Eco-toxicological and climate change effects of sludge thermal treatments: Pathways towards zero pollution and negative emissions.

The high moisture content and the potential presence of hazardous organic compounds (HOCs) and metals (HMs) in sewage sludge (SS) pose technical and regulatory challenges for its circular economy valorisation. Thermal treatments are expected to reduce the volume of SS while producing energy and eliminating HOCs. In this study, we integrate quantitative analysis of SS concentration of 12 HMs and 61 HOCs, including organophosphate flame retardants (OPFRs) and per- and poly-fluoroalkyl substances (PFAS), with life-cycle assessment to estimate removal efficiency of pollutants, climate change mitigation benefits and toxicological effects of existing and alternative SS treatments (involving pyrolysis, incineration, and/or anaerobic digestion). Conventional SS treatment leaves between 24 % and 40 % of OPFRs unabated, while almost no degradation occurs for PFAS. Thermal treatments can degrade more than 93% of target OPFRs and 95 % of target PFAS (with the rest released to effluents). The different treatments affect how HMs are emitted across environmental compartments. Conventional treatments also show higher climate change impacts than thermal treatments. Overall, thermal treatments can effectively reduce the HOCs emitted to the environment while delivering negative emissions (from about -56 to -111 kg CO2-eq per tonne of sludge, when pyrolysis is involved) and producing renewable energy from heat integration and valorization.

A global daily evapotranspiration deficit index dataset for quantifying drought severity from 1979 to 2022.

Droughts cause multiple ecological and social damages. Drought indices are key tools to quantify drought severity, but they are mainly limited to timescales of monthly or longer. However, shorter-timescale (e.g., daily) drought indices enable more accurate identification of drought characteristics (e.g., onset and cessation time) and help timely potential mitigation of adverse effects. Here, we propose a dataset of a daily drought index named daily evapotranspiration deficit index (DEDI), which is produced for global land areas from 1979 to 2022 using actual and potential evapotranspiration data. Validation efforts show that the DEDI dataset can well identify dry and wet variations in terms of spatial patterns and temporal evolutions when compared with other available drought indices on a daily scale. The dataset also has the capability to capture recent drying trends and to detect ecology- or agriculture-related droughts. Overall, the DEDI dataset is a step forward in facilitating drought monitoring and early warning at higher temporal resolution than other compared existing products.

An action plan for the agri-food sector at the time of the climate and biodiversity crises.

Agriculture is responsible for about one third of global greenhouse gas emissions and it is the primary driver of habitat destruction. A paradigm shift embracing changes in lifestyles, agricultural practices, and policies is required to realize a sustainable transition in the agri-food sector.

Upgrading protected areas can improve or reverse the decline in conservation effectiveness: Evidence from the Tibetan Plateau, China.

Protected areas (PAs) are considered essential for maintaining biodiversity. Several governments would like to strengthen the management levels of their PAs (as shorthand for a hierarchy in PA administrative governance) to consolidate their conservation effectiveness. This upgrade (e.g., from provincial- to national-level PAs) means stricter protection and increased funds for PA management. However, confirming whether such an upgrade can produce the expected positive outcomes is key given limited conservation funds. Here, we used the Propensity Score Matching (PSM) method to quantify the impacts of upgrading PAs (i.e., from provincial to national) on vegetation growth on the Tibetan Plateau (TP). We found that the impacts of PA's upgrading can be divided into two impact types: 1) curbed or reversed declines in conservation effectiveness and 2) rapidly increased conservation effectiveness before the upgrade. These results indicate that the PA's upgrading process (including the pre-upgrade operations) can improve PA effectiveness. Nevertheless, the gains did not always occur after the official upgrade. This study demonstrated that in comparison to other PAs, those with more resources or stronger management policies were more effective.

Climate change mitigation potentials of biofuels produced from perennial crops and natural regrowth on abandoned and degraded cropland in Nordic countries.

Bioenergy expansion is present in most climate change mitigation scenarios. The associated large land use changes have led to concerns on how bioenergy can be sustainably deployed. Promising win-win strategies include the production of perennial bioenergy crops on recently abandoned cropland or on cropland prone to land degradation, as perennial crops typically reduce soil erosion rates. Natural vegetation regrowth is an alternative nature-based solution that can also co-deliver negative emissions and other environmental benefits. In this study, we explore the potential to deploy bioenergy crops in Nordic countries (Norway, Sweden, Finland, and Denmark) on abandoned cropland and on cropland threatened by soil erosion and compare the achievable climate change mitigation benefits with natural regrowth. We found 186 thousand hectares (kha) of abandoned cropland and 995 kha of cropland threatened by soil erosion suitable for bioenergy crop cultivation. The primary bioenergy potential in the region is 151 PJ (PJ) per year, corresponding to 67-110 PJ per year of liquid biofuels depending on biorefinery technology. This has a climate change mitigation potential from -6.0 to -17 megatons of carbon dioxide equivalents (MtCO2eq) per year over the first 20 years (equivalent to 14-40% of annual road transport emissions), with high-end estimates relying on bioenergy coupled to carbon capture and storage (BECCS). On the same area, natural regrowth can deliver negative emissions of -10 MtCO2eq per year. Biofuel production outperforms natural regrowth on 46% of abandoned cropland with currently available biorefinery technologies, 83% with improved energy conversion efficiency, and nearly everywhere with BECCS. For willow windbreaks, improved biorefinery technology or BECCS is necessary to ensure the delivery of larger negative emissions than natural regrowth. Biofuel production is preferable to natural regrowth on 16% of croplands threatened by soil erosion with the current biorefinery technology and on 87% of the land area with BECCS. Without BECCS, liquid biofuels achieve larger climate benefits than natural regrowth only when bioenergy yields are high. Underutilized land and land affected by degradation processes are an opportunity for a gradual and more sustainable bioenergy deployment, and local considerations are needed to identify case-specific solutions that can co-deliver multiple environmental benefits.

Achieving the Sustainable Development Goals in the post-pandemic era.

The COVID-19 pandemic continues to pose substantial challenges to achieving the Sustainable Development Goals (SDGs). Exploring systematic SDG strategies is urgently needed to aid recovery from the pandemic and reinvigorate global SDG actions. Based on available data and comprehensive analysis of the literature, this paper highlights ongoing challenges facing the SDGs, identifies the effects of COVID-19 on SDG progress, and proposes a systematic framework for promoting the achievement of SDGs in the post-pandemic era. Progress towards attaining the SDGs was already lagging behind even before the onset of the COVID-19 pandemic. Inequitable distribution of food-energy-water resources and environmental crises clearly threaten SDG implementation. Evidently, there are gaps between the vision for SDG realization and actual capacity that constrain national efforts. The turbulent geopolitical environment, spatial inequities, and trade-offs limit the effectiveness of SDG implementation. The global public health crisis and socio-economic downturn under COVID-19 have further impeded progress toward attaining the SDGs. Not only has the pandemic delayed SDG advancement in general, but it has also amplified spatial imbalances in achieving progress, undermined connectivity, and accentuated anti-globalization sentiment under lockdowns and geopolitical conflicts. Nevertheless, positive developments in technology and improvement in environmental conditions have also occurred. In reflecting on the overall situation globally, it is recommended that post-pandemic SDG actions adopt a "Classification-Coordination-Collaboration" framework. Classification facilitates both identification of the current development status and the urgency of SDG achievement aligned with national conditions. Coordination promotes domestic/international and inter-departmental synergy for short-term recovery as well as long-term development. Cooperation is key to strengthening economic exchanges, promoting technological innovation, and building a global culture of sustainable development that is essential if the endeavor of achieving the SDGs is to be successful. Systematic actions are urgently needed to get the SDG process back on track.

LCA and negative emission potential of retrofitted cement plants under oxyfuel conditions at high biogenic fuel shares.

The implementation of oxyfuel carbon capture and storage technologies in combination with use of alternative fuels comprising high biogenic shares is promoted as an attractive climate change mitigation option for the cement sector to achieve low or even negative carbon emissions. Here, we perform a prospective life cycle assessment of two state-of-the art cement plants, one in Sweden and one in Germany, under conventional and retrofitted oxyfuel conditions considering alternative fuel mixes with increasing bio-based fractions of forest residues or dedicated bioenergy crops. The analysis also considers effects of the projected changes in the electricity systems up to 2050. Retrofitting the cement plants to oxyfuel reduces climate change impacts between 74 and 91%, while with additional use of biomass as alternative fuel the cement plants reach negative emission between - 24 and - 169 gCO2eq. kgclinker-1, depending on operational condition, location, and biomass type. Additional emission reduction of - 10 (Sweden) and - 128 gCO2eq. kgclinker-1 (Germany) are expected from the decarbonization of the future electricity systems. Retrofitting the cement plants to oxyfuel conditions shows trade-offs with other environmental impacts (e.g., human toxicity, water and energy depletion), which are partially offset with projected changes in electricity systems. Our results illustrate the large climate change mitigation potential in the cement sector that can be achieved by the implementation of oxyfuel carbon capture and storage and biomass use as alternative fuel.

Sensitivity and future exposure of ecosystem services to climate change on the Tibetan Plateau of China.

CONTEXT: Climate change has imposed tremendous impacts on ecosystem services. Recent attempts to quantify such impacts mainly focused on a basin or larger scale, or used limited time periods that largely ignore observations of long-term trends at a fine resolution, thereby affecting the recognition of climate change's effect on ecosystem services. OBJECTIVES: This study conducts a detailed and spatially explicit recognition of climate change's effect on ecosystem services and provides an intuitive map for decision-making and climate change adaptation planning. METHODS: We used long-term time series of ecosystem service assessments and various future climate scenarios to quantify the sensitivity and future exposure of ecosystem services to climate change on the Tibetan Plateau. RESULTS: Carbon sequestration (CS) and habitat quality experience significant growth, while water retention did not show any trend. Sensitivity patterns of these ecosystem services vary largely. For CS, more than half of the pixels showed a positive sensitivity to climate change, even though the degree of sensitivity is not high. There is substantial spatial heterogeneity in the exposure of ecosystem services to future climate changes, and high levels of future climate change increase the intensity of exposure. CONCLUSIONS: This study illustrates the complex spatial association between ecosystem services and climatic drivers, and these findings can help optimize local response strategies in the context of global warming. For example, the existing protected areas have notable conservation gaps for disturbance of future climate change on ecosystem services, especially in the southeastern part of the study area. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10980-021-01320-9.

The role of crystallinity and particle morphology on the sorption of dibutyl phthalate on polyethylene microplastics: Implications for the behavior of phthalate plastic additives.

The sorption behavior of phthalate additives in plastic and microplastic litter is an important process controlling the exposure, net health risk and ecotoxicity of these co-occurring pollutants. Plastic crystallinity and particle morphology are hypothesized to be important variables for microplastics sorption behavior, but to date there have been few direct studies to explicitly test for the influence of these parameters. To address this, in this study we explored the sorption of dibutyl phthalate (DBP) as a probe molecule to diverse polyethylene microplastics including irregularly-shaped pure polyethylene microplastics (IPPM), black plastic film microplastics (BPFM), white plastic film microplastics (WPFM), and commercial microspheres (CM), which had crystallinities ranging from 17 to 99%. Sorption kinetics for all materials could be well represented with both a pseudo-first-order (R2 = 0.87-0.93) and pseudo-second-order model (R2 = 0.87-0.93). Further, sorption was highly linear in the concentration range of 0.5-10 mg L-1, with no greater performance from a linear sorption model (R2 = 0.96-0.99) than the non-linear Freundlich or Temkin sorption models. The partition coefficient (Kd) of DBP sorption onto IPPM, BPFM, WPFM and CMs were 1974.55 L kg-1, 1483.85 L kg-1, 1477.45 L kg-1 and 509.37 L kg-1, respectively, showing a significant decrease with increasing crystallinity (r2 = 0.98). The particle size of microplastics (27-1000 µm) is, however, an indecisive factor affecting their sorption behavior for DBP in this study. This study provides new insight that crystallinity plays a governing role on the sorption of phthalate from microplastic. This should be considered in future exposure studies and assessments of phthalates from plastics and microplastics.

Integrated process simulation for bioethanol production: Effects of varying lignocellulosic feedstocks on technical performance.

Variations in lignocellulosic feedstock composition can influence conversion performance of bioethanol production, but such effects are overlooked in several studies that rely on standard conversion factors. This study investigates the effects of seven lignocellulosic feedstocks (belonging to the categories energy crops, forest and agricultural residues) on mass, carbon, water and energy balances for biochemical bioethanol production, including a comparison of individual process step yields. We find that overall bioethanol yields vary considerably, ranging between 19.0 and 29.0%, 27.3 and 46.2%, and 19.0 and 31.0%, for energy and carbon efficiency, respectively. The highest yields are found for switchgrass, which has the largest carbohydrate content, and the lowest for forest residues (spruce). Feedstock composition also affects water and carbon balances. Overall, the type of biomass influences conversion performances, thereby calling for explicit representation of the effects of biomass types in technical, economic and environmental assessment studies of bioethanol production.

The impact of interventions in the global land and agri-food sectors on Nature's Contributions to People and the UN Sustainable Development Goals.

Interlocked challenges of climate change, biodiversity loss, and land degradation require transformative interventions in the land management and food production sectors to reduce carbon emissions, strengthen adaptive capacity, and increase food security. However, deciding which interventions to pursue and understanding their relative co-benefits with and trade-offs against different social and environmental goals have been difficult without comparisons across a range of possible actions. This study examined 40 different options, implemented through land management, value chains, or risk management, for their relative impacts across 18 Nature's Contributions to People (NCPs) and the 17 Sustainable Development Goals (SDGs). We find that a relatively small number of interventions show positive synergies with both SDGs and NCPs with no significant adverse trade-offs; these include improved cropland management, improved grazing land management, improved livestock management, agroforestry, integrated water management, increased soil organic carbon content, reduced soil erosion, salinization, and compaction, fire management, reduced landslides and hazards, reduced pollution, reduced post-harvest losses, improved energy use in food systems, and disaster risk management. Several interventions show potentially significant negative impacts on both SDGs and NCPs; these include bioenergy and bioenergy with carbon capture and storage, afforestation, and some risk sharing measures, like commercial crop insurance. Our results demonstrate that a better understanding of co-benefits and trade-offs of different policy approaches can help decision-makers choose the more effective, or at the very minimum, more benign interventions for implementation.

Predominant regional biophysical cooling from recent land cover changes in Europe.

Around 70 Mha of land cover changes (LCCs) occurred in Europe from 1992 to 2015. Despite LCCs being an important driver of regional climate variations, their temperature effects at a continental scale have not yet been assessed. Here, we integrate maps of historical LCCs with a regional climate model to investigate air temperature and humidity effects. We find an average temperature change of -0.12 ± 0.20 °C, with widespread cooling (up to -1.0 °C) in western and central Europe in summer and spring. At continental scale, the mean cooling is mainly correlated with agriculture abandonment (cropland-to-forest transitions), but a new approach based on ridge-regression decomposing the temperature change to the individual land transitions shows opposite responses to cropland losses and gains between western and eastern Europe. Effects of historical LCCs on European climate are non-negligible and region-specific, and ignoring land-climate biophysical interactions may lead to sub-optimal climate change mitigation and adaptation strategies.

Which practices co-deliver food security, climate change mitigation and adaptation, and combat land degradation and desertification?

There is a clear need for transformative change in the land management and food production sectors to address the global land challenges of climate change mitigation, climate change adaptation, combatting land degradation and desertification, and delivering food security (referred to hereafter as "land challenges"). We assess the potential for 40 practices to address these land challenges and find that: Nine options deliver medium to large benefits for all four land challenges. A further two options have no global estimates for adaptation, but have medium to large benefits for all other land challenges. Five options have large mitigation potential (>3 Gt CO2 eq/year) without adverse impacts on the other land challenges. Five options have moderate mitigation potential, with no adverse impacts on the other land challenges. Sixteen practices have large adaptation potential (>25 million people benefit), without adverse side effects on other land challenges. Most practices can be applied without competing for available land. However, seven options could result in competition for land. A large number of practices do not require dedicated land, including several land management options, all value chain options, and all risk management options. Four options could greatly increase competition for land if applied at a large scale, though the impact is scale and context specific, highlighting the need for safeguards to ensure that expansion of land for mitigation does not impact natural systems and food security. A number of practices, such as increased food productivity, dietary change and reduced food loss and waste, can reduce demand for land conversion, thereby potentially freeing-up land and creating opportunities for enhanced implementation of other practices, making them important components of portfolios of practices to address the combined land challenges.

Contribution of forest wood products to negative emissions: historical comparative analysis from 1960 to 2015 in Norway, Sweden and Finland.

BACKGROUND: Forests and forest products can significantly contribute to climate change mitigation by stabilizing and even potentially decreasing the concentration of carbon dioxide (CO2) in the atmosphere. Harvested wood products (HWP) represent a common widespread and cost-efficient opportunity for negative emissions. After harvest, a significant fraction of the wood remains stored in HWPs for a period that can vary from some months to many decades, whereas atmospheric carbon (C) is immediately sequestered by vegetation re-growth. This temporal mismatch between oxidation of HWPs and C uptake by vegetation generates a net sink that lasts over time. The role of temporary carbon storage in forest products has been analysed and debated in the scientific literature, but detailed bottom-up studies mapping the fate of harvested materials and quantifying the associated emission profiles at national scales are rare. In this work, we quantify the net CO2 emissions and the temporary carbon storage in forest products in Norway, Sweden and Finland for the period 1960-2015, and investigate their correlation. We use a Chi square probability distribution to model the oxidation rate of C over time in HWPs, taking into consideration specific half-lives of each category of products. We model the forest regrowth and estimate the time-distributed C removal. We also integrate the specific HWP flows with an emission inventory database to quantify the associated life-cycle emissions of fossil CO2, CH4 and N2O. RESULTS: We find that assuming an instantaneous oxidation of HWPs would overestimate emissions of about 1.18 billion t CO2 (cumulative values for the three countries over the period 1960-2015).We also find that about 40 years after 1960, the starting year of our analysis, are sufficient to detect signs of negative emissions. The total amount of net CO2 emissions achieved in 2015 are about - 3.8 million t CO2, - 27.9 t CO2 and - 43.6 t CO2 in Norway, Sweden, and Finland, respectively. CONCLUSION: We argue for a more explicit accounting of the actual emission rates from HWPs in carbon balance studies and climate impact analysis of forestry systems and products, and a more transparent inclusion of the potential of HWP as negative emissions in perspective studies and scenarios. Simply assuming that all harvested carbon is instantaneously oxidized can lead to large biases and ultimately overlook the benefits of negative emissions of HWPs.

Cooling aerosols and changes in albedo counteract warming from CO2 and black carbon from forest bioenergy in Norway.

Climate impacts of forest bioenergy result from a multitude of warming and cooling effects and vary by location and technology. While past bioenergy studies have analysed a limited number of climate-altering pollutants and activities, no studies have jointly addressed supply chain greenhouse gas emissions, biogenic CO2 fluxes, aerosols and albedo changes at high spatial and process detail. Here, we present a national-level climate impact analysis of stationary bioenergy systems in Norway based on wood-burning stoves and wood biomass-based district heating. We find that cooling aerosols and albedo offset 60-70% of total warming, leaving a net warming of 340 or 69 kg CO2e MWh-1 for stoves or district heating, respectively. Large variations are observed over locations for albedo, and over technology alternatives for aerosols. By demonstrating both notable magnitudes and complexities of different climate warming and cooling effects of forest bioenergy in Norway, our study emphasizes the need to consider multiple forcing agents in climate impact analysis of forest bioenergy.

Choice of mineral fertilizer substitution principle strongly influences LCA environmental benefits of nutrient cycling in the agri-food system.

Increased nutrient cycling in the agri-food system is a way to achieve a healthier nutrient stewardship and more sustainable food production. In life cycle assessment (LCA) studies, use of recycled fertilizer products is often credited by the substitution method, which subtracts the environmental burdens associated with avoided production of mineral fertilizer from the system under study. The environmental benefits from avoided fertilizer production can make an important contribution to the results, but different calculation principles and often implicit assumptions are used to estimate the amount of avoided mineral fertilizer. This may hinder comparisons between studies. The present study therefore examines how the choice of substitution principles influences LCA results. Three different substitution principles, called one-to-one, maintenance, and adjusted maintenance, are identified, and we test the importance of these in a case study on cattle slurry management. We show that the inventory of avoided mineral fertilizer varies greatly when the different principles are applied, with strong influences on two-thirds of LCA impact categories. With the one-to-one principle, there is a risk of systematically over-estimating the environmental benefits from nutrient cycling. In a sensitivity analysis we show that the difference between the principles is closely related to the application rate and levels of residual nutrients in the soil. We recommend that LCA practitioners first and foremost state and justify the substitution method they use, in order to increase transparency and comparability with other studies.

Life-cycle assessment of a biogas power plant with application of different climate metrics and inclusion of near-term climate forcers.

This study assesses the environmental sustainability of electricity production through anaerobic co-digestion of sewage sludge and organic wastes. The analysis relies on primary data from a biogas plant, supplemented with data from the literature. The climate impact assessment includes emissions of near-term climate forcers (NTCFs) like ozone precursors and aerosols, which are frequently overlooked in Life Cycle Assessment (LCA), and the application of a suite of different emission metrics, based on either the Global Warming Potential (GWP) or the Global Temperature change Potential (GTP) with a time horizon (TH) of 20 or 100 years. The environmental performances of the biogas system are benchmarked against a conventional fossil fuel system. We also investigate the sensitivity of the system to critical parameters and provide five different scenarios in a sensitivity analysis. Hotspots are the management of the digestate (mainly due to the open storage) and methane (CH4) losses during the anaerobic co-digestion. Results are sensitive to the type of climate metric used. The impacts range from 52 up to 116 g CO2-eq./MJ electricity when using GTP100 and GWP20, respectively. This difference is mostly due to the varying contribution from CH4 emissions. The influence of NTCFs is about 6% for GWP100 (worst case), and grows up to 31% for GWP20 (best case). The biogas system has a lower performance than the fossil reference system for the acidification and particulate matter formation potentials. We argue for an active consideration of NTCFs in LCA and a critical reflection over the climate metrics to be used, as these aspects can significantly affect the final outcomes.

Life-cycle assessment of a Waste-to-Energy plant in central Norway: Current situation and effects of changes in waste fraction composition.

Waste-to-Energy (WtE) plants constitute one of the most common waste management options to deal with municipal solid waste. WtE plants have the dual objective to reduce the amount of waste sent to landfills and simultaneously to produce useful energy (heat and/or power). Energy from WtE is gaining steadily increasing importance in the energy mix of several countries. Norway is no exception, as energy recovered from waste currently represents the main energy source of the Norwegian district heating system. Life-cycle assessments (LCA) of WtE systems in a Norwegian context are quasi-nonexistent, and this study assesses the environmental performance of a WtE plant located in central Norway by combining detailed LCA methodology with primary data from plant operations. Mass transfer coefficients and leaching coefficients are used to trace emissions over the various life-cycle stages from waste logistics to final disposal of the ashes. We consider different fractions of input waste (current waste mix, insertion of 10% car fluff, 5% clinical waste and 10% and 50% wood waste), and find a total contribution to Climate Change Impact Potential ranging from 265 to 637gCO2eq/kg of waste and 25 to 61gCO2eq/MJ of heat. The key drivers of the environmental performances of the WtE system being assessed are the carbon biogenic fraction and the lower heating value of the incoming waste, the direct emissions at the WtE plant, the leaching of the heavy metals at the landfill sites and to a lesser extent the use of consumables. We benchmark the environmental performances of our WtE systems against those of fossil energy systems, and we find better performance for the majority of environmental impact categories, including Climate Change Impact Potential, although some trade-offs exist (e.g. higher impacts on Human Toxicity Potential than natural gas, but lower than coal). Also, the insertion of challenging new waste fractions is demonstrated to be an option both to cope with the excess capacity of the Norwegian WtE sector and to reach Norway's ambitious political goals for environmentally friendly energy systems.

Global spatially explicit CO2 emission metrics for forest bioenergy.

Emission metrics aggregate climate impacts of greenhouse gases to common units such as CO2-equivalents (CO2-eq.). Examples include the global warming potential (GWP), the global temperature change potential (GTP) and the absolute sustained emission temperature (aSET). Despite the importance of biomass as a primary energy supplier in existing and future scenarios, emission metrics for CO2 from forest bioenergy are only available on a case-specific basis. Here, we produce global spatially explicit emission metrics for CO2 emissions from forest bioenergy and illustrate their applications to global emissions in 2015 and until 2100 under the RCP8.5 scenario. We obtain global average values of 0.49 ± 0.03 kgCO2-eq. kgCO2(-1) (mean ± standard deviation) for GWP, 0.05 ± 0.05 kgCO2-eq. kgCO2(-1) for GTP, and 2.14·10(-14) ± 0.11·10(-14) °C (kg yr(-1))(-1) for aSET. We explore metric dependencies on temperature, precipitation, biomass turnover times and extraction rates of forest residues. We find relatively high emission metrics with low precipitation, long rotation times and low residue extraction rates. Our results provide a basis for assessing CO2 emissions from forest bioenergy under different indicators and across various spatial and temporal scales.