissions were found under a biochar-based system. The estimated annual carbon offset potential of a complete biochar system over residue burning, incorporation, and partial biochar as calculated was 189, 112, and 92 Tg CO2-Ce yr-1, respectively. A biochar-based approach to managing rice straw had great carbon offset potential through a large drop in greenhouse gas emissions and an improved soil carbon pool under the rice wheat system along the IGP, India.

A game-theoretic approach to designing carbon regulations in a duopoly freight transportation market: Road and multimodal road-rail competitive systems.

Since the transportation industry produces remarkable carbon emissions worldwide, governments aim to curb these emissions by implementing different carbon regulations. However, little is known regarding how the heterogeneity of transportation systems should be exploited to design carbon regulations. To fill this research gap, the present article formulates carbon cap-and-trade and carbon offset regulations to reduce total carbon emissions produced by road and multimodal road-rail freight transportation systems (FTSs) in a duopoly market; the latter is regarded as a green, energy-efficient transportation mode. A novel procedure is suggested to allocate initial carbon caps that is a hybrid of both benchmark and grandfathering methods. The procedure allows the government to exploit the energy efficiency of the multimodal system, when targeting a reduction of total carbon. Then, a game-theoretic approach is adopted to implement the mentioned carbon regulations. A government, as a Stackelberg leader, maximizes a social welfare function containing economic, social, and environmental dimensions. Under the cap-and-trade regulation, a Nash bargaining process is proposed to trade carbon permits between the FTSs, as the followers, for updating their initial caps. The equilibrium outputs of the two mentioned carbon regulations and a carbon tax regulation are compared. The findings based on an experimental analysis suggest that the cap-and-trade (carbon offset) is the optimal and energy-efficient regulation from the social (economic or environmental) perspective. In terms of policy implications, our findings indicate that the development of a marketplace infrastructure for trading carbon permits is not justifiable under the economic and environmental perspectives of the government.

Blue carbon assessments of seagrass and mangrove ecosystems in South and Southeast Asia: Current progress and knowledge gaps.

Coastal blue carbon ecosystems can be an important nature-based solution for mitigating climate change, when emphasis is given to their protection, management, and restoration. Globally, there has been a rapid increase in blue carbon research in the last few decades, with substantial investments on national scales by the European Union, the USA, Australia, Seychelles, and Belize. Blue carbon ecosystems in South and Southeast Asia are globally diverse, highly productive and could represent a global hotspot for carbon sequestration and storage. To guide future efforts, we conducted a systematic review of the available literature on two primary blue carbon ecosystems-seagrasses and mangroves-across 13 countries in South and Southeast Asia to assess existing national inventories, review current research trends and methodologies, and identify existing knowledge gaps. Information related to various aspects of seagrass and mangrove ecosystems was extracted from 432 research articles from 1967 to 2022. We find that: (1) blue carbon estimates in several countries have limited data, especially for seagrass meadows compared to mangrove ecosystems, although the highest reported carbon stocks were in Indonesia and the Philippines with 4,515 and 707 Tg within mangrove forest and 60.9 and 63.3 Tg within seagrass meadows, respectively; (2) there is a high difference in the quantity and quality of data between mangrove and seagrass ecosystems, and the methodologies used for blue carbon estimates are highly variable across countries; and (3) most studies on blue carbon stocks are spatially biased towards more familiar study areas of individual countries, than several lesser-known suspected blue carbon hotspots. In sum, our review demonstrates the paucity and variability in current research in the region, and highlights research frontiers that should be addressed by future research before the robust implementation of these ecosystems into national climate strategies.

Spatiotemporal pattern of carbon productivity and carbon offset potential in Chinese counties.

This study used panel data for 2166 county-level units in China between 2000 and 2017 to characterize carbon productivity's temporal and spatial evolution in Chinese counties. The "catch-up effect" of carbon offsets between counties was examined, and this was used to measure the carbon offset potential and analyze its spatial differences. The results indicated that: (1) China's carbon productivity increased from 2000 to 2017; carbon productivity in eastern China was the highest, and carbon productivity in northeast China was the lowest. A polarization to unipolarization evolutionary trend was evident. (2) Considering the spatial differences in carbon productivity, the overall difference in carbon productivity in China from 2000 to 2017 first decreased and then increased; the contribution rate of differences between cities and counties to the overall difference was relatively stable, at around 39.88 %. The contribution rate of the differences between zones to the overall difference was the lowest, remaining stable at around 2.49 %. (3) In terms of the spatial distribution of the carbon offset potential, the eastern region exhibited the highest average carbon offset potential. The carbon offset potential of China exhibited a "high in the north and low in the south; low in the west and high in the east" spatial pattern.

Economic and environmental sustainability analysis of seaweed farming: Monetizing carbon offsets of a brown algae cultivation system in Ireland.

This paper examines the economic and environmental costs of seaweed cultivation (Alaria esculenta) in Ireland and evaluates the potential revenue made on the voluntary carbon offset market (VCOM). The life cycle assessment (LCA) results revealed the cultivation equipment with the polypropylene used for the cultivation lines contributes the highest share of impacts due to their replacement rate. This study suggests long-term employment of farm infrastructure and increased seaweed yield could enhance the environmental sustainability of the system. Moreover, life cycle costing (LCC) indicates the seaweed farm in Ireland is economically feasible over a 20-year lifespan. However, the revenue generated on the VCOM from the seaweed carbon assimilation was minimal, contributing to only 5% of the revenue. This study concludes that further development of the seaweed market with stabilized biomass prices and producing a range of viable products from seaweed biomass will be a major factor in the economic sustainability.

Exploring development and evolutionary trends in carbon offset research: a bibliometric perspective.

This study proposes a bibliometric measure to visualize and analyze the research status and development trend of carbon offset based on 1,581 articles over the period 1900-2019. The main findings include (1) carbon offset research turned into a rapid growth after 2009; (2) environmental studies, environmental science, economics, and energy fuels are the top four research domains in publication; (3) Energy Policy, Ecological Economics and Science are the top three journals in terms of citation impact; (4) climate change, impact, emission, CO2 emission, and policy are shown to be the most frequently used keywords; (5) the top 10 cited articles cover the following five essential aspects: individual carbon offset behavior; forest and land carbon offset; transportation carbon offset; international trade carbon offset; and eco-system service-related carbon offset; (6) eight research hotspots were identified including forest carbon sequestration program, understanding carbon and uncertainty market, policy design, biomass development, Chinese province, increasing adoption, and ecosystem service commodification. These findings suggest that the carbon offset research has been evolved from the theoretical exploration at the early stage to a more diversified conversion of research outputs at the practical level in recent years. Interdisciplinary research towards individual and organizational carbon offset behaviors in a broader context of socio-economic development and cooperation among various agents is the emphasis and direction for future study.

Carbon offset market methodologies applicable for coastal wetland restoration and conservation in the United States: A review.

Coastal wetlands have been valued for a variety of ecosystem services including carbon sequestration and long term storage. The carbon sequestered and stored in coastal habitat including mangroves, salt marshes, and seagrass beds is termed as blue carbon. However, these systems are threatened mainly due to sea level rise, limited sediment supply, edge erosion, and anthropogenic influences. These habitats require restoration and conservation to continue providing ecosystem services. The incentive for emission reductions, referred to as carbon offsets, is well established for other ecosystems like forestry and agriculture. Some blue carbon offset methodologies or protocols have been certified by various voluntary carbon markets; however to date, a few wetland restoration carbon offset in the US has been transacted. Thus, the goal of this paper is to discuss the existing carbon market and carbon market methodologies applicable to coastal wetland restoration and conservation in the US. Currently, four wetland carbon offset methodologies have been approved in the carbon market. These methodologies are site and/or project-specific depending on the type of the wetlands, vulnerability to loss, and restoration need. The appropriate carbon stock and Green House Gas (GHG) emission assessment is the basis of determining carbon offsets. Simplification of the existing methodologies and development of new site and project-specific methodologies could potentially help to realize blue carbon offsets in practice. The slowly growing demand for carbon offsets in the carbon market could potentially be fulfilled from the blue carbon pool. While this carbon offset is in the early stages, this review may help the inclusion of carbon offset component in the coastal restoration and conservation projects in United States and potentially across the globe.

High resolution remote sensing for reducing uncertainties in urban forest carbon offset life cycle assessments.

BACKGROUND: Urban forests reduce greenhouse gas emissions by storing and sequestering considerable amounts of carbon. However, few studies have considered the local scale of urban forests to effectively evaluate their potential long-term carbon offset. The lack of precise, consistent and up-to-date forest details is challenging for long-term prognoses. Therefore, this review aims to identify uncertainties in urban forest carbon offset assessment and discuss the extent to which such uncertainties can be reduced by recent progress in high resolution remote sensing. We do this by performing an extensive literature review and a case study combining remote sensing and life cycle assessment of urban forest carbon offset in Berlin, Germany. MAIN TEXT: Recent progress in high resolution remote sensing and methods is adequate for delivering more precise details on the urban tree canopy, individual tree metrics, species, and age structures compared to conventional land use/cover class approaches. These area-wide consistent details can update life cycle inventories for more precise future prognoses. Additional improvements in classification accuracy can be achieved by a higher number of features derived from remote sensing data of increasing resolution, but first studies on this subject indicated that a smart selection of features already provides sufficient data that avoids redundancies and enables more efficient data processing. Our case study from Berlin could use remotely sensed individual tree species as consistent inventory of a life cycle assessment. However, a lack of growth, mortality and planting data forced us to make assumptions, therefore creating uncertainty in the long-term prognoses. Regarding temporal changes and reliable long-term estimates, more attention is required to detect changes of gradual growth, pruning and abrupt changes in tree planting and mortality. As such, precise long-term urban ecological monitoring using high resolution remote sensing should be intensified, especially due to increasing climate change effects. This is important for calibrating and validating recent prognoses of urban forest carbon offset, which have so far scarcely addressed longer timeframes. Additionally, higher resolution remote sensing of urban forest carbon estimates can improve upscaling approaches, which should be extended to reach a more precise global estimate for the first time. CONCLUSIONS: Urban forest carbon offset can be made more relevant by making more standardized assessments available for science and professional practitioners, and the increasing availability of high resolution remote sensing data and the progress in data processing allows for precisely that.