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• Localized socioeconomic and natural narratives are applied on the regional scale. • Propose ecological zoning management in mountainous agglomerations. • POP, GDP, DEM, and Slope have an inverted U-shaped relationship with carbon storage. • Urbanization expands into the western mountainous under the localized SSP5–8.5 narrative. Ecological carbon storage is critical to climate change mitigation by absorbing CO 2 from the atmosphere. Mountainous ecosystems, crucial carbon reservoirs, are experiencing persistent carbon storage declines, yet management mechanisms targeting such complex terrains remain challenging. Focusing on the Sichuan-Chongqing urban agglomeration, interwoven as mountains and basins, we employed the MPI-coupled (Improved Markov-PLUS-InVEST) model and localized "socio-economic-climatic" narratives to simulate the dynamic evolution of carbon storage over extended periods. Diverse impacts and gradient effects of social, economic, and natural (incl. terrain, climate) drivers on carbon storage are further examined. The findings revealed that: (1) The most carbon storage growth projected from 2030 to 2060 reaches 1.53 %, but of which localized SSP5–8.5 narrative the urbanization encroached upon the undeveloped mountainous, severely impairing carbon sequestration by 81.5Tg. (2) In addition to landscape types, carbon storage exhibits complex spatial responses to economic development, population size, and terrain with an inverted U-shaped relationship. The proposed methodology offers more accurate carbon storage estimates and assists policy-makers in similar terrains to effectively manage the spatial heterogeneity of carbon storage. This study facilitates the implementation of tailored ecological conservation through urban zoning, thus contributing to enhanced subregional climate change mitigation efforts globally. [ABSTRACT FROM AUTHOR]

CO 2 concentration in the atmosphere has crossed an unprecedented level of 420 ppm, causing catastrophic events like climate change. Climate change mitigation via carbon capture is crucial for reducing CO 2 emissions. Among various CO 2 capture technologies, adsorption is considered one of the most efficient and promising techniques. In recent times, substantial research has been conducted on producing cost-effective and efficient adsorbents for CO 2 capture via the thermal and chemical treatments of biomass. In this review, we discuss key scientific results to give broad insight into the recent progress in biomass conversion to activated porous carbon (APC). The effects of various chemical and thermal treatments on the textural properties and CO 2 adsorption capacity of APC are comprehensively discussed. CO 2 adsorption mechanism based on interaction with the surface functionality is thoroughly explained. The economic aspects of APC synthesis and post-combustion CO 2 capture using APC are systematically reviewed. [Display omitted] • Use of biomass based activate porous carbon (APC) for CO 2 capture is reviewed. • CO 2 adsorption mechanism on APC surface is thoroughly explained. • APC surface functionalization via metal doping and heteroatom doping is discussed. • Economics of APC synthesis & large-scale CO 2 capture on APC is critically reviewed. [ABSTRACT FROM AUTHOR]

Bauxite residue or Red Mud (RM) is a by-product from alumina refineries. It has a high pH of 11–13 and accumulates globally at 200 million tons yearly, totalling about 4.6 billion tons. Being an alkaline anthropogenic geomaterial, its adsorption properties and reactivity with acidic gases make it a potential sink for CO 2 and SO X emissions from the aluminium industry. It offers both research challenges and opportunities for its utilisation at an industrial scale. In particular, carbon capture and mineralisation (CCM) within RM has been demonstrated in situ and waste disposal areas through direct air trapping of atmospheric CO 2. The RM-CO 2 system is also operated in ex-situ conditions in various physical states, such as powder, wet cakes, and slurry, with yields of carbonates as CaCO 3 , Na 2 CO 3 , and FeCO 3. Our contribution as a review illuminates significant advancements made and challenges for enhancing the mineral carbonation potential of RM, thereby delineating areas necessitating further exploration. Although, researchers have primarily focused on accelerating the CCM process in RM through slurry carbonation techniques. Recent advancements in filter press technologies have favoured soda recycling and wet cake disposal of RM, creating artificial mountains of RM stacks. With changing disposal trends for RM, it is vital to understand the mechanisms that govern long-term atmospheric CO 2 trapping in RM disposal areas. Recent investigations of techniques, hydrothermal treatment and dual-stage calcification-carbonation methods have expanded the domain of CCM in RM. Given the global need to reduce CO 2 emissions, CCM using RM does offer promising insights on account of its unique physicochemical and mineralogical properties. We, although presume that RM alone will not fully offset the CO 2 emissions of the aluminium industry. Enhanced weathering and mineral carbonation could reduce over 50% of refinery emissions. Uncertainties persist regarding methods of CO 2 sequestration potential and techno-economic feasibility when tested at a field scale. Moreover, contrasting results are revealed, primarily regarding changing disposal trends, variabilities in mineralogy, and limited knowledge of micro-mechanisms of the CCM process in RM. This work elucidates existing knowledge on synthesising CO 2 mineralisation, pathways, and mechanisms under various states associated with leveraging RM as a significant carbon sink in current and future climate change mitigation efforts. [Display omitted] • Illustrates RM mineral carbonation process and mechanistic models for CCM methods (slurry, semi-dry, atmospheric). • CCM potential is studied along with mechanisms using hydrothermal treatment, siderite formation and calcification-carbonation method. • Guidelines for RM sample extraction methods based on its physico-geochemical changes in BRDA with atmospheric CO 2. • Current and future research directions are discussed. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) are one of the most promising functional materials for CO 2 adsorption and transformation owing to their abundant active sites, easily functionalized surface, and highly adjustable pore structure, among others. This review discussed the recent research outputs in the synthesis and catalytic applications of MOFs – based nanocatalysts for CO 2 capture and conversion. The focus was on papers published in the last five years. The different synthetic methods of MOFs and MOF-based nanocomposites were elaborated. More so, the performance of MOFs as adsorbents in CO 2 capture and the proven performance enhancement strategies which include functionalization and compounding with other materials as nanocomposites were discussed in detail. Special emphasis was given to the different transformation routes of CO 2 viz. hydrogenation, photocatalysis, electrocatalysis, photoelectrocatalysis, and chemical fixation. As against what is obtainable in most similar reviews, the review provides insight into the application of MOF-based materials in integrated CO 2 capture and transformation. The work further provides an elaborate discussion of the current challenges and future perspectives. The reported works indicated that these MOF-based materials possessed the required competence for the adsorption and transformation of CO 2 into valuable products, making them excellent choices for practical applications. [Display omitted] • The uncontrolled release of CO2 into the atmosphere is a threat to human survival. • CO2 capture and transformation are one of the significant climate change mitigation options. • MOFs are one of the most promising functional materials for CO2 adsorption and transformation. • MOF synthesis methods are solvothermal, microwave-assisted, mechanochemical, electrochemical, and sonochemical. • CO2 transformation techniques are hydrogenation, photocatalysis, electrocatalysis, photoelectrocatalysis, and chemical fixation. [ABSTRACT FROM AUTHOR]

Plants capture atmospheric carbon dioxide (CO 2) for carbon (C) assimilation through photosynthesis, with the photosynthates stored as plant biomass (above- and below-ground plant parts). The C stored as living biomass is a short-term C sequestration strategy, whereas soil organic carbon (SOC) is a long-term C sequestration strategy. In this regard, plant roots are the primary route of C entry into the SOC pool. Through establishing a recalcitrant SOC pool, long-term sequestration can potentially offset the C losses caused by soil degradation in industrial and pre-industrial eras. Over the next 50–100 years, implementing effective agricultural practices could sequester 80–130 GT (109) C as SOC. Carbon, as the primary elemental component of soil organic matter, plays a significant role in shaping the soil's physical, chemical, and biological properties, ultimately influencing soil biomass productivity. By enhancing crop productivity and biomass production, farmers can increase C sequestration, creating a positive feedback loop that contributes to overall C sequestration. Carbon sequestration has numerous co-benefits, including climate change mitigation, ecosystem health, food security, and farm profitability. Adopting conservation agriculture and site-specific practices and developing crop and pasture genotypes with high yields and C sequestration potential should significantly improve crop productivity and C sequestration simultaneously. This opinion article delves into the nexus between photosynthesis and soil C sequestration, highlighting its significance in enhancing farm productivity while mitigating climate change. [Display omitted] • Good agricultural practices could sequester 80–130 GT (109) C as soil organic carbon (SOC). • Engineering of carbon-concentrating mechanisms can enhance carbon assimilation potential of plants. • Afforestation and restoration of degraded lands can improve SOC besides other ecosystem services. [ABSTRACT FROM AUTHOR]

Understanding sequestration of carbon by coastal ecosystems is central to addressing the role they play in climate change mitigation. To quantify this process, accurate measurements of CO 2 fluctuation, coupled with variations in residence time of coastal water-bodies are required. Nearshore ecosystems, including coastal lagoons, may provide an effective sink for atmospheric carbon dioxide, particularly those containing productive biota such as seagrass. However, the rate and pattern of carbon sequestration in seagrass meadows across a range of environmental settings is still poorly constrained. In this study, we utilize a robust physical tidal model, along with biogeochemical dissolved inorganic carbon (DIC) assessment, to estimate water residence time and net sequestration of atmospheric CO 2 in an intertidal lagoon containing a seagrass (Zostera noltii) meadow. Total alkalinity and pH measurements taken from advected water mass exchanged with the open ocean at inlet boundaries are used to calculate DIC and p CO 2. A predictive model of hydrodynamics provides good approximation of mean water residence time to within 6 h (±3 s.d). Results indicate that during the daytime study period the lagoon is a sink for carbon, having a mean net ecosystem productivity (NEP) of 3.0 ± 0.4 mmol C m−2 hr−1. An equivalent diel NEP range of between 15.23 and −9.24 mmol C m−2 d−1 is calculated based on reported shallow water pelagic respiration rates. Moreover, approximately 4% of DIC availability occurs from atmospheric CO 2 transfer to lagoon water. However, a negative diel rate of −82 ± 81 mmol C m−2 d−1 is found, assuming overnight respiration ascertained from converted Zostera noltii O 2 utilization. We hypothesize that analogous regional nearshore ecosystems provide baseline study sites suitable to elucidate the carbon capture potential of planned, nearby tidal range energy schemes. • Tidal range energy schemes require additional benefits to boost feasibility. • Carbon offsetting could provide an additional income source. • Man-made nearshore lagoons containing seagrass may enhance carbon sequestration. • Results show existing regional lagoons may help elucidate this potential. • High-resolution, multi-disciplinary studies are required to constrain uncertainty. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbon sequestration potential of the clay fraction. • Determination of the carbon saturation deficit of each mineral of the clay fraction. • Identification of the equation for the prediction of carbon sequestration potential. • Identification of land uses with the greatest carbon sequestration potential. The capacity of soil to sequester carbon (C) is a key process that promotes the reduction of CO 2 in the atmosphere. Soils can absorb as much as 20% of anthropogenic carbon emissions, which can contribute to mitigate climate change. This capacity relies on the organo-mineral association, which includes different minerals, Fe and Al oxides, which have a critical soil organic carbon (SOC) sorption surface. Based on an equation of the potential C saturation deficit of fine soil particles (<20 μm/silt and clay fractions) for tropical regions, this study investigated the SOC sequestration potential of the clay fraction for soils in Piracicaba region, São Paulo State, Brazil as influenced by the clay minerals. This potential was fitted to a spatial regression model for soil depths 0–20 cm and 80 to 100 cm. In the surface layer, the sequestration potential was mostly explained by the relative abundance of soil minerals (Kaolinite, Hematite, Goethite and Gibbsite) determined using vis-NIR-SWIR spectroscopy. A direct relationship was observed with Goethite and Gibbsite, indicating that low concentrations would reduce the sequestration potential. At 80 to 100 cm depth, Kaolinite and Hematite explained most variation in SOC sequestration potential. Additionally, the C associated with the mineral fraction and the C saturation potential as a function of minerals were modeled and a strong importance of hematite in the C sequestration and stabilization cycle was identified at both depths. The individual mineral contribution to SOC sequestration potential was also mapped, which identified high contributions of goethite and gibbsite for deep soil layers. The influence of land use on the carbon sequestration potential of minerals was observed, with the greatest potential being found in areas with pasture and cropping mosaics and grassland and forest mosaics, with a high presence of kaolinite and hematite. These minerals have a greater potential for carbon sequestration at greater depths and, therefore, could be critical in climate change mitigation strategies. [ABSTRACT FROM AUTHOR]

Cover crops can contribute to climate change mitigation through enhanced sequestration of atmospheric carbon dioxide into soil organic carbon. Few studies, however, have estimated the total carbon (C) input to soil, i.e. derived both from plant material (shoot and root) and phyllo- and rhizodeposition. Selection of cover crop species should account for multiple objectives, such as C inputs to soil, nitrate leaching reduction and positive residual effects on the following main crop. However, trade-offs between these objectives may occur. The aim of this study was to investigate the performance of the cover crop species winter rye, hairy vetch and oilseed radish, and to assess the ability of mixtures to overcome potential trade-offs. A randomized split-plot field trial was conducted to compare cover crop treatments and a weeded control under high and low soil nitrogen (N) availability. Multiple-pulse labeling with 14C-CO 2 was carried out to trace net cover crop-derived rhizodeposition C. Soil mineral N was measured to 1.5 m depth in autumn, as well as grain and N yield in the subsequent spring barley. Cover crop species accumulated between 1250 and 2580 kg C ha−1, with significantly higher total C input (in shoot, root and phyllo- and rhizodeposits) for the mixtures compared with pure stands of either vetch or radish, while the results for rye were in between. The quantity of C lost via phyllo- and rhizodeposition (qClvPR) showed a significant positive correlation with root C and was highest for the mixtures and rye. The relative ClvPR ranged between 7% and 14% of total cover crop-derived C and tended to decrease under higher soil N availability. All cover crop treatments were able to decrease soil mineral N (0–1.5 m), with radish displaying the highest N leaching reduction potential. Despite substantial differences in cover crop total N uptake and C:N ratios, no significant differences were observed in the subsequent main crop grain or N yields. The mixtures showed the highest total C input and generally a higher or similar mineral N depletion potential than the average of the pure stands, suggesting that cover crop mixtures offer a realistic means for overcoming trade-offs among ecosystem functions. • Winter rye and cover crop (CC) mixtures produced highest total and rhizodeposition C. • Root C was the strongest predictor of rhizodeposition C. • Oilseed radish depleted soil mineral N better than winter rye and hairy vetch. • CC mixtures depleted soil mineral N as well or better than the pure stand average. • Despite dissimilar CC quantity and quality, no crop yield effect of CCs was observed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Climate impacts of e-fuels can vary, depending on the source of electricity, CO 2 and H 2 , and their production technologies. • Today, e-fuels have smaller climate impacts than fossil fuels only if produced with a clean electricity source. • By 2050, stricter climate policies can decarbonize average European electric grid and cut climate impacts of e-fuels by 84%. • Climate change impacts of future e-fuels can be up to 58% lower than those of fossil fuels. • A clean electricity for H 2 production and the use of non-fossil CO 2 are key determinants of the climate benefits of e-fuels. 'E-fuels' or 'synthetic fuels' are hydrocarbon fuels synthesized from hydrogen (H 2) and carbon dioxide (CO 2), where H 2 can be produced via electrolysis of water or steam reforming of natural gas, and CO 2 is captured from the combustion of a fossil or biogenic source or directly from the atmosphere. E-fuels are drop-in substitutes for fossil fuels, but their climate change mitigation benefits are largely unclear. This study evaluates the climate change impacts of e-fuels for aviation by combining different sources of CO 2 and H 2 up to 2050 under two contrasting policy scenarios. The analysis includes different climate metrics and the effects of near-term climate forcers, which are particularly relevant for the aviation sector. Results are produced for European average conditions and for Poland and Norway, two countries with high and low emission intensity from their electricity production mix. E-fuels can either have higher or lower climate change impacts than fossil fuels, depending on multiple factors such as, in order of importance, the electricity mix, the origin of CO 2 , the technology for H 2 production, and the electrolyzer efficiency. The climate benefits are generally higher for e-fuels produced from CO 2 of biogenic origin, while e-fuels produced from CO 2 from direct air capture or fossil fuel combustion require countries with clean electricity to outperform fossil fuels. Synthetic fuels produced from H 2 derived from natural gas have higher impacts than fossil fuels even when coupled with carbon capture and storage, if CO 2 is sourced from fossil fuels or the atmosphere. Climate change impacts of e-fuels improve in the future, and they can all achieve considerable climate change mitigation in 2050 relative to fossil jet fuel, provided that strict climate policy measures are implemented to decarbonize the electricity sector. Under reduced policy efforts, future climate impacts in 2050 of e-fuels from atmospheric or fossil CO 2 are still higher than those of fossil jet fuels with an average European electricity mix. This study shows the conditions to maximize the climate change mitigation benefits of e-fuels, which essentially depend on progressive decarbonization of the electricity sector and on reduced use of CO 2 sourced from fossil fuels. [ABSTRACT FROM AUTHOR]

Improved land stewardship is necessary for climate change mitigation. As such, actions are needed to increase carbon (C) sinks and reduce C emissions from land use activities. Residual materials with fertilizing capacity can be used to reconstruct severely degraded soils and recreate a sustainable vegetation cover, leading to reductions in atmospheric CO 2 levels. We studied the temporal dynamics of CO 2 sequestration potential in soils reconstructed with 1200 Mg ha−1 biosolids along a young chronosequence ranging from 0 to 7 years after initiating reclamation of a decommissioned asbestos mine in southern Québec, Canada. We measured in situ soil CO 2 fluxes, soil C pools and soil physicochemical properties. Since bacterial communities are highly responsive to soil physicochemical properties, we also analyzed both their diversity and community structure. The age since soil reclamation did not have a clear effect on soil properties, but it exerted greater control over soil C fluxes and soil bacterial community diversity and structure. Our results suggest large C fluxes to the atmosphere within the first year following soil reconstruction, but soils constitute a stable C pool thereafter. [ABSTRACT FROM AUTHOR]

• Large uncertainties are associated with the future magnitude and stability of the forest carbon sink. • Business-as-usual management practices might already be close-to-optimum for supporting forest carbon uptake and storage. • Increases in management intensity have the potential to lower forest carbon sequestration and stocking capacity. • Forest management practices are as important as climate change to regulatethe carbon sink and stock size. Forest management practices might act as nature-based methods to remove CO 2 from the atmosphere and slow anthropogenic climate change and thus support an EU forest-based climate change mitigation strategy. However, the extent to which diversified management actions could lead to quantitatively important changes in carbon sequestration and stocking capacity at the tree level remains to be thoroughly assessed. To that end, we used a state-of-the-science bio-geochemically based forest growth model to simulate effects of multiple forest management scenarios on net primary productivity (NPP) and potential carbon woody stocks (pCWS) under twenty scenarios of climate change in a suite of observed and virtual forest stands in temperate and boreal European forests. Previous modelling experiments indicated that the capacity of forests to assimilate and store atmospheric CO 2 in woody biomass is already being attained under business-as-usual forest management practices across a range of climate change scenarios. Nevertheless, we find that on the long-term, with increasing atmospheric CO 2 concentration and warming, managed forests show both higher productivity capacity and a larger potential pool size of stored carbon than unmanaged forests as long as thinning and tree harvesting are of moderate intensity. [Display omitted] [ABSTRACT FROM AUTHOR]

To limit global warming to 1.5 °C, vast amounts of CO 2 will have to be removed from the atmosphere via Carbon Dioxide Removal (CDR). Enhancing the CO 2 sequestration of ecosystems will require not just one approach but a portfolio of CDR options, including so-called nature-based approaches alongside CDR options that are perceived as more technical. Creating a CDR "supply curve" would however imply that all carbon removals are considered to be perfect substitutes. The various co-benefits of nature-based CDR approaches militate against this. We discuss this aspect of nature-based solutions in connection with the enhancement of blue carbon ecosystems (BCE) such as mangrove or seagrass habitats. Enhancing BCEs can indeed contribute to CO 2 sequestration, but the value of their carbon storage is low compared to the overall contribution of their ecosystem services to wealth. Furthermore, their property rights are often unclear, i.e. not comprehensively defined or not enforced. Hence, payment schemes that only compensate BCE carbon sequestration could create tradeoffs at the expense of other important, often local, ecosystem services and might not result in socially optimal outcomes. Accordingly, one chance for preserving and restoring BCEs lies in the consideration of all services in potential compensation schemes for local communities. Also, local contexts, management structures, and benefit-sharing rules are crucial factors to be taken into account when setting up international payment schemes to support the use of BCEs and other nature- or ecosystem-based CDR. However, regarding these options as the only hope of achieving more CDR will very probably not bring about the desired outcome, either for climate mitigation or for ecosystem preservation. Unhalted degradation, in turn, will make matters worse due to the large amounts of stored carbon that would be released. Hence, countries committed to climate mitigation in line with the Paris targets should not hide behind vague pledges to enhance natural sinks for removing atmospheric CO 2 but commit to scaling up engineered CDR. [ABSTRACT FROM AUTHOR]

Afforestation of agricultural land is increasing, partly because it is an important biological method for reducing the concentration of atmospheric CO 2 and potentially mitigating climate change. Rainfall patterns are changing and prolonged dry periods are predicted for many regions of the world, including southern Australia. To accurately predict land-use change potential for mitigating climate change, we need to have a better understanding of how changes in land-use (i.e. afforestation of pastures) may change the soils response to prolonged dry periods. We present results of an incubation study characterising C and N dynamics and the microbial community composition in soil collected from two tree plantings and their adjacent pastures under a baseline and reduced frequency. While the concentration of soil C was similar in pasture and tree planting soils, heterotrophic respiration was significantly lower in soil from pastures than tree plantings. Although there was little difference in the composition of the soil microbial community among any of the soils or treatments, differences in N cycling could indicate a difference in microbial activity, which may explain the differences in heterotrophic respiration between pastures and tree plantings. Soils from pastures and tree plantings responded similarly to a reduction in wetting frequency, with a decrease in microbial biomass (measured as total PLFA), and a similar reduction in heterotrophic respiration from the soil. This suggests that the responses to changes in future wetting cycles may be less dependent on land-use type than expected. [ABSTRACT FROM AUTHOR]

• We introduce biogas-concrete carbon capture utilization, and storage supply chains. • These innovative supply chains have the potential to permanently remove CO 2 from the atmosphere and store it in concrete. • This climate mitigation solution is available today and can be adopted in a seamless manner. • We quantify the trade-offs between supply chains that store CO 2 in concrete and underground. Bioenergy with carbon capture and storage (BECCS) is a carbon dioxide removal (CDR) solution necessary to achieve net-zero-carbon-emissions goals. While the BECCS potential from large industrial emitters has been quantified, the BECCS potential of small emitters, such as biogas facilities, has not been investigated. Moreover, most BECCS solutions rely on the expected availability of large geological storage capacity for future CDR implementation, although the deployment of CO 2 transport and storage supply chains is still a barrier for geological carbon storage ambitions. An alternative opportunity for permanent sequestration of CO 2 is concrete, in which captured CO 2 can be permanently fixed through carbon dioxide mineralization technologies. We describe and discuss this solution by quantifying the potential of a European bioenergy with carbon capture, utilization, and storage (BECCUS) supply chain, which relies on biogenic CO 2 from biogas facilities as a CO 2 source, and on carbon dioxide mineralization in concrete as a permanent CO 2 sink. This solution is available today, can be adopted seamlessly, and does not need economies of scale for its deployment. We find that European biogas facilities produce 24 Mtons of biogenic CO 2 per year, of which 4 Mtons of CO 2 per year are emitted from facilities already upgrading biogas into bio-methane. We estimate that carbon dioxide mineralization in recycled concrete aggregates in Europe could permanently store up to 8 Mtons of CO 2 per year. Despite the limited storage potential, BECCUS supply chains would reduce CO 2 transportation distance and system complexity compared to BECCS supply chains, and would result in a marketable product, namely concrete. Overall, carbon dioxide mineralization in recycled concrete aggregates combines carbon utilization with permanent sequestration, hence contributing to carbon-neutrality goals. [ABSTRACT FROM AUTHOR]

According to the recent IPCC reports, the effects from anthropogenic climate change effects are becoming more serious and actions more urgent. The global mean concentration of CO 2 , the most important Greenhouse Gas (GHG), in the atmosphere is now close to 400 ppm. The most comprehensive research efforts concerning safe levels propose that we should strive to keep the atmospheric concentration of CO 2 below 350 ppm. This is also a more transparent global goal than using effects in the components of the climate system. Most scenarios show that the combustion of fossil fuels will increase in the future, while the development of renewables is still too marginal to stop this growth. The possibility that countries will leave fossil resources underground does not seem realistic. The only options in the short run to halt emissions of CO 2 are the large-scale application of Carbon Capture and Storage (CCS) in combination with increased energy efficiency. In the long run, we have to radically transform our societal metabolism towards greater resource efficiency, where renewables can play a more important role. The main barriers for implementation of CCS on a large scale are not technical, but economic and social. As long as the costs for emitting CO 2 are much lower than implementing CCS technology, there will not be a market-driven development of CCS. A major challenge for CCS will be to achieve wide public acceptance, since this will also affect the future political attitude to it. This will require an open communication about safety aspects early in the planning phase, where it can be shown that safety issues can be handled, even in the event of major leaks of CO 2 . To assume a low probability of accidents is not a feasible way forward in the communication process. The future concerning CO 2 emissions will be determined very much by actions of the biggest emitters. The developed countries have already emitted a large amount of CO 2 and must now take a step forward to show that they are willing to invest in CCS technology. At this stage, it is reasonable to expect developed countries to take a leading role in developing the CCS technology on a large-scale. It is highly probable that developing countries like China will follow this path in the near future, since they have a clear ambition to take a lead in climate change mitigation in the long run and to avoid blame for a deteriorating environment. [ABSTRACT FROM AUTHOR]

The fifth assessment report of the intergovernmental panel on climate change (IPCC) estimated that by 2040 agroforestry would offer high potential of carbon (C) sequestration in developing countries. However, the role of tropical agroforestry in C sequestration and in climate change mitigation has only recently been recognized by United Nations Framework Convention on Climate Change (UNFCCC). This is partly due to the lack of reliable estimates on the sequestration potential in biomass and soil carbon pools over time. The aim of this study was to analyze the changes in the biomass and soil carbon pools of three indigenous agroforestry systems in south-eastern Rift Valley escrapment of Ethiopia using CO2FIX (v. 3.2) model. The agroforestry systems studied were Enset ( Ensete ventricosum )-tree, Enset-coffee-tree, and Tree-coffee systems. To run the model, empirical data collected from 60 farms (20 farms for each agroforestry system) and literature were used as inputs to parameterize the model. Simulations were run over a period of 50 years. Average simulated total biomass C stocks was the highest for Tree-coffee system (122 Mg C ha −1 ), followed by the Enset-coffee-tree (114 Mg C ha −1 ) and Enset-tree system (76 Mg C ha −1 ). The tree cohort accounted for 89–97% of the total biomass C stocks in all the studied systems, and the reminder was shared by Enset and coffee cohorts. The total average simulated total C stocks (biomass and soil) were 209, 286 and 301 Mg C ha −1 for Enset-tree, Enset-coffee-tree and Tree-coffee systems, respectively. The soil organic carbon (SOC) stocks accounted for 60–64% of the total carbon in the studied systems. Model validation results showed that long-term (10–40 years) simulated biomass C stocks were within the range of measured biomass C stocks for Enset-tree and Enset-coffee-tree systems, but significantly differed for the Tree-coffee system. The simulated soil and total C stocks were within the range of measured values for all the three systems. The CO2FIX model accurately predicted the SOC and total C stocks in the studied indigenous agroforestry systems, but the prediction of the biomass C stocks could be improved by acquiring more accurate input parameter values for running the model. [ABSTRACT FROM AUTHOR]

Abstract: Substitution between energy and CO2 intensive materials is a potentially important climate mitigation strategy. We compare buildings with concrete frames and wooden frames concerning their life-time carbon dioxide emissions as well as their total material, energy and carbon dioxide costs. By using consistent energy systems scenarios meeting stringent targets for atmospheric CO2 concentrations we investigate the impact of higher energy and carbon dioxide prices as well as of the availability of carbon capture and storage (CCS) technologies. We find that wooden frames cause lower carbon dioxide emissions given the prevailing energy system, but concrete frames obtain about the same emissions as the wood frame in a system where CCS is not used for wood incineration in the demolishing phase. The net present costs for the different buildings are also affected by the future energy supply system, even though the impact is small, especially compared to the total construction cost. We conclude that it is unclear whether wood framed buildings will be a cost-effective carbon mitigation option and that further analyses of costs should be performed before prescriptive materials policies are enforced in the buildings sector. [Copyright &y& Elsevier]

Abstract: Carbon dioxide capture and storage (CCS) is increasingly seen as a way for society to enjoy the benefits of fossil fuel energy sources while avoiding the climate disruption associated with fossil CO2 emissions. A decision to deploy CCS technology at scale should be based on robust information on its overall costs and benefits. Life-cycle assessment (LCA) is a framework for holistic assessment of the energy and environmental footprint of a system, and can provide crucial information to policy-makers, scientists, and engineers as they develop and deploy CCS systems. We identify seven key issues that should be considered to ensure that conclusions and recommendations from CCS LCA are robust: energy penalty, functional units, scale-up challenges, non-climate environmental impacts, uncertainty management, policy-making needs, and market effects. Several recent life-cycle studies have focused on detailed assessments of individual CCS technologies and applications. While such studies provide important data and information on technology performance, such case-specific data are inadequate to fully inform the decision making process. LCA should aim to describe the system-wide environmental implications of CCS deployment at scale, rather than a narrow analysis of technological performance of individual power plants. [Copyright &y& Elsevier]