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Forestry carbon sink refers to the net income generated by forests, trees and woodlands in the process of absorbing atmospheric carbon dioxide and fixing renewable forest resources. With the rapid development of Chinese economy and accelerating industrialization and urbanization, global climate change has become the focus of attention of all countries. Forest has a strong carbon sink function. The study of forest carbon sequestration and oxygen release value assessment is of great significance for the protection, development and utilization of forest resources and the mitigation of climate change. In this paper, the distributed storage model based on cloud computing architecture was adopted to evaluate the value of forest carbon sequestration and oxygen release. This model can be used to quickly calculate the value of forest carbon sequestration and oxygen release in a certain region, provide data support for forestry carbon sink trading, and provide method reference and scientific basis for forestry carbon sink project accounting. [ABSTRACT FROM AUTHOR]

Forests are the largest pool of carbon in terrestrial ecosystems and are important for climate change mitigation. By analyzing the carbon sequestration process of forest ecosystem, the carbon sequestration amount of forest can be modeled as a nonlinear function, and the mechanism of forest carbon sequestration can be discussed on this basis. The research first introduced the relevant theories of forest carbon sequestration, followed by the preparation of the visualization system construction based on the research area and data sources, and then the construction of the visualization system, and finally carried out the simulation verification. The results show that the system is effective and accurate. [ABSTRACT FROM AUTHOR]

Municipal climate policies tie in closely with sustainable urban development. Land use has far-ranging impacts on carbon emissions from mobility, housing, and consumption; as well as climate resilience, carbon sinks, and biodiversity. While compact city is well-established as the dominant strategy for climate-wise planning, a parallel approach focused on greening and its climate advantages is gaining prominence. However, there is little empirical evidence on how municipal climate policies address the relationship between these often conflicting strategies. This study examines how compacting and greening are motivated and how greening is negotiated in relation to compacting in the six largest cities in Finland. Based on a qualitative content analysis of municipal climate action plans (CAP), we show that the primacy of compacting as a strategy is not questioned, however, the importance of greening is increasingly underlined. We demonstrate that the relationship between compacting and greening policies is framed by three main discourses: 1) compacting while protecting the green, 2) greening the built-up structure for adaptation purposes, and 3) greening as a multifunctional strategy parallel with compacting. The study contributes to the topical debate on the integration of compacting and greening and to the need for cross-sectoral and systemic climate-wise policies in general. • Compacting and greening policies are examined in municipal climate action plans. • Compacting is dominating climate actions, though greening is gaining ground. • The tension between compacting and greening is hidden and specifically reframed. • Three discourses are identified to negotiate greening in relation to compacting. • These are compacting while protecting, adaptive greening and multifunctional greening [ABSTRACT FROM AUTHOR]

Ecological carbon sinks play a crucial role in global carbon cycling and climate mitigation, making their effective management essential. This study develops a novel risk zoning and multifactor analysis framework for ecological carbon sink management in Yunnan Province, China, a region recognized for its ecological diversity and carbon sequestration potential. Our results reveal that high-priority ecological carbon sink zones, mainly in the southwest and western regions, cover 20% of the total area and contain over 60% of the province's carbon stocks. In contrast, high-risk zones, primarily in urbanized regions, show a reduction in carbon sequestration, with emissions exceeding 25.7 million kg due to urban development and landscape degradation. The analysis delineated five distinct risk zones; urgent intervention zones, risk control zones, priority restoration zones, long-term conservation zones, and integrated management zones. Notably, urgent intervention and priority restoration zones, while representing just 9.6% of the area, are critical for protecting over 40% of the carbon sequestration potential. The comprehensive risk zoning framework, combining principal component and canonical correspondence analysis (PCA-CCA), effectively integrates landscape indicators, socio-economic factors, and natural elements. Our innovative, data-driven approach offers strategic insights into managing carbon sinks while balancing ecological integrity and socioeconomic needs, providing a replicable model for ecosystem management. The framework presented in this paper. [Display omitted] • Created a zoning framework combining carbon sink priorities with landscape risks for precise ecological risk management. • Established a zoning matrix for differentiated strategies to enhance carbon sink conservation and mitigate ecological risks. • Integrated PCA and CCA for assessing ecological carbon sinks, revealing impacts from landscape and socio-economic factors. [ABSTRACT FROM AUTHOR]

Effective municipal solid waste (MSW) management is a crucial component for sustainable cities, as inefficient waste disposal contributes to the release of about a billion tons of CO 2 -eq in greenhouse gases (GHG) annually. With escalating global waste generation, there is an untapped opportunity to integrate carbon dioxide removal (CDR) technologies into existing MSW management processes. This review explores current research on utilizing MSW for CDR, emphasizing its potential for both energy generation and carbon sequestration. The investigation covers three waste management practices: landfilling, waste-to-energy (WtE), and biochar production, revealing two paths for carbon sequestration. First, MSW serves as a feedstock in bioenergy with carbon capture and storage (BECCS), acting as a carbon-neutral resource that avoids fossil fuel and energy crop use, reducing GHG emissions and generating value through energy production. Second, direct storage of organic MSW and its derivatives, like biochar, in various carbon sinks allows for extended sequestration, offering a comprehensive approach to address the challenges of waste management and climate change mitigation. Moreover, this review advocates for an extended exploration into several subjects including in-depth analysis of waste, research on MSW-derived biochar recalcitrance across different carbon sinks, and understanding the symbiotic connections with GHG-emitting sectors like agriculture and energy. Finally, this review emphasizes the necessity of conducting life-cycle assessment studies to fully discern the benefits and assess the impacts of any future endeavors exploring the role of MSW in carbon sequestration. [Display omitted] • Municipal solid waste (MSW) is an untapped resource for carbon dioxide removal. • Three strategies to utilize MSW for CO 2 removal include landfilling, waste-to-energy, and biochar production. • Carbon sequestration is achieved through MSW-burial and energy recovery with CCS. • Auditing carbon emissions and LCA are necessary to illuminate the impacts of MSW. [ABSTRACT FROM AUTHOR]

The Intergovernmental Panel on Climate Change (IPCC) ambitious goal of achieving carbon neutrality by 2050 has been embraced by a variety of countries including South Korea. In South Korea, an increasingly vital neutrality strategy is enhancing carbon absorption through land use planning. A key consideration in these strategies is the comprehensive evaluation of carbon sinks present in various land cover categories. These carbon sinks—most notably forests, grasslands, and wetlands—play a critical role in mitigating the effects of climate change by locking carbon dioxide out of the atmosphere. However, forests and grasslands have long been prime avenues for new exurban development. This study analyzes the effects of large-scale development across several key carbon sinks for the Seoul Metropolitan Area of South Korea. Our findings indicate that the key carbon sinks increased from 2007 to 2021. Regardless, urban development has flourished where greenbelts were released, leading to significant depletion of forests, grasslands, and wetlands. However, converting farmland to New Town developments with massive park systems has contributed to an increase in carbon sinks in some parts of the region. In the perspective of South Korea's goals for carbon neutrality, absorption is insufficient. Therefore, it is necessary to reflect the loss of sinks as a cost of sprawl and frame policies to expand storage through afforestation or reassessment of idle, undeveloped land. • A considerable amount of carbon sinks was lost from developing New Towns on greenbelt lands. • Converting farmland to New Towns with large park systems contributed may increase carbon sinks. • Preserving existing natural carbon sinks and creating large urban park systems in new developments could promote sustainable development and climate mitigation. [ABSTRACT FROM AUTHOR]

• Energy & chemical inputs, biogenic emissions, and product substitutions dominate environmental performance of biorefineries. • More transparency needed for product substitution modelling to avoid misleading conclusions. • Biogenic carbon capture use/storage could enhance future climate mitigation efficacy of biorefineries. • Accurate representation of biogenic carbon cycling essential to identify role of biorefineries in net zero strategies. Anaerobic digestion (AD) has gained attention in the last decade as a strategic component of the circular bioeconomy (CBE), and Life Cycle Assessment (LCA) has been used to explore the environmental performance of prospective AD-biorefineries. A detailed review of 76 studies underpinned systematic evaluation of environmental hotspots and LCA modelling challenges for AD-biorefinery configurations. Crops constitute the most frequently used feedstocks, while electricity, bioethanol, digestate, animal feed, additives, and platform chemicals represent the most reported products. Feedstock cultivation, energy and chemical inputs, biogenic emissions, and avoided burdens due to product substitution are the main drivers of environmental performance. However, modelling of product substitution, biogas upgrading, digestate management and biogenic carbon cycling is patchy, inconsistent, and often inadequately evidenced. Prospective and dynamic LCA coupled with transparent scenario analysis could address some of these shortcomings, and better represent, inter alia , the climate mitigation efficacy of carbon capture use and storage technologies integrated into AD-biorefineries. These findings provide a guide for LCA practitioners and researchers engaged in the study of biorefinery systems and other CBE measures. [ABSTRACT FROM AUTHOR]

More than 130 countries and regions have put forward various climate goals, which makes carbon-oriented energy system planning a heated topic. However, these planning studies do not consider the carbon fixation role played by forest carbon sinks (FCSs). To take advantage of the carbon fixation role of FCSs, this paper will develop a carbon-cycle integrated energy hub (CC-EH) model to quantify the economic advantages of FCSs in planning a zero-carbon energy system, where energy flow and carbon flow are both analyzed. A total planning and operating costs minimization with the constraints of CO 2 emissions is proposed as a mixed integer nonlinear programming (MINLP) optimization model and the overall problem is solved based on commercial solver. The proposed model is validated by case studies on six medium to large-size cities in different geographical locations in China. Results indicate that the typical cities in China can fulfill their carbon-neutral commitments by 2060. Throughout the entire planning period, FCSs can offset up to 55.31 % of the total carbon dioxide emissions from urban energy systems. Besides, FCSs achieved by forestation will help the energy system to reduce up to 36 % of the planning cost compared to the case without using FCSs. [Display omitted] • Forest carbon sink (FCS) is modeled considering CO 2 absorption and biomass growth. • FCS is applied to planning through a carbon-cycle integrated energy hub (CC-EH) model. • Coupling of energy system operation and FCS process on an hourly scale is realized. • A power function is introduced to characterize the transition path, and determine the optimal capacity of the CC-EH. • Typical cities in China are taken for case studies to analyze the impact of FCSs on the carbon neutral. [ABSTRACT FROM AUTHOR]

Faced with the multiple challenges of mitigating climate change, controlling air pollution, preserving ecological environments, and promoting economic growth, developing countries need to seek a synergistic development path. The Forest Carbon Sink Project (FCSP) has the potential to support developing countries in achieving these objectives. Currently, empirical research on the synergistic benefits of FCSPs is limited, leading to ongoing debate about their economic and environmental benefits. Therefore, this study uses panel data from 1600 counties in China to provide evidence for the development of FCSPs. Firstly, the study employs a difference-in-differences model to quantitatively assess the causal relationship between FCSP and both economic development and air quality. Furthermore, this study evaluates the potential of FCSP to reduce carbon emissions by setting a scenario of bioenergy planting (BCP). The empirical results show that, compared to non-project counties, FCSP project counties experience a 6.70% increase in real GDP and a 0.90% decrease in PM 2.5 concentration. FCSP generates economic benefits by increasing residents' income, boosting fixed asset investment, and upgrading industrial structure. And it improves air quality by expanding forest area and enhancing vegetation coverage. Scenario simulations show that in the BCP scenario, one project county can yield 23.39 Kt of biomass yearly. Scaling the FCSP to 500 counties would result in an annual reduction of 24.46 Mt. of CO 2 emissions. This amount constitutes roughly 28% of China's CO 2 emission increase in [ 8 ], which was 88 Mt. • Statistical and remote sensing data are combined to build a county-level economic and air quality database in China. • A multi-period DID model is applied to identify the synergistic benefits of Forest Carbon Sink Project (FCSP). • The scenario simulation method is applied to study the possible development paths of FCSP. • Existing FCSPs can synergistically promote economic growth and improve air quality. • Developing bioenergy plantations could allow FCSP to steadily reduce carbon emission in energy sector. [ABSTRACT FROM AUTHOR]

Evapotranspiration (ET) is the main driver of the energy balance partitioning and influences hydrological and carbon cycles at global, regional and local scales. Furthermore, it is the main requirement for developing strategies to improve water use in agriculture. It is known that there is a close relationship between ET and rainfall, especially in tropical environments. Thus, the main goal of this article was to evaluate how ET and its controls (surface conductance - Gs; decoupling coefficient - Ω; Priestley-Taylor parameter - α) respond to the seasonal variability of meteorological forcing in tropical grazed pastures under the climatic conditions of Northeast Brazil. ET was measured using an Eddy covariance (EC) system and analyzed based on data from two agricultural years (2015–2016 and 2016–2017) with negative (-59 mm) and positive (356 mm) rainfall anomaly, respectively. ET exhibited pronounced seasonality, closely aligned with the seasonality of rainfall. Lower daily averages were observed during the dry season in both agricultural years (1.01 ± 0.60 and 0.89 ± 0.44 mm, respectively). On the other hand, higher daily averages were observed during the rainy season (2.44 ± 0.75 and 4.83 ± 0.96 mm, respectively). The Gs patterns and the significant correlation between Gs, Ω, and α (p < 0.01) indicate that surface control prevails over atmospheric control on an annual scale. This finding is confirmed by the annual mean values of Ω (0.27, 2015–2016) and α (0.38, 2016–2017). This relationship is likely induced by a vegetative stomatal control mechanism, which protects the vegetation against excessive water loss during periods of high temperatures and low humidity levels. These findings are crucial for understanding how droughts modulate components of the energy balance and water fluxes in pastures, especially given the intensification of these events. This has implications for the implementation of climate change mitigation policies and soil management. • The seasonality of grazing pasture ET was in line with the seasonality of rain. • On an annual scale, surface control over ET is more relevant than atmospheric control. • VPD is the main controlling factor of surface conductance. [ABSTRACT FROM AUTHOR]

• The 57.00% of the Yangtze River Economic Belt area exhibited a significant increase in annual NPP. • The response of NPP on climate factors was nonlinear, with greater sensitivity to temperature. • The impact of topographic factors on NPP changes had a threshold effect. Net primary productivity (NPP) of terrestrial ecosystems serves as a crucial carbon sink, playing a significant role in mitigating climate change. This study, focusing on the Yangtze River Economic Belt (YREB), a key area for both economic development and ecological conservation in China, evaluates the temporal and spatial changes in regional NPP and its responses to climatic factors against the backdrop of global change. Utilizing long-term NPP and meteorological grid data from 1981 to 2017, we analyzed the annual change patterns of NPP and its linear and nonlinear responses to climatic factors using copula functions. Our findings indicate that 57.00 % of the YREB has experienced a significant increase in NPP, with the most substantial decreases observed in Shanghai and its surrounding areas (P < 0.05). Temperature emerged as the primary climatic driver, positively correlating with NPP changes in over half of the study area (P < 0.05). Moreover, the nonlinear response of NPP to temperature and precipitation underscores the complex interactions between these factors, revealing a sensitivity to temperature variations that surpasses that to precipitation. The study also highlights the influence of solar radiation and topographic factors, with a significant positive correlation between NPP and solar radiation observed in 15.85 % of the area (P < 0.05). The practical significance of these findings lies in their implications for regional ecological management and climate resilience strategies. The positive correlation between temperature and NPP underscores the potential for targeted temperature management to optimize carbon sequestration across the YREB. Furthermore, the identified nonlinear responses and the role of solar radiation and topography in influencing NPP offer valuable insights for the formulation of adaptive strategies that enhance ecosystem productivity and contribute to achieving carbon neutrality goals. By elucidating the dynamics of NPP in response to a range of environmental factors, this study provides a foundation for informed decision-making in ecological conservation and climate change mitigation efforts within the YREB and similar regions globally. [ABSTRACT FROM AUTHOR]

There is growing interest in aligning the wildlife conservation and restoration agenda with climate change mitigation goals. However, the presence of large herbivores tends to reduce aboveground biomass in some open-canopy ecosystems, leading to the possibility that large herbivore restoration may negatively influence ecosystem carbon storage. Belowground carbon storage is often ignored in these systems, despite the wide recognition of soils as the largest actively-cycling terrestrial carbon pool. Here, we suggest a shift away from a main focus on vegetation carbon stocks, towards inclusion of whole ecosystem carbon persistence, in future assessments of large herbivore effects on long-term carbon storage. Failure to do so may lead to counterproductive biodiversity and climate impacts of land management actions. Grasslands are often overlooked global reservoirs of carbon, with soil carbon stocks large enough to compensate for the lower aboveground biomass carbon compared to forests. Due to a larger fraction of ecosystem carbon stored belowground, particularly in more persistent mineral-associated fractions, grazed grassland carbon stocks may be less vulnerable to perturbations than systems with higher aboveground carbon storage. To optimise restoration efforts to achieve both biodiversity and climate mitigation goals, we need to shift away from focusing only on building immediate carbon stocks to include carbon persistence. Herbivores can increase the persistence of ecosystem carbon through redistributing carbon from aboveground vegetation pools vulnerable to disturbances into persistent soil pools. This is particularly important in ancient fire-prone grasslands, but increasing disturbance frequencies across many ecosystems make herbivore restructuring of carbon pools relevant in a wider range of systems. [ABSTRACT FROM AUTHOR]

Trees absorb CO 2 and reduce the impact of GHGs. This paper deals about the carbon uptake dynamics produced by the management of unused lands as tool to help the fulfilment of international commitments on atmospheric CO 2. The paper introduces a new perspective of using the unused lands around Municipalities to compensate the carbon emissions of urban contexts, according to the Sustainable Energy Action Plans as answer to climate change, already approved by the most part of Cities in Europe. The model of the carbon dynamics is based on a genetic algorithm which allows to find the sequence of operations on the unused land in space (portions of the land) and time (rotation of cuts and plantations) to ensure the reaching of a given outcome in terms of carbon captured. The algorithm, therefore, behaves as design support of land management, enriching the literature available for the sector. The paper identifies two possible original scenarios of storing carbon referred as " emergency " and " constant rate "; the first produces after fifty years a maximum carbon uptake of the order of 100 tC/ha while the second a maximum uptake rate of the order of 2 tC/(year ha), after an initial start-up period of 40–50 years. • Mathematical model to evaluate tree growth and carbon sink from reforestation. • Optimization model to manage the carbon uptake in different scenarios. • Forest represents an effective way to remove carbon from atmosphere. • Carbon stock per unit of unused areas around cities and urban area. • Climate mitigation tool suitable by municipality in the context of SECAPs. [ABSTRACT FROM AUTHOR]

• Climate change threatens the carbon sink capacity of forests in Chile. • Industrial plantations do not contribute towards achieving carbon neutrality. • Wildfire emissions exceed the nationally determined contributions mitigation. • Climate actions should diversify including a wider range of nature based solutions. • Conservation and restauration of wetlands can contribute to carbon neutrality. As president of the Climate Change Conference of the Parties, Chile has advocated for developing ambitious commitments to mitigate greenhouse gas emissions to achieve carbon-neutrality by 2050. However, Chile's motivations and ambitious push to reach carbon-neutrality are complicated by a backdrop of severe drought, climate change impacts (i.e., wildfires, tree mortality), and the use of industrial plantations as a mitigation strategy. This has become more evident as widespread and severe wildfires have impacted large areas of industrial plantations, transforming the land-use, land-use change, and forestry sector from a carbon sink to a net carbon source. Consequently, Chile must diversify its climate actions to achieve carbon-neutrality. Nature-based solutions, including wetlands-peatlands and oceans, represent alternative climate actions that can be implemented to tackle greenhouse gas emissions at a national level. Diversification, however, must guarantee Chile's long-term carbon sequestration capacity without compromising the ecological functionality of biodiverse tree-less habitats and native forest ecosystems. [ABSTRACT FROM AUTHOR]

The renewal of old bridges is sometimes restricted to avoid the high carbon emissions caused by materials and construction, which however might not be conductive to climate change mitigation due to their insufficient functions. In order to facilitate the optimization of renewal timing and strategy from the perspective of reducing the comprehensive global warming impacts, we put forward the low-carbon bridge renewal decision method referring to the ideas of consequential life cycle assessment (LCA) and dynamic LCA. In the proposed method, a comparative system boundary matching the bridge renewal characteristics is constructed, where the carbon emission reduction owing to the traffic efficiency improvement by functional updating is incorporated as the low-carbon benefits of renewal, and three types of time-dependent factors, i.e., time-dependent characterization factor, trend factors and changes of traffic demands, are introduced to characterize the influence of renewal timing. The proposed method provided guidance for the renewal of Maogang Bridge, the first long-span cable-stayed bridge in Shanghai. Results illustrate that the global warming impacts of renewal construction activities and the low-carbon benefits from functional updating decrease with the renewal timing. For Maogang Bridge, the rapidly increasing traffic demands inevitably advocated renewal in advance, and the reduction of global warming impacts from emission reduction or carbon uptake could be manifested for renewal in advance. Adopting material recycling in the disposal of old bridge helped reconstructing a new bridge while deconstructing the old one in 2019 becoming the finally selected low-carbon renewal strategy, which is expected to reduce 15.04 kt CO 2 e-2019 compared to the essential renewal in 2050 with the landfill disposal method. The robustness of the strategy choice has been justified, given the variations of analytical time horizon, expected emission trends and repair emissions. In this way, the low-carbon renewal decision method could build a quantitative basis for judging the urgency of functional updating and verifying the low-carbon benefits of immediate concrete recycling in up-coming urban renewals. • Low-carbon bridge renewal decision optimizes renewal timing and strategy. • System boundary is expanded for quantifying benefits from functional updating. • Emission trends and time-dependent characterization factors are explored. [ABSTRACT FROM AUTHOR]

• The nexus between forest-based climate mitigation and health is poorly researched. • This scoping review identified exposure pathways and health co-benefits from forests. • There is potential for synergies between forest management and health benefits. • Interdisciplinary efforts are required for advancement of research and understanding. Climate change is a pressing global challenge with profound implications for human health. Forest-based climate change mitigation strategies, such as afforestation, reforestation, and sustainable forest management, offer promising solutions to mitigate climate change and simultaneously yield substantial co-benefits for human health. The objective of this scoping review was to examine research trends related to the interdisciplinary nexus between forests as carbon sinks and human health co-benefits. We developed a conceptual framework model, supporting the inclusion of exposure pathways, such as recreational opportunities or aesthetic experiences, in the co-benefit context. We used a scoping review methodology to identify the proportion of European research on forest-based mitigation strategies that acknowledge the interconnection between mitigation strategies and human impacts. We also aimed to assess whether synergies and trade-offs between forest-based carbon sink capacity and human co-benefits has been analysed and quantified. From the initial 4,062 records retrieved, 349 reports analysed European forest management principles and factors related to climate change mitigation capacity. Of those, 97 studies acknowledged human co-benefits and 13 studies quantified the impacts on exposure pathways or health co-benefits and were included for full review. Our analysis demonstrates that there is potential for synergies related to optimising carbon sink capacity together with human co-benefits, but there is currently a lack of holistic research approaches assessing these interrelationships. We suggest enhanced interdisciplinary efforts, using for example multideterminant modelling approaches, to advance evidence and understanding of the forest and health nexus in the context of climate change mitigation. [ABSTRACT FROM AUTHOR]

• The Carbon sink capacity of a typical ecotypic county was precisely estimated. • STARFM was employed to estimate interannual NEP at county scale. • The NEP dataset at a 30 m grid scale from 2000 to 2020 was generated. • Spatio-temporal dynamics of NEP in ecotype county were grasped. Net ecosystem productivity (NEP) serves as a pivotal metric for quantitatively elucidating the carbon sink function of terrestrial ecosystems. As a prototype county for the development of an ecological civilization in China, the quantitative estimation of the ecotypic county's ecosystem carbon sink capacity holds immense significance in comprehending the carbon cycle and facilitating the sustainable advancement of regional ecosystems. This study undertook the estimation of NEP in Wuning County from 2000 to 2020, employing a fusion of multi-source remote sensing data, the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM), the improved Carnegie-Ames-Stanford Approach model, and the soil respiration model. Furthermore, we delved into the differences in NEP across various types of land cover. In addition, we employed the Theil-Sen Median trend analysis and Mann-Kendall test to discern the spatio-temporal trends of NEP. The findings indicated the following: (1) The downscaled NDVI generated by STARFM exhibited a remarkable consistency with Landsat NDVI overall (R 2 > 0.95, P < 0.01, 0 < RMSE < 0.1). (2) The gross NEP from 2000 to 2020 in the study area ranged from 542.78 to 720 Gg C, with a multi-year average NEP of 183.84 g C m−2 yr−1. The simulated NEP demonstrated higher accuracy when compared to the measured data (R 2 = 0.79, P < 0.01). (3) The NEP exhibited a spatial pattern characterized by lower values in the central area and higher values in the north and south. Approximately 89.60 % of the total area demonstrated an increase in NEP, with woodland acting as the primary contributor, while 4.50 % of the total area displayed a decreasing trend, predominantly due to the expansion of built-up land. (4) Notable variations in NEP existed among different types of land cover. In terms of vegetation types, the annual average NEP ranked as follows: woodland > grassland > cropland. The application of STARFM has provided valuable insights into the methodology for precise delineation of spatio-temporal dynamics of NEP at the county scale. The outcomes of this study have furnished support for implementing climate change mitigation strategies in ecologically-oriented counties and the bottom-up promotion of China's carbon peaking and carbon neutrality goals. [ABSTRACT FROM AUTHOR]

While carbon sequestration is significant to achieve the net zero and plays an important role in climate change mitigation, urbanization-led land use land cover (LULC) changes are causing significant impacts on the carbon stocks of terrestrial ecosystems. Despite rapid urbanization in Pakistan, previous studies focus solely on localized areas without documenting the influence of urbanization on carbon stock. Hence, insights regarding the carbon storage dynamics (CSD) in response to LULC changes become essential to drive informed decisions and policies. In this context, we leverage high-resolution (30 m) remote sensing data to evaluate and map the grid-level spatial-temporal interactions between urbanization and CSD at the national scale in Pakistan during 1990–2020. To do so, multi-sensor earth observation data are retrieved and processed using the Google Earth Engine and the Integrated Valuation of Ecosystem Services and Tradeoffs models. Our findings indicate that urban areas have expanded exponentially (an increase of ∼1040%), resulting in reduced carbon storage (a decrease of ∼ − 5%). Major cities (e.g., Karachi, Lahore, Faisalabad) showed less urban sprawl while emerging cities (e.g., Rawalpindi and Peshawar) demonstrated higher urban sprawl, primarily due to shifting patterns from rangeland (∼47%) and agriculture (∼35%) to built-up class. Though some afforestation projects have increased forest carbon stocks in the northern region, there is a large north-south spatial heterogeneity in carbon storage loss across Pakistan. The presented high-resolution mapping of CSD over the past three decades advances our understanding of where and how much urbanization has influenced carbon sequestration, nationally. Considering the results, this study emphasizes the need for policies and management approaches that support sustainable urbanization, which does not compromise carbon pools in the country. • Grid level impact of LULC transition and its influence on CSD is mapped. • Transition from green cover to built-up areas led to reduced carbon storage. • Sustainable land management is imperative to maintain carbon storage capacity. [ABSTRACT FROM AUTHOR]

Hundreds of millions of unstable croplands have been underutilized in the time series by repeated cultivation and abandonment, leading to threats to food security and loss of ecological benefits due to frequent disturbance on ecosystem restoration. Understanding unstable cropland and its connections to Sustainable Development Goals (SDGs) is required in the context of increasing food demand and natural conservation. Here, we first investigate the global cropland instability and influencing factors, then simulate the stable utilization of unstable cropland and its ecological effects under different scenarios of maintaining crop production. 395 million hectares of croplands in 173 countries are found under unstable utilization, accounting for 22% of global croplands. Over three-quarters of unstable croplands are distributed in areas with unfavorable agricultural conditions or high conservation value, and countries experiencing high cropland instability share a common characteristic of climatic or terrain constraints on agriculture. According to the simulation results, 141 million hectares or 36% of the unstable croplands could be released for ecological restoration with 3.8 more billion tons of carbon sequestration, while the rest of the unstable croplands could be stably used to increase 3% of global total crop production. This study highlights the importance of managing unstable croplands in climate mitigation and natural conservation as well as reconciling crop production and other SDGs, with guiding significance for land-use management, climate action, and biodiversity conservation. • 395 million hectares of croplands in 173 countries are under unstable utilization. • Three quarters of unstable croplands are constrained by natural and socio-economic factors. • 36% of the unstable croplands could be released for durable ecosystem recovery by simulation. • Projected increase of 3.8 billion tons of carbon sinks with a 3% increase in crop production. • Stabilizing unstable croplands can benefit the SDG win-win by lasting ecosystem recovery. [ABSTRACT FROM AUTHOR]

Marine primary productivity is a critical driver of functioning marine ecosystems, providing a foundation for biological diversity and associated economic productivity, and a key component of the oceanic carbon sink. However, it is largely under-represented within the global marine protected area estate and has been widely ignored in global priority assessments for marine conservation. Using global high-resolution data on marine primary productivity and human cumulative impact to marine systems, more than 18.6 million km² of high productivity-low impact areas in the global ocean were identified. These areas occur across all ocean basins and represent the vast majority of marine provinces and ecoregions. Over 80% of these highly productive waters with low levels of human impact lies within national jurisdictions and yet only 11% of the overall identified area is currently safeguarded within designated marine protected areas or sustainable management initiatives, leaving more than 16.5 million km2 of high productivity-low impact areas without those forms of formal protection. The multifaceted contribution of these areas to preserve biodiversity, support human welfare and help mitigating climate change suggest they are an essential, but currently overlooked, conservation priority for consideration in both global nature conservation and human wellbeing policy fora. ● Over 18 million km2 of highly productive waters with low human impact exist globally. ● These areas exist across all ocean basins and most marine provinces and ecoregions. ● Only 11% of these areas lie within marine protected areas and OECMs. ● Over 15 million km2 of these areas occur in waters of national jurisdiction. ● About 3.5 million km2 of these areas occur in areas beyond national jurisdiction. [ABSTRACT FROM AUTHOR]

The cultivation of deep-rooted vegetation greatly alters the tradeoffs between water and carbon dynamics, yet their impact on microbial carbon sequestration (MCS) remains inadequately documented, particularly in thick vadose zones. This information is crucial for global climate mitigation and ecosystem service enhancement. As such, we collected triplicate samples for each land use type, exploring the abundance and structure of cbbL -harboring microbial communities within 10-m deep profiles under cultivated farmland and two apple orchards of varying ages (n = 72). Our findings indicated a shift from water-dominated (improved water retention at the expense of reduced carbon sequestration) to carbon-dominated benefits (enhanced carbon sequestration at the expense of decreased water retention) in deep soil layers (2–10 m) after the transformation from farmland to apple orchards. Despite the lack of significant differences among the three land use types, the gene abundances and microbial diversity indices reduced with soil depths because of variations in substrates, resources, and microenvironments. The cbbL -harboring microorganisms consisted of 5 phyla, 7 classes, 19 orders, 30 families, and 55 genera, with Proteobacteria as the predominant bacterial phylum. The relative contributions of different genera varied with soil depths, reflecting their distinct survival strategies. The microbial network was positively connected in various soil layers under farmland and apple orchards. Furthermore, the results of correlation, redundancy analysis, and structural equation modeling jointly indicated that plant roots and soil properties, including total nitrogen and organic carbon, governed MCS processes in deep unsaturated zones. Specifically, the low microbial variation between farmland and apple orchards can be attributed to the predominant effects of climatic and pedogenic factors on soil properties, the restricted contribution of plant roots to soil nutrient levels per unit depth, and the adverse effects of plant-induced ecohydrological consequences on root systems and microbial populations. This study offers new insights within thick vadose zones containing deep-rooted plants, thereby contributing to a better understanding of global terrestrial carbon cycle processes. [Display omitted] • Microbial carbon sequestration processes were explored in 10-m deep profiles. • The farmland-to-apple orchards conversion led to water-carbon tradeoffs. • Microbial carbon sequestration differed with depths rather than land use types. • Depth-dependent plant roots and soil nutrients affects carbon sequestration. [ABSTRACT FROM AUTHOR]

[Display omitted] • CO 2 fluxes were measured in three subtropical mangroves for 16 site years. • VPD stress inhibits mangrove productivity during both exposed and inundated periods. • Meteorological factors and VPD have interactive effects on mangrove productivity. • Tides have independent effects on mangrove productivity through salinity changes. • The threshold effect range of VPD stress on mangrove productivity is 2.50–2.95 kPa. Subtropical mangroves have great potential to sequester atmospheric carbon dioxide (CO 2) and thus significantly contribute to climate change mitigation. Meanwhile, the carbon cycling processes in subtropical mangroves are vulnerable to the changing climatic conditions, such as the warming-induced vapor pressure deficit (VPD) increases. However, the impacts of VPD on net ecosystem production (NEP) in subtropical mangroves remain poorly understood due to a lack of detailed assessment of NEP responses to VPD among different mangrove forests over a long-term observational period. In this study, we deployed eddy-covariance systems to measure net ecosystem CO 2 exchange at three subtropical mangrove forests for 16 site-years, comprising two natural and one artificial forests. We employed a state-of-the-art data-driven modeling approach (i.e., Shapley additive explanations (SHAP) framework based on extreme gradient boosting model), which enabled us to explore the interactive effects of meteorological and tidal factors (e.g. salinity) with VPD on the mangrove NEP. We revealed that air temperature, global solar radiation (GR) and wind speed have significant interactions on the response of NEP to VPD stress in subtropical mangroves. For instance, when GR was high, the SHAP interaction values of VPD and GR on NEP decreased with increasing VPD, but when GR was low, the trends were the opposite. However, instead of identifying interactive effects between tidal salinity and VPD on mangrove NEP, we came across potential independent influence of salinity on the same. SHAP analysis was also able to disentangle the impact of VPD from other abiotic drivers. Thus, we evaluated the threshold effect of VPD stress on NEP loss in subtropical mangroves and observed a range of 2.50–2.95 kPa. Above this range, VPD stress leveled off. The subtropical mangrove responses to VPD should be therefore considered in the dynamic global vegetation models to increase the accuracy in carbon cycle simulations in the future. [ABSTRACT FROM AUTHOR]

Non-native species are expanding globally and can alter ecosystem functions, including food web dynamics, community structure and carbon storage. Seagrass are foundation species that contribute a variety of ecosystem services in near-shore coastal ecosystems, including a significant sink of carbon. In the Caribbean, the rapidly expanding non-native Halophila stipulacea has unknown impacts on carbon storage. To investigate the impacts on carbon storage, we quantified organic carbon (C org) content in sediment and seagrass tissues from monotypic H. stipulacea beds, mixed native seagrass beds dominated by Thalassia testudinum and Syringodium filiforme, and unvegetated substrate in St. John, USVI. We found native seagrass-vegetated sediment contained 1.3 times more C org than sediment covered by H. stipulacea , and 1.6 times more C org than unvegetated areas on average. Whereas, H. stipulacea -dominated substrate stored 1.2 times more C org than unvegetated substrate. Likewise, native species contained 2.2 times more aboveground biomass and 6.0 times more belowground biomass than H. stipulacea. Since seagrasses are critical sources of carbon sequestration, our results suggest that invading H. stipulacea is associated with lower carbon stocks which has potential implications for conservation activities and climate change mitigation. [Display omitted] • Non-native species are expanding globally and can alter ecosystem functions. • Our results suggest that invading H. stipulacea is associated with lower carbon stocks. • In the Caribbean, rapidly expanding Halophila stipulacea may reduce carbon storage. [ABSTRACT FROM AUTHOR]

Amid the growing interest on renewables to fight back the current ecological and social crises, crops like oil palm and trees like eucalyptus, with ever-growing and flexibly interchangeable uses as carbon sinks and sources of renewable energy and biomaterials, are praised as climate stewards and vehicles of transition to sustainable development. Hence, flex crops and commodities complexes consolidate within former strongholds and set off to new territories to take down today's crises. Bridging critical and intersectional political economy, ecology and sociology perspectives, and grounded in Guatemala from 2005 onwards, I discuss the implications of the rise of the flex crops and commodities complexes in transitions to sustainability for jobs, labor regimes, and socioecological reproduction. Specifically, the operations of the flex (sugar)cane and (oil) palm complexes in Guatemala involve a predatory form of agrarian extractivism which is driving a process of 'impairing destruction'. This works by means of a job-poor, culturally insensitive, toilsome and unpaid labor-based 'productive' model, and the manufacturing of environmentally and socially toxic landscapes, to fuel a purge of the countryside that leaves nothing and no one, neither friend nor foe, unscathed. However, the purge hits harder on the many working families (and especially on women) who are deemed redundant for the new renewables-led corporate model of sustainable development and climate change mitigation. Many struggle to avoid falling into this outcast condition. But the life purging agro-extractivism of the cane and palm companies both increases and stagnates the reserve army of labor, while simultaneously pushing the relative surplus population to the limits of subsistence. These findings about 'renewable but unlivable' futures call into question business as usual, non-transformative climate stewardship and sustainable development initiatives that constrain the (re)production of fairer and more climate-proof, culturally-sound, and youth-friendly life projects. • Flex crops and commodities complexes are framed as silver bullets against today's socioecological crises. • In Guatemala, the operations of flex (sugar)cane and (oil) palm companies involve a life purging model of agro-extractivism. • This is the outcome of 'impairing destruction' through toxic landscapes and a job-poor, counter-reproductive economy. • The purge strikes harder working families (and women) deemed redundant for the renewables-led corporate order. • Outcomes question non-transformative climate stewardship and sustainable development initiatives. [ABSTRACT FROM AUTHOR]

• Carbon footprint at the UBI consumption level is 4.8 tCO 2 -eq per capita. • UBI carbon footprint is around half of the average carbon footprint in Finland. • Downscaling consumption alone is not enough to achieve sustainable lifestyles. • Additional mitigation solutions are needed alongside downscaling. • At a societal level, downscaling is hard to reconcile with high social security. Human economic activities and following carbon emissions have been recognized to be a real threat to the environment. The current levels of consumption-based carbon footprints in all developed economies grossly exceed the sustainable level. Scientists have concluded that in addition to technological solutions, downscaling of consumption and far-reaching changes in lifestyles will be needed to achieve environmental sustainability. In this study, we provide a tangible real-world example that reveals the scale of the needed change from a perspective of a European welfare state citizen. Universal basic income (UBI) represents an income that is just enough to fulfil basic needs, such as food, shelter, and medication. In our case country, Finland, UBI is in practice at the same level as the income of the lowest income decile. The purpose of this study is to present and analyse the carbon footprints at a consumption level that corresponds to UBI. We compare the carbon footprints at this low-income level to average Finnish carbon footprints and discuss their sustainability in the light of global carbon budgets. We use an input-output approach based on the Finnish ENVIMAT model. The average carbon footprint at the UBI level is 4.8 tCO 2 -eq and it focuses on necessities. It's significantly lower than the average carbon footprint in Finland, 9.4 tCO 2 -eq, but still far from the level compatible with the current climate change mitigation targets. The results emphasize how challenging it is to find true low-carbon solutions for living in affluent countries. Lifestyle changes and technological leaps need to be combined and fostered by legislation. [ABSTRACT FROM AUTHOR]

With emphasis on constructing low-carbon cities, the renovation of old communities highlights the importance of renewing rainwater management facilities. Rain garden is an exceptional Nature-based Solution for rainwater management. When applying them to renovate old communities, the carbon footprint should be considered. This study focused on renovating facilities in the Greater Bay Area and utilized the Energy Expert platform to calculate rain garden carbon footprint with the Life Cycle Assessment. The carbon reduction benefits during the operation were estimated. This study accounting the life cycle carbon footprint of the 5455 m2 rain garden was 1117.42 tCO 2 e. The carbon footprint contribution, from highest to lowest was the end-of-life phase, materials production phase, construction phase, use and maintenance phase. Regarding carbon emission inventory, waste soil landfill, fertilizer acquisition, and waste soil recycling ranked high. Transportation also accounted for a remarkable carbon emission. The rain garden showed great potential for climate change mitigation, with a total and net carbon reduction of 1927.41 and 809.99 tCO 2 e, respectively. To reduce the carbon footprint of the rain garden, we should focus on waste soil treatment and transportation. Recommendations included increasing waste soil recycling, in situ recycling and green transportation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Stand spatial structure plays an important role in the fragile natural secondary forest. • Species diversity have a negative impact in changing restored woodlands, thereby reducing productivity. • Stand spatial structure has a stronger impact on forest carbon sink than species diversity. • Stand spatial structure is a prioritized indicator in the regulation of fragile forest ecosystems. Increasing attention for adjusting forest structural and species diversity has been paid to enhance carbon storage. However, the relative importance of stand spatial structural diversity and species diversity to restored stand carbon stocks remains unclear. To address this issue, we conducted a sample plot setup in the Loess Plateau with the aim of exploring the effects of stand spatial structural diversity and species diversity on forest carbon stocks. Therefore, we determined index parameters for species diversity (Simpson, Shannon-Wiener, and Pielou) and spatial structural diversity (Angular scale, Mingling, Aggregation, and Competition) within the oak forest ecosystem. We examined carbon storage in all vegetation organs and different soil layers. Additionally, we employed a structural equation model to develop a model that illustrates the effects of stand spatial structure and species diversity on ecosystem carbon storage. The results reveal that stand spatial structure and species diversity influence the ecosystem carbon storage through biomass (trees and litter) and soil carbon (0–100 cm). Stand spatial structure exhibits positive direct effects (path coefficients: 0.764 and 0.890), while species diversity shows negative direct effects (−0.320 and −0.206) on biomass and soil carbon, respectively. Finally, the total effect of spatial structure diversity on forest carbon storage surpasses that of species diversity. Therefore, stand spatial structure should be adjusted preferentially during forest management in fragile ecological environment. Our results provide important insights into the climate change mitigation potential associated with the structure-based management of forests. [ABSTRACT FROM AUTHOR]

Carbon emission reduction in China matters to global climate change mitigation. China has been experiencing extensive land changes, which profoundly influence terrestrial ecosystem carbon storage (TECS) and carbon emissions. Scholars have predicted influences of land changes on TECS in China with scenarios obtained from global integrated assessment models (IAMs), which lack national details. Moreover, universally existing variations in land-use intensity have not been considered when estimating influences on TECS. This study simulated changes of land-use intensity of China from 2000 to 2050 using CLUMondo under China-specified policies for sustainable development modeled by a national IAM named Threshold21-China. We proposed a more precise TECS estimation method by distinguishing land-vegetation and land-soil types. Results demonstrated that under scenario with preceding policies, the total TECS can increase by 865.5 Tg C from 2000 to 2050. Through implementing preceding policies, TECS loss by conversions from cultivated land to artificial surfaces can decline by 82 Tg C, and new TECS accumulated by increased and densified forests can increase by 73 Tg C. Mountainous and rapidly urbanizing regions are sensitively influenced and need more restrict land change management policies. This study demonstrates the significance of sustainable development policies for TECS conservation and indicates specific critical regions. • Introducing national IAM into land change simulation. • Considering land-use intensities in land change simulation. • Proposing an improved TECS estimation method. • Estimating influences of land changes on China's TECS. • TECS accumulation could be improved under sustainable policies. [ABSTRACT FROM AUTHOR]

Since the term "blue carbon" was coined by the report of Nellerman et al. (2009) the marine carbon cycle has firmly entered the realm of marine policy alongside its terrestrial neighbour, "green carbon" (Crooks et al., 2018). Many marine policy decisions rely on accurate information concerning the stocks of blue carbon in a region, the annual sequestration rates associated with those stocks and the threats posed to those stocks by human activities, and especially recently by bottom-trawling (e.g., Sala et al., 2021). Hence policy officials are reliant on accurate blue carbon scientific advice. However, at the present moment there is one topic that is contributing confusion to policy-science understanding, and that is the topic of organic vs. inorganic carbon. The aim of this short note is to clarify the differences between these two types of blue carbon and to recommend how they are treated in policy formulation and the provision of scientific advice. [ABSTRACT FROM AUTHOR]

• SOC stocks varied more between geological substrates than between forest types. • Lignin yield differences between forest types were more pronounced on acid soils. • Tree species effects on lignin degradation seem strongly site-dependent. • Lignin chemistry is influenced by both litter input chemistry and edaphic factors. • The relative importance of parent material and litter quality was site-specific. By storing carbon in the soil, forests contribute to climate change mitigation. Edaphic (soil-related) factors, such as soil pH, as well as tree species affect forest carbon cycles, but are difficult to disentangle. We studied how conversion of deciduous stands to mono-culture spruce plantations affected the soil organic matter (SOM) composition along a lithological gradient in the Mullerthal (Luxembourg) and Gaume (south-east Belgium) regions. Parent materials in these regions range from decalcified sands to calcareous marls. A twin plot setup of adjacent deciduous and coniferous stands on the same parent material was used to evaluate the effect of edaphic factors versus litter input differences on SOM composition and soil organic carbon (SOC) stocks. Lignin and cutin/suberin molecular proxies were identified with thermally assisted hydrolysis and methylation (THM), to distinguish litter sources (coniferous vs deciduous and leaf litter vs roots) in the studied stands. In this study, SOC stocks were influenced more by parent material than by forest type. Lignin yield, composition and degradation state were influenced both by litter input chemistry and edaphic context. There appear to be important interaction effects between the two, as the relative importance of parent material and litter quality was site specific. We therefore advice that carbon stock models include data on both vegetation history as well as edaphic context. [ABSTRACT FROM AUTHOR]

Sustainable agricultural and food processing practices are often proposed as attractive strategies enabling food systems to respond to the challenges posed by climate change in terms of adaptation and mitigation. However, information on the actual contribution to climate change provided by sustainable food production systems is lacking in literature. With the intention to contribute to a more informed debate, this study aims at quantify the actual impact on climate of sustainable practices applied to a grape-to-wine system in Italy. The overall budget of greenhouse gas (GHG) fluxes is assessed at wine farm level, from the vineyard to the final bottle of wine, through an integration of methods, including the eddy covariance technique, the life cycle assessment (LCA) and the IPCC guidelines. All the components of the GHG budget have been considered: the (a) biogenic GHG fluxes and the (b) anthropogenic GHG emissions generated for the grape production as well as the (c) carbon stock change due to the vineyard management and the (d) anthropogenic GHG emissions generated by the transformation of grape into wine. At the vineyard level, the overall GHG budget resulted to be close to zero, showing a potential carbon neutrality of sustainable viticulture: the sum of biogenic GHG fluxes (a) and the carbon stock change (c) resulted in a net carbon sink with a potential contribution to climate change mitigation of −0,27 ± 1,11 Mg CO 2 eq year−1 per hectare; while the anthropogenic GHG emissions (b) for the sustainable vineyard management accounted for 0,24 ± 0,05 Mg CO 2 eq ha−1 year−1. The total carbon footprint (b + d) of sustainable wine is 0,79 ± 0,14 kg CO 2 eq per bottle, with 15% attributable to the agricultural phase and 85% to the transformation of grape into wine. These findings indicate that sustainable wine production has in general a lower contribution to climate change. In particular, sustainable practices applied to viticulture can turn the system into a net carbon sink able to totally compensate the anthropogenic emissions for the vineyard management. Therefore, sustainable viticulture allows food production with a potential carbon neutrality without exacerbating climate change. • Sustainable viticulture allows food production with a potential carbon neutrality without exacerbating climate change. • Sustainable viticulture generates biogenic GHG fluxes that turn the agrosystem into a net carbon sink. • Anthropogenic GHG emissions in sustainable vineyard are low and can be totally compensate by the net carbon sink. • The carbon footprint (CF) of sustainable wine is 0,79 ± 0,14 kg CO 2 eq per bottle. • Sustainable wine production has in general a lower contribution to climate change. [ABSTRACT FROM AUTHOR]

Highlights • Spatiotemporal changes of central heating CO 2 emissions at city level are shown. • A high-resolution gridded inventory of heating-related CO 2 emissions is built. • The satellite nighttime light data is used to downscale the city level emissions. • Differences in CO 2 emissions between urban and non-urban areas are discussed. Abstract Energy consumption from central heating has rapidly increased in the cities of the North China Plain (NCP). The increasing use of natural gas in the central heating supply system may have altered the spatial and temporal patterns of CO 2 emissions from central heating, yet the quantitative impacts are poorly understood. Here we detect the spatio-temporal dynamics of CO 2 emissions of central heating from 2012 to 2016 at the prefectural-city level in the NCP region, by using the satellite NPP-VIIRS nighttime light data and a panel regression model to estimate CO 2 emissions on a 5 × 5 km2 grid. We find that despite a slight decrease (2%) in 2014 under the "Natural Gas Utilization Policy", CO 2 emissions continued to grow. Between 2012 and 2016, CO 2 emissions from central heating in the NCP increased from 106 to 121 Tg, although CO 2 emissions declined by 12% in Beijing due to the increasing contribution of natural gas boilers. The gridded CO 2 emissions map shows that over 2012–2016 coal burning is the main driving force of CO 2 emissions in both urban and non-urban regions, despite the increasing fraction of gas-based heating. Our results contribute to city-level policymaking on carbon reduction and climate change mitigation. The high-resolution gridded CO 2 emissions can also be applied in physical models to facilitate carbon cycle studies. [ABSTRACT FROM AUTHOR]

Abstract Assessing the status of important carbon sinks such as seagrass meadows is of primary importance when dealing with potential climate change mitigation strategies. This study examined plant and sediment properties in seagrass meadows (Cymodocea nodosa (Ucria) Asch.) from two high p CO 2 –low pH Mediterranean vent systems, located at Milos (Greece) and Vulcano (Italy) Islands, providing insights on carbon storage potential in future acidified oceans. Contrary to what has been suggested, carbon content (both inorganic and organic) and its surficial accumulation decreased at high p CO 2 –low pH in comparison with controls. The decrease in inorganic carbon may result from the higher solubility of carbonates due to the more acidic conditions. At Vulcano, the seagrass properties (e.g. , leaf area, biomass) appeared negatively affected by environmental conditions at high p CO 2 –low pH conditions and this may have had a detrimental effect on the organic carbon content and accumulation. At Milos, organic carbon decreased at high p CO 2 –low pH conditions, despite the increase in seagrass aboveground biomass, leaf length and area, probably as a consequence of site-specific features, which need further investigation and may include both biotic and abiotic factors (e.g., oligotrophic conditions, decreased sedimentation rate and input of allochthonous material). Results suggest that, in contrast to previous predictions based exclusively on the expected positive response of seagrasses to ocean acidification, carbon storage capacity of the seagrass C. nodosa may not increase at high p CO 2 -low pH conditions. This study emphasizes the need to investigate further the potential alteration in the climate mitigation service delivered by seagrass meadows in acidified oceans. Highlights • Seagrass features differed between control and low pH stations inconsistently in the two vents. • Carbon content and its surficial accumulation decreased at high p CO 2 –low pH conditions. • Carbon storage capacity of the seagrass may not increase at high p CO 2 -low pH conditions. [ABSTRACT FROM AUTHOR]

Abstract Agroforestry, relative to conventional agriculture, contributes significantly to carbon sequestration, increases a range of regulating ecosystem services, and enhances biodiversity. Using a transdisciplinary approach, we combined scientific and technical knowledge to evaluate nine environmental pressures in terms of ecosystem services in European farmland and assessed the carbon storage potential of suitable agroforestry systems, proposed by regional experts. First, regions with potential environmental pressures were identified with respect to soil health (soil erosion by water and wind, low soil organic carbon), water quality (water pollution by nitrates, salinization by irrigation), areas affected by climate change (rising temperature), and by underprovision in biodiversity (pollination and pest control pressures, loss of soil biodiversity). The maps were overlaid to identify areas where several pressures accumulate. In total, 94.4% of farmlands suffer from at least one environmental pressure, pastures being less affected than arable lands. Regional hotspots were located in north-western France, Denmark, Central Spain, north and south-western Italy, Greece, and eastern Romania. The 10% of the area with the highest number of accumulated pressures were defined as Priority Areas, where the implementation of agroforestry could be particularly effective. In a second step, European agroforestry experts were asked to propose agroforestry practices suitable for the Priority Areas they were familiar with, and identified 64 different systems covering a wide range of practices. These ranged from hedgerows on field boundaries to fast growing coppices or scattered single tree systems. Third, for each proposed system, the carbon storage potential was assessed based on data from the literature and the results were scaled-up to the Priority Areas. As expected, given the wide range of agroforestry practices identified, the carbon sequestration potentials ranged between 0.09 and 7.29 t C ha−1 a−1. Implementing agroforestry on the Priority Areas could lead to a sequestration of 2.1 to 63.9 million t C a−1 (7.78 and 234.85 million t CO 2eq a−1) depending on the type of agroforestry. This corresponds to between 1.4 and 43.4% of European agricultural greenhouse gas (GHG) emissions. Moreover, promoting agroforestry in the Priority Areas would contribute to mitigate the environmental pressures identified there. We conclude that the strategic and spatially targeted establishment of agroforestry systems could provide an effective means of meeting EU policy objectives on GHG emissions whilst providing a range of other important benefits. [ABSTRACT FROM AUTHOR]

Abstract Soil organic carbon (SOC) in agricultural lands is vital for global food production and greenhouse gas (GHG) mitigation. Accurate quantification of the change in SOC stocks at regional or national scales, which depends heavily on reliable spatiotemporal carbon (C) input data, remains a big challenge. Here we use the process-based RothC model to estimate change in SOC stocks across Canada for 1971 to 2015, based on calculated annual C flows between cropland and livestock sectors. Total C input to 0–20 cm soils from crops, manure, and biosolids in Canada increased by 81% from 1971 to 2015, which shifted Canadian agricultural lands from a CO 2 source before 1990 (−1.1 Tg C yr−1) to a small sink during 1990–2005 (4.6 Tg C yr−1), and a larger sink thereafter (10.6 Tg C yr−1). The increasing trend of SOC stocks is mainly driven by the increases in crop yield; the enhanced C sink since 2005 reflects increasing C input largely driven by the increasing area and yield of canola. SOC sequestration showed a potential to offset ~34% or more of agricultural GHG emission since 1990. Increasing crop yields and adopting crop mixes that input proportionately more below-ground C, such as canola and oat, showed potential additional opportunity to sequester SOC, estimated at 1.7 Tg C yr−1 for 2016–2030 in Canada. This study illustrates that SOC sequestration is driven largely by plant C inputs, and shows that agronomic measures which augment C input through crop choices and yield-enhancing practices can profoundly benefit climate mitigation strategies. Graphical abstract Unlabelled Image Highlights • Increasing crop production affects agricultural SOC and thereby GHG mitigation. • A whole-system (cropland and livestock) C fluxes analysis was performed. • Total carbon input to 0–20 cm soils increased by 81% from 1971 to 2015 in Canada. • Canadian agricultural land shifted from a CO 2 source before 1990 to a sink thereafter. • Increasing C input through crop choices and yield-enhance benefit SOC sequestration. [ABSTRACT FROM AUTHOR]

Highlights • Carbon storage in Hunan province, China increased from 820 Tg C in 1996 to 1278 Tg C in 2015. • Carbon storages varied from 0.5 Tg to 467 Tg in different forest ecosystems. • Carbon storage showed large spatial heterogeneity in Hunan province. • The mean annual C sequestration was 25.8 Tg yr−1. Abstract Forest ecosystems act as a carbon sink and contribute to climate change mitigation. Research on the spatiotemporal patterns of C storage and density in forest ecosystems is essential to understand the role of forest ecosystems in the C sink and is helpful to select the efficient forest management practice to maximize the C sequestration potential. We quantified the C storage in forest ecosystems in Hunan Province in southern China over two decades by combining forest inventory data with field survey. The C storage in forest ecosystems in Hunan Province increased from 820.2 Tg to 1277.8 Tg over the two decades, with 457.6 Tg (134.4 Tg in vegetation and 323.2 Tg in soil) of C sequestration in the forest ecosystems. Forest C storage increased sharply from 1996 to 2007, but slowly from 2007 to 2015. The mean annual C sequestration was 25.8 Tg yr−1, with 19.0 Tg yr−1 in soil and 6.8 Tg yr−1 in vegetation. The C density in forest ecosystems increased from 110.3 Mg ha−1 in 1996 to 130.8 Mg ha−1 in 2013. C densities varied in forest types, with the highest value in evergreen broadleaved forest ecosystems. The uneven spatial distributions of forest C storage, density, and sequestration in Hunan Province exhibited similar pattern with the highest in the western Hunan and the lowest in the central Hunan. The forest ecosystems in Hunan Province present a significant C sequestration potential (1321.5 Tg, including 1029.2 Tg in biomass C and 292.3 Tg in soil C), given the proportion of the area of young and middle-aged forests (71.3%). To maximize the C sequestration potential of forest ecosystems in Hunan Province, future forest management should focus on the conversion of forest type, the selection of tree species in reforestation, and the prevention of adverse human disturbances in young and middle-aged forests. [ABSTRACT FROM AUTHOR]

[Display omitted] • The conversion of forest to pasture alters soil C and N stocks and distribution in organic matter. • Natural areas and 30-y-old pastures had higher C and N stocks in soil and mineral-associated organic matter. • The sandy texture of the soil contributed to lowering C and N contents and stocks in soil. • C-C 3 losses highest occurred in newer pastures in Dense Cerrado on Acric Petroplinthic Ferralsol. The conversion of Amazon rainforest to grasslands has significant implications for regional and global carbon cycling. The description of affected organic pools and their extent is crucial for accurate prediction of forest-to-pasture conversions. We assessed soil C and N stocks in granulometric fractions of soil organic matter (SOM), particulate organic matter (POM) and mineral-associated organic matter (MAOM), following forest-to-pasture conversion in transition environments of the Brazilian Amazon rainforest and Cerrado biomes. Five study situations (SS) were selected in the Lontra River basin, Tocantins state, Brazil. The situations were established by the association between vegetation and soil classes: OFAr (Ombrophilous Forest on Orthodystric Arenosol); OFPt (Ombrophilous Forest on Petric Plinthosol); DCFr (Dense Cerrado on Acric Petroplinthic Ferralsol); DCAc (Dense Cerrado on Haplic Acrisol); and CSAr (Cerrado Sensu Stricto on Orthodystric Arenosol). In each SS, soil samples were collected in pasture areas with different planting times (between 10 and 30 years), in addition to a reference area with natural vegetation. DCFrP30 (30-y-old pasture) and DCFrNV (natural vegetation area) were statistically similar , both having the highest mean C stocks (0–20 cm: 41.5 ± 6.6 t C/ha; 0–40 cm: 64.6 ± 12.3 t C/ha; 0–60 cm: 85.0 ± 14.8 t C/ha; 0–100 cm: 102 ± 21.8 t C/ha) and N stocks (0–20 cm: 3.5 ± 0.6 t C/ha; 0–40 cm: 5.3 ± 0.9 t C/ha; 0–60 cm: 6.9 ± 1.1 t C/ha; 0–100 cm: 8.1 ± 1.5 t C/ha), especially in MAOM. The highest C-C 3 (δ13C ≈ −27‰) losses occurred in newer pastures of OFAr and CSAr and in DCFr, while C-C 4 (δ13C ≈ −14‰) gains were greater in POM and in 20-y-old pastures of OFPt and DCFr. Our results demonstrate significant change in stocks and distribution of soil C and N in SOM granulometric fractions following the conversion of forest to pasture. Moreover, the results give important insight into the development of strategies focused on the recovery and conservation of environmental quality and mitigation of climate change, particularly for the Amazon region where Cerrado-Amazon rainforest transition areas have been incorporated into agricultural land in recent years. [ABSTRACT FROM AUTHOR]

As interest in natural climate mitigation solutions continues to grow, there is an essential role for coastal and ocean ecosystems ("blue carbon") to play. To meet mitigation targets, however, it is crucial that human actions to protect or restore blue carbon sinks are based on solid science and actionable human management opportunities to increase sinks and reduce emissions from ecosystem loss. Here, we reaffirm the role of coastal wetlands in climate mitigation opportunities. We update the state of the science regarding existing blue carbon pathways and explore expanding the blue carbon opportunities to new systems. Specifically, we analyze new science for those blue carbon pathways we categorize as "emerging" (e.g., management interventions involving macroalgae - both cultivated and wild, tidal flats, and marine sediments) where human action may be able to increase these sinks, but we currently have insufficient information to ensure that their climate mitigation benefit is additional. We revisit those that are "non-actionable" (e.g., management interventions involving calcifying organisms and marine fauna) where the scientific evidence is clear that there is no mitigation benefit, or the science is too uncertain to claim that human action can definitively increase these carbon sinks. With limited funding for climate action, it is critical that efforts focus on projects with the most mitigation potential. Blue carbon management is only one piece in the climate mitigation challenge, but it is an important one. Continued scientific research and investment in developing policy pathways is warranted for these actionable and emerging systems. At the same time, the world must continue to work to decrease emissions rapidly, invest in other natural climate solutions, and scale renewable energy technologies. [ABSTRACT FROM AUTHOR]

• Cities' contribution to global emissions reductions is essential yet uncertain. • A novel dataset is analysed to unveil their progress and expected impact. • Most cities have modest mitigation achievements varying with size and geography. • Cities strongly rely on natural carbon sinks to reach net-zero emissions. • Gaps, barriers, and assistance needs are numerous and call for capacity building. Cities are increasingly becoming critical climate actors. However, their preparedness and ambition in forging climate-neutral futures is hard to ascertain. In this study, we analyse the Expressions of Interest in the Mission on 100 Climate-Neutral and Smart Cities by 2030, an unprecedented dataset of city inputs to 374 different questions on the transition to (net) zero. We i) delineate emissions baselines, accounting methodologies, and inventories' completeness (sectors/sources, carriers, gases), ii) analyse emission trends and cities' capacity to deliver on their climate mitigation commitments, iii) examine the estimated magnitude and origin of residual emissions by 2030 together with the envisioned offsetting strategies, and iv) elucidate gaps, methodological deficiencies, and forms of assistance. Data suggest that if all 362 eligible cities were to reach climate neutrality, approximately 650 MtCO 2 eq would be removed. However, this would require at least a quadruple effort in half the time compared to current mitigation achievements. Beyond the challenge of emissions baselining, cities lack adequate data collection and monitoring systems and show little familiarity with non-technological and technological avenues to tackle harder-to-eradicate emissions. Capacity building will be key across multiple (e.g., technical, financial, operational) domains to turn ambitious mayoral commitments into factual contributions to climate mitigation. [ABSTRACT FROM AUTHOR]

Studies have suggested that some mangrove soils might contribute to wetland methane (CH 4 ) production and emissions, especially when the mangroves are disturbed. CH 4 emissions were measured seasonally from nine locations on two mangrove creeks on Naples Bay in southwest Florida, USA. One of the tidal creeks has been impacted in the past few decades with alteration of upstream watersheds and freshwater inflows; the other creek was an un-impacted reference tidal creek. Our study sites were established along a longitudinal gradient (distance to the creeḱs mouth) with different plant communities and freshwater influences, which were further evaluated by measurements during the dry and wet seasons. CH 4 emission measurements were also performed during the flood and ebb tides (n = 6) to incorporate the influence of water level fluctuations on CH 4 emissions. Additionally, hydroperiods and soil pore water electrical conductivity (EC) as a measure of salinity were measured along the study creeks. Our study showed very small, if not negligible, CH 4 emissions from mangrove soils in this southwest Florida location at all sampling locations and sampling times. Despite our collecting over 1900 methane samples from methane emission chambers, most analyses of rates of change in the chambers showed no methane emissions. Seasonal averages ranged from 0.24 to 1.68 mg CH 4 -C m −2 d −1 (annual average of 0.32 g CH 4 -C m −2 y −1 ). Ironically, the lowest methane emissions were at the end (December–January) of a typical wet season of daily rainfall and were highest in the dry season (March–April) when freshwater inputs from watersheds and precipitation were negligible. Water level fluctuations, freshwater inputs, and plant species composition did not play a significant role in CH 4 emissions. There appeared to be a slight pattern of methane emissions versus air temperature but the relationship was not linear. Combining our results with carbon sequestration rates in a companion study suggested that mangroves in southwest Florida are clearly net sinks of both carbon and radiative forcing and therefore beneficial for mitigating climate warming. [ABSTRACT FROM AUTHOR]

• Most country long-term climate strategies envision reliance on NETs. • Most countries emphasize NETs that enhance natural carbon sinks. • Few countries explicitly envision slowing down short-term mitigation measures. • Countries estimate huge carbon sink potentials despite pervasive uncertainties. • This may set in motion a spiral of delay as uncertainties are sought to be reduced. In order to address the pressing challenge of climate change, countries are now submitting long-term climate strategies to the United Nations Framework Convention on Climate Change (UNFCCC) process. These strategies include within them potential future use of 'negative emissions technologies' (NETs). NETs are interventions that remove carbon from the atmosphere, ranging from large-scale terrestrial carbon sequestration in forests, wetlands and soils, to use of carbon capture and storage technologies. We assess here how NETs are discussed in 29 long-term climate strategies, in order to ascertain the risk that including the promise of future NETs may delay the taking of short-term mitigation actions. Our analysis shows that almost all countries plan to rely on NETs, particularly enhanced use of natural carbon sinks, even as a wide array of challenges and trade-offs in doing so are highlighted. Many strategies call for improved accounting systems and market incentives in realizing future NETs. While no strategy explicitly suggests that NETs can be a substitute for short-term mitigation, most estimate substantial potential for future use of NETs even in the face of acknowledged uncertainties. This, we suggest, may have the consequence of resulting in what we describe here as 'a spiral of delay' characterized by the promise of future NET options juxtaposed with the simultaneous uncertainty around these future options. Our analysis highlights that this inter-connected delaying dynamic may be intrinsic to what we term 'governing-by-aspiration' within global climate politics, wherein the voicing of lofty future ambition risks replacing current action and accountability. [ABSTRACT FROM AUTHOR]

Seagrass meadows deliver a range of ecosystem services, where one of the more important is the capacity to store carbon and serve as sinks for atmospheric carbon dioxide. The capacity of seagrass meadows for carbon storage might, however, be modified and complicated by several factors; one important factor is the possible effects of calcification within the meadows. In tropical areas, seagrass meadows can contain high proportions of calcareous organisms, which through their calcification may cause release of CO 2. To study this aspect of the CO 2 balance within tropical seagrass systems, we investigated the air-water CO 2 flux in seagrass mesocosms with different plant community compositions, i.e. mixtures of seagrass and calcifying macroalgae, having similar overall photosynthetic oxygen evolution rates. The measured CO 2 fluxes changed both in rate and direction over the day and were significantly related to plant community composition. Downward fluxes of CO 2 were found only over vegetation with high proportion of seagrass and in the afternoon, whereas occurrence of calcifying algae appeared to reverse the flow. A partial least squares (PLS) regression model indicated that pH, pCO 2 and dissolved inorganic carbon (DIC) were the primary environmental variables predicting the CO 2 fluxes. Our findings show that algal calcification might partly counteract the carbon sequestration in seagrass meadows. • CO 2 fluxes over the surface were significantly related to plant community composition. • Downward fluxes of CO 2 were found only over vegetation with high proportion of seagrass. • pH, pCO 2 and dissolved inorganic carbon (DIC) were the primary environmental variables predicting the CO 2 fluxes. [ABSTRACT FROM AUTHOR]

Blue carbon ecosystems (BCE) include mangrove forests, tidal marshes, and seagrass meadows, all of which are currently under threat, putting their contribution to mitigating climate change at risk. Although certain challenges and trade-offs exist, remote sensing offers a promising avenue for transparent, replicable, and cost-effective accounting of many BCE at unprecedented temporal and spatial scales. The United Nations Framework Convention on Climate Change (UNFCCC) has issued guidelines for developing blue carbon inventories to incorporate into Nationally Determined Contributions (NDCs). Yet, there is little guidance on remote sensing techniques for monitoring, reporting, and verifying blue carbon assets. This review constructs a unified roadmap for applying remote sensing technologies to develop cost-effective carbon inventories for BCE – from local to global scales. We summarise and discuss (1) current standard guidelines for blue carbon inventories; (2) traditional and cutting-edge remote sensing technologies for mapping blue carbon habitats; (3) methods for translating habitat maps into carbon estimates; and (4) a decision tree to assist users in determining the most suitable approach depending on their areas of interest, budget, and required accuracy of blue carbon assessment. We designed this work to support UNFCCC-approved IPCC guidelines with specific recommendations on remote sensing techniques for GHG inventories. Overall, remote sensing technologies are robust and cost-effective tools for monitoring, reporting, and verifying blue carbon assets and projects. Increased appreciation of these techniques can promote a technological shift towards greater policy and industry uptake, enhancing the scalability of blue carbon as a Natural Climate Solution worldwide. • Blue carbon ecosystems (BCE) play a key role in climate change mitigation. • Remote sensing techniques are cost-effective for monitoring BCE extent and carbon stocks. • A tradeoff exists between spatial resolution and historical coverage of remotely sensed data. • New technologies can facilitate the inclusion of BCE in national inventories and Nationally Determined Contributions (NDCs). • Our decision tree guides the choice of remote sensing methods for monitoring BCE. [ABSTRACT FROM AUTHOR]

• Individual tree level biomass models were fitted for young chestnut plantations. • Plantation age was used to estimate total biomass stored by hectare. • Developed models allow the quantification of biomass storage. • Selection among the equations depend on the available data and prediction objective. Sweet chestnut plantations, irrespective of their main productive orientation (nut or timber production), are key elements of the landscape as well as the cultural heritage of the areas where they are found and provide important functions and services. Hence, recent initiatives have been aimed at extending the area occupied by chestnut trees through forest plantations. Nevertheless, the role of these young chestnut plantations as carbon sinks has been often ignored. The National Inventory of Greenhouse Gas Emissions (GHG) must include estimates of the so-called 'transition forests' during the 20 years following their plantation. In this study, new tools for estimating the total amount of above and belowground biomass stored in young plantations of chestnut were developed to quantify the carbon storage capacity of these plantations. A new set of aboveground biomass and root-shoot ratio models were fitted for individual-tree level based on four different independent variables – root collar diameter, total height, diameter at breast height and crown projection area – and their combinations. The expansion to stand level was based on age, plantation density, productive orientation of the plantation (nut or timber), site index and climate covariates as possible independent variables. At tree level, the best aboveground biomass models were those that include the product of root-collar or breast height diameters and tree height, whereas for root-shoot ratio the best results were obtained when only diameter at breast height is included. At stand level, the most accurate models included age, plantation density and site index for aboveground biomass and only age for root-shoot ratio. The fitted models provided accurate and unbiased predictions of aboveground biomass in the first years of reforestations. The different fitted equations can be used to estimate carbon stocks in young plantations depending on the available data and the objective of the prediction. Individual tree-level equations are recommended when accurate estimates are needed and detailed inventory measurements are available. Stand level equations, only using plantation age, can be an appropriate alternative for use with forest statistics at national scale, although the inclusion of additional covariates can greatly improve the accuracy of the age-based stand level equations. Our results indicated that even low-density nut-oriented chestnut plantations can play a relevant role as C sinks. [ABSTRACT FROM AUTHOR]

Following the Paris agreement in 2015, the European Union (EU) set a carbon neutrality objective by 2050, and so did France. The French agricultural sector can contribute as a carbon sink through carbon storage in biomass and soil, in addition to reducing GHG emissions. The objective of this study is to quantitatively assess the additional storage potential and cost of a set of eight carbon-storing practices. The impacts of these agricultural practices on soil organic carbon storage and crop production are assessed at a very fine spatial scale, using crop and grassland models. The associated area base, GHG budget, and implementation costs are assessed and aggregated at the region level. The economic model BANCO uses this information to derive the marginal abatement cost curve for France and identify the combination of carbon storing practices that minimizes the total cost of achieving a given national net GHG mitigation target. We find that a substantial amount of carbon, 36.2 to 52.9 MtCO 2 e yr−1, can be stored in soil and biomass for reasonable carbon prices of 55 and 250 € tCO 2 e−1, respectively (corresponding to current and 2030 French carbon value for climate action), mainly by developing agroforestry and hedges, generalising cover crops, and introducing or extending temporary grasslands in crop sequences. This finding questions the 3–5 times lower target of 10 MtCO2e.yr−1 retained for the agricultural carbon sink by the French climate neutrality strategy. Overall, this would decrease total French GHG emissions by 9.2–13.8%, respectively (reference year 2019). • Additional carbon storage, net GHG budget, and cost of 8 agricultural practices. • MACC shows abatement potential of 40–60 MtCO 2 e.yr−1 for carbon price 55–250 €.tCO 2 e−1. • Key practices: agroforestry, hedges, cover crops, grasslands in crop sequences. • No "one size fits all strategy" due to heterogeneity across regions and practices. • French agricultural carbon sink potential is 5 times higher than anticipated by the government. [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]

[Display omitted] • A 500 MW e oxy-coal power plant (PP) with CO 2 capture and storage (CCS) was considered. • 5% CO 2 emitted from the PP can be methanized using surplus electricity from renewables. • 80 % replacement by the PP with CCS contributed to lower 0.09 °C of global temperature. • Realistic implementation of coal PPs with CCS using renewable energy was provided. CO 2 -free power plants (PPs) with renewable electricity have promising sustainability implications, but the impact of their widespread use is yet to be determined. Here, the effect of an oxy-coal PP equipped with CO 2 capture, water electrolysis, and CO 2 methanation on electricity efficiency, CO 2 emission rate, CO 2 capture cost, and global surface temperatures (T g) was investigated. By exploiting surplus electricity from renewable sources for electrolysis, we estimated that 5 % of the CO 2 emitted from the coal PP was methanized. The process flow diagram of a 500 MW e decarbonized oxy-coal PP was constructed and its impact on energetic, economic, and environmental values was evaluated. The results were applied to a model of the global carbon cycle to predict T g considering the prospective global population and carbon emission rate (r ff) of fossil fuels by 2050. An 80 % replacement of conventional coal PPs worldwide by decarbonized oxy-coal PPs contributed to reducing r ff by 6.1 Gt CO2 /y in 2050 and lowering T g by 0.09 °C. The additional capital cost to replace 80 % of conventional coal PPs with decarbonized oxy-coal PPs, including associated geological storage costs, was estimated to be $43/t CO2. This study elucidates the promise and limitations of coal PPs designed for CO 2 capture, utilization, and storage (CCUS). Combining CCUS technologies with global warming estimates can be extended to examine the economic and climatic impact of CCUS under various CO 2 emission sources. [ABSTRACT FROM AUTHOR]

Transferring carbon from the atmosphere into terrestrial sinks through carbon sequestration practices (so-called ‘carbon farming’) has been proposed as an important component in Australia’s efforts to mitigate greenhouse gas emissions. We use a Best–worst scaling survey to determine which carbon sequestration practices farmers would be most and least likely to adopt, and what factors were most important in any potential adoption decision. The survey was distributed to dryland cropping and mixed crop-livestock farmers in Western Australia. Farmers ranked improved soil quality and reduced soil erosion as the most important potential co-benefits of carbon farming. Factors discouraging farmers from participating in carbon farming contracts were policy and carbon price uncertainty and the uncertain impact of carbon farming practices on productivity and profitability. Farmers had strong preferences for stubble retention and no-till cropping practices as carbon farming strategies. The practices that farmers preferred least were applying biochar and planting trees. Farm and farmer characteristics, including (lack of) awareness of carbon farming policies and opinions about climate change, influence the potential willingness to adopt different carbon farming practices. Given recent policy uncertainty and farmer preferences revealed in this study, it is important to communicate potential co-benefits (rather than opportunities to earn compensation or carbon credits) to increase farmers’ engagement in carbon sequestration activities. [ABSTRACT FROM AUTHOR]

Lakes and artificial reservoirs present as funnels for global and regional carbon cycling. However, limited information is available about dissolved organic carbon (DOC) bioavailability, especially for its trophic controls and compositional transformations in widely distributed karst waters. Here we examined DOC biodegradation (%BDOC), temperature sensitivity (Q 10 value), nutrients and their stoichiometric ratios, as well as DOC composition over a 28-day laboratory incubation experiment in karst lakes and reservoirs. Fluorescence, Fourier transform infrared (FTIR) and UV–Visible spectroscopy were employed to trace DOC variability. We found that %BDOC ranged between 1.17% and 66.6% (median: 30.1%) at 15 °C and 5.95%–68.5% (median: 31.0%) at 30 °C, respectively. The Q 10 values were mainly distributed between 0.75 and 1.50, suggesting a large amount of degraded substrate with low activation energy. Aquatic DOC and total dissolved nitrogen (TDN) were tightly linked to the %BDOC, whereas significant phosphorus (P) limitation (TDN:TD P > 25) did not induce discernible correlations. Carbohydrates as a dominant contributor to biodegradable DOC (BDOC) largely drove DOC remineralization. The incomplete degradation of humic-like fractions increased the relative abundance of fulvic acid, tyrosine-like and tryptophan-like fractions. A distinctive mode as biological utilization of extreme active and inactive components could be summarized in the karst lakes and reservoirs. These findings hope to supplement special mechanisms of DOC transformation and fate in the context of climate change mitigation for the UN Sustainable Development Goals. [Display omitted] • Carbohydrates as a primary contributor to BDOC in the karst waters. • Large labile fractions caused insignificant BDOC temperature sensitivity. • Low activation energy of the degraded substance invalided nutrient limitation. • Incomplete degradation of humic-like DOC induced molecular weight fluctuations. • Extreme active and inactive components dominated biological utilization of DOC. [ABSTRACT FROM AUTHOR]

• Global forest sector model intercomparison of 81 future pathway scenarios. • Socioeconomic drivers have strongly influence forest sector model estimates. • Global forests could sequester 1.2–5.8 GtCO2e/yr over the next century. • Improved management can increase carbon and harvests without expanding forest area. • Climate policy assessments could better represent forest markets and management dynamics. Deforestation has contributed significantly to net greenhouse gas emissions, but slowing deforestation, regrowing forests and other ecosystem processes have made forests a net sink. Deforestation will still influence future carbon fluxes, but the role of forest growth through aging, management, and other silvicultural inputs on future carbon fluxes are critically important but not always recognized by bookkeeping and integrated assessment models. When projecting the future, it is vital to capture how management processes affect carbon storage in ecosystems and wood products. This study uses multiple global forest sector models to project forest carbon impacts across 81 shared socioeconomic (SSP) and climate mitigation pathway scenarios. We illustrate the importance of modeling management decisions in existing forests in response to changing demands for land resources, wood products and carbon. Although the models vary in key attributes, there is general agreement across a majority of scenarios that the global forest sector could remain a carbon sink in the future, sequestering 1.2–5.8 GtCO2e/yr over the next century. Carbon fluxes in the baseline scenarios that exclude climate mitigation policy ranged from −0.8 to 4.9 GtCO2e/yr, highlighting the strong influence of SSPs on forest sector model estimates. Improved forest management can jointly increase carbon stocks and harvests without expanding forest area, suggesting that carbon fluxes from managed forests systems deserve more careful consideration by the climate policy community. [ABSTRACT FROM AUTHOR]