CO2 Balance Research Articles

Permafrost impacts on chemical weathering and CO2 budgets in the Tibetan Plateau: Micro-watershed perspective on a headwater catchment

Understanding the balance between alkalinity generation from carbonate and silicate weathering, and the effect of sulfide weathering, is crucial for comprehending the impact of these processes on atmospheric CO2 levels. However, the sequestration potential and the net balance of CO2 between the release from sulfide weathering and the consumption by silicate weathering in permafrost environments remain contentious. This study examines the Shaliu River, a typical permafrost-dominated headwater catchment in the Northeast Tibetan Plateau, from a micro-watershed perspective to elucidate the effects of permafrost on chemical weathering and CO2 budgets during ablation period. Silicate weathering in the Shaliu River contributes 25–32 % to solute load, while carbonate weathering contributes 39–45 %. Sulfuric acid (H2SO4) plays a key role in carbonate weathering, accounting for 74 % of it and 37 % of the river’s solute load, especially in the permafrost-covered upstream areas. In contrast, bicarbonate (HCO3–) impacts are more evident in the lower reaches without permafrost. By integrating silicate and carbonate weathering with H2SO4-driven reactions, CO2 budget analysis indicates that the Shaliu River basin acts as a carbon source. The MEANDIR inversion model consistently depicts the watershed as a carbon source, influenced by permafrost and lithology. This implies that sulfide oxidation to produce sulfuric acid (H2SO4) drives carbonate weathering may significantly counterbalance the carbon sequestration associated with silicate weathering over geological timescales. The study provides a comprehensive understanding of the carbon budget dynamics within the permafrost-dominated watersheds of the Tibetan Plateau, enhancing the comprehension of carbon cycle processes in high-altitude ecosystems.

Interannual and seasonal variability of the air–sea CO2 exchange at Utö in the coastal region of the Baltic Sea

Abstract. Oceans alleviate the accumulation of atmospheric CO2 by absorbing approximately a quarter of all anthropogenic emissions. In the deep oceans, carbon uptake is dominated by aquatic phase chemistry, whereas in biologically active coastal seas the marine ecosystem and biogeochemistry play an important role in the carbon uptake. Coastal seas are hotspots of organic and inorganic matter transport between the land and the oceans, and thus they are important for the marine carbon cycling. In this study, we investigate the net air–sea CO2 exchange at the Utö Atmospheric and Marine Research Station, located at the southern edge of the Archipelago Sea within the Baltic Sea, using the data collected during 2017–2021. The air–sea fluxes of CO2 were measured using the eddy covariance technique, supported by the flux parameterization based on the pCO2 and wind speed measurements. During the spring–summer months (April–August), the sea was gaining carbon dioxide from the atmosphere, with the highest monthly sink fluxes typically occurring in May, being −0.26 µmol m−2 s−1 on average. The sea was releasing the CO2 to the atmosphere in September–March, and the highest source fluxes were typically observed in September, being 0.42 µmol m−2 s−1 on average. On an annual basis, the study region was found to be a net source of atmospheric CO2, and on average, the annual net exchange was 27.1 gC m−1 yr−1, which is comparable to the exchange observed in the Gulf of Bothnia, the Baltic Sea. The annual net air–sea CO2 exchanges varied between 18.2 (2018) and 39.1 gC m−1 yr−1 (2017). During the coldest year, 2017, the spring–summer sink fluxes remained low compared to the other years, as a result of relatively high seawater pCO2 in summer, which never fell below 220 µatm during that year. The spring–summer phytoplankton blooms of 2017 were weak, possibly due to the cloudy summer and deeply mixed surface layer, which restrained the photosynthetic fixation of dissolved inorganic carbon in the surface waters. The algal blooms in spring–summer 2018 and the consequent pCO2 drawdown were strong, fueled by high pre-spring nutrient concentrations. The systematic positive annual CO2 balances suggest that our coastal study site is affected by carbon flows originating from elsewhere, possibly as organic carbon, which is remineralized and released to the atmosphere as CO2. This coastal source of CO2 fueled by the organic matter originating probably from land ecosystems stresses the importance of understanding the carbon cycling in the land–sea continuum.

Potential nutrient, carbon and fisheries impacts of large-scale seaweed and shellfish aquaculture in Europe evaluated using operational oceanographic model outputs

Large-scale seaweed and shellfish aquaculture are increasingly being considered by policymakers as a source of food, animal feed and bioproducts for Europe. These aquacultures are generally thought to be low impact or even beneficial for marine ecosystems as they are ‘extractive’ – i.e., growing passively on foodstuff already available in seawater, and with potential habitat provision, fisheries, climate mitigation and eutrophication mitigation benefits. At some scale however, over-extraction of nutrients or chlorophyll could potentially have a negative effect on natural systems. Understanding the likely impacts of aquaculture production at scale is important to identify when safe limits are being approached. Taking seaweed aquaculture as the primary focus, this work uses operational oceanographic model outputs to drive prognostic growth models to predict the likely optimal distribution of seaweed farms across European waters to meet different production scenarios. A novel nutrient transport scheme is then used to model the interacting ‘footprints’ of nutrient drawdown from aquaculture facilities to demonstrate the likely spatial impact of large-scale aquaculture. Evaluation of both seaweed and shellfish contributions to CO2 balance under large scale production, and the potential impact on fisheries are also considered. The study finds that the impact of intensive seaweed aquaculture on nutrient availability could be significant where many farms are placed close together; but at the regional/basin scale even the highest level of production considered does not significantly impact total nutrient budgets. Seaweed aquaculture has the potential to extract large amounts of carbon dioxide, but the impact on carbon budgets depends on the end-use of the extracted seaweed. Shellfish aquaculture is a net source of CO2 due to the impact of calcification of shells on the carbonate system (i.e., alkalinity removal). However, gram-for-gram the CO2 impact of shellfish production is likely to be less than the impact of land-based meat production. Whilst operational oceanographic models are useful for taking a ‘broad brush’ approach to likely placement and impacts of aquaculture, reliable yield predictions for individual locations across European waters would require models integrating more physical and biogeochemical factors (wave environment, local currents, riverine inputs) at a finer scale than currently achievable.

Decadal increases in carbon uptake offset by respiratory losses across northern permafrost ecosystems

Tundra and boreal ecosystems encompass the northern circumpolar permafrost region and are experiencing rapid environmental change with important implications for the global carbon (C) budget. We analysed multi-decadal time series containing 302 annual estimates of carbon dioxide (CO2) flux across 70 permafrost and non-permafrost ecosystems, and 672 estimates of summer CO2 flux across 181 ecosystems. We find an increase in the annual CO2 sink across non-permafrost ecosystems but not permafrost ecosystems, despite similar increases in summer uptake. Thus, recent non-growing-season CO2 losses have substantially impacted the CO2 balance of permafrost ecosystems. Furthermore, analysis of interannual variability reveals warmer summers amplify the C cycle (increase productivity and respiration) at putatively nitrogen-limited sites and at sites less reliant on summer precipitation for water use. Our findings suggest that water and nutrient availability will be important predictors of the C-cycle response of these ecosystems to future warming.

Projection of the Airborne CO2 Concentration by Land/Ocean Absorption Dynamics and Fossil-Fuel Reserve Depletion

The paper has been suggested by the following observations: (1) the atmospheric growth rate of carbon dioxide concentration is smaller than that ascribed to the emission of fossil-fuel combustion and (2) the fossil-fuel reserves are finite. The first observation leads to a simple dynamic model, based on the balance of CO2 land/ocean absorption and anthropogenic emissions, only limited by the depletion of fossil-fuel reserves, in a business-as-usual scenario. The second observation suggests of projecting the past CO2 emissions to the future, by constraining emissions to the limit of reserve availability. Similar projections are available in the literature, but either driven by heuristics or by complex simulation packages. The paper provides a simple and formal method only driven by historical data, their uncertainty and simple models. The method aims to provide CO2 concentration projections, which being constrained by fossil-fuel finite reserve may be in principle employed as bounds to forecasting exercises. The time–invariant dynamics of the land/ocean absorption is the simplification of a more complex set of equations describing carbon dioxide exchange between different reservoirs. Contribution of other greenhouse gases like methane and nitrous oxide has been neglected, since their emissions cannot be projected with the paper methodology. Comparison with recent profiles of the Intergovernmental Panel on Climate Change (IPCC) confirms that the finite-reserve projections of the fossil fuel emissions is close to those of a moderate Shared Socioeconomic Scenario (SSP) like SSP2-4.5—a result in agreement with other authors—but also reveals the limits of the simplified model, when extending the tuned dynamics of the recent mean CO2 exchanges to long-term future. The limits derive from linearity, time invariance, and aggregation assumptions, which allow a more complex model of CO2 exchanges to be simplified and tuned on experimental data.

CO2 emissions from solid biofuel consumption in rural communities in Durango, Mexico

Objective: the objective of this study was to calculate the amount, in kilotons per year (kt a-1), of CO2 emissions from firewood consumption in rural communities of Durango in managed areas (UMAFOR– Forest Management Units) and at the municipality scale. Design/ Methodology/ Approach: the firewood consumption was determined for each of the UMAFOR areas and the 39 municipalities into which the state of Durango is divided. Greenhouse Inventory Software® was used to determine CO2 emissions. Results: the annual CO2 balance due to firewood consumption in Durango was 268.05 kt of CO2. These emissions in relation to the national scale represent 1.52% per year. Those UMAFOR and the municipalities that are geographically located in the semi-arid zone of the state of Durango were those with the higher CO2 emissions. Findings/ Conclusions: it is necessary to couple the consumption of firewood with eco-technologies that favor its efficient consumption, thus mitigating CO2 emissions.

Revolutionizing heat distribution: A method for harnessing industrial waste heat with supra-regional district heating networks

In both practice and literature, there is a lack of a concept for a supra-regional district heating network that efficiently transports heat from renewable and industrial waste heat sources to multiple heat sinks and regional district heating networks, like the high-voltage electricity transmission network in the electricity sector. This paper addresses this gap by presenting a novel method for the basic design of a supra-regional district heating network and its evaluation, along with key performance indicators for assessment. The method highlights essential data requirements and the derivation process necessary to enable the integration of such a heating network. Additionally, it describes how a basic design of such a network can be made feasible and evaluated. This method is then applied to a case study to demonstrate its implementation for a real-world application. Furthermore, this case study aims to either demonstrate or provisionally disprove the general feasibility of a supra-regional district heating network. The results indicate that the implementation of such a network has a positive impact on the CO2 balance and primary energy demand. The case study further demonstrates the technical feasibility of such a network, showing that a high linear heat density can be achieved through integration and that temperature levels within the network can be maintained adequately. This study confirmed that the developed method can effectively assess whether further investigations into implementing a supra-regional district heating network in a specific region are warranted. Additionally, the method offers a guideline on how to initially design such a network.

A step closer to sustainable CO2 conversion: Limonene carbonate production driven by ionic liquids

This work aims to advance the biocarbonate concept by developing the first process to produce limonene carbonate based on ionic liquids (ILs). Conventional petroleum-derived cyclic carbonates are recognized products partially composed of CO2 with the main drawback of the high energy consumption that imposes epoxide production. In contrast, natural epoxidable compounds, such as terpenes, stand out in the literature as a more sustainable open research line to enable CO2 conversion processes with better sustainable indicators. Limonene, an abundant natural compound, is identified as a key terpene in the aforementioned discussion. Ammonium-based ILs are experimentally selected and optimized, after covering massive anion and cation substituent tuning, achieving high selectivity and competitive yields to limonene carbonate. The reaction-extraction platform concept, which recovers the catalyst by liquid-liquid extraction, is envisioned and developed using a rational experimental-computational approach. The work concludes with a novel process to effectively produce limonene carbonate by using an IL catalyst and water as an extracting solvent. Ultimately, taking advance of the process simulation, a CO2 emissions assessment was conducted. Using renewable raw materials enhances the sustainability of CO2 conversion to cyclic carbonate, reducing global warming impact compared to fossil-based epoxides. However, limonene extraction and epoxidation have a tangible impact on the overall result of CO2 balance, turning efforts outside battery limits of the CO2 conversion process in the search of a limonene carbonate production line with negative neat CO2 emissions that may change the paradigm in the fixation of CO2 through cycloaddition reactions.

Impact of vegetation composition and seasonality on sensitivity of modelled CO2 exchange in temperate raised bogs

Encroachment of vascular plants (VP) in temperate raised bogs, as a consequence of altered hydrological conditions and nutrient input, is widely observed. Effects of such vegetation shift on water and carbon cycles are, however, largely unknown and identification of responsible plant physiological traits is challenging. Process-based modelling offers the opportunity of gaining insights into ecosystem functioning beyond observations, and to infer decisive trait shifts of plant functional groups. We adapted the Soil–Vegetation–Atmosphere Transfer model pyAPES to a temperate raised bog site by calibration against measured peat temperature, water table and surface CO2 fluxes. We identified the most important traits determining CO2 fluxes by conducting Morris sensitivity analysis (MSA) under changing conditions throughout the year and simulated VP encroachment. We further investigated transferability of results to other sites by extending MSA to parameter ranges derived from literature review. We found highly variable intra-annual plant traits importance determining ecosystem CO2 fluxes, but only a partial shift of importance of photosynthetic processes from moss to VP during encroachment. Ecosystem respiration was dominated by peat respiration. Overall, carboxylation rate, base respiration rate and temperature sensitivity (Q10) were most important for determining bog CO2 balance and parameter ranking was robust even under the extended MSA.

Life Cycle Assessment of Wheat Straw Pyrolysis with Volatile Fractions Chemical Looping Combustion

Among the approaches to facilitating negative CO2 emissions is biochar production. Biochar is generated in the pyrolysis of certain biomasses. In the pyrolysis process, carbon in the biomass is turned into a solid, porous, carbon-rich, and stable material that can be captured from the soil after a period of from a few decades to several centuries. In addition to this long-term carbon sequestration role, biochar is also beneficial for soil performance as it helps to restore soil fertility and improves the retention and diffusion of water and nutrients. This work presents a Life Cycle Assessment of different pyrolysis approaches for biochar production. Biomass pyrolysis is performed in a fixed-bed reactor, which operates at a mild temperature (550 °C). Biochar is obtained as solid product of the pyrolysis, but there are also liquid (bio-oil) and gaseous products (syngas). The pyrolysis gas is partly used to fulfil the energy demand of the pyrolysis process, which is highly endothermic. In the conventional approach, CO2 is produced during the combustion of syngas and emitted to the atmosphere. Another approach to facilitate CO2 capture and thus obtain more negative CO2 emissions in the pyrolysis process is burning syngas and bio-oil in a Chemical Looping Combustion unit. Life Cycle Assessment was performed of these approaches toward biomass pyrolysis to evaluate their environmental impact. The Chemical Looping Combustion approach significantly reduced the values of 7 of the 16 environmental impact indicators studied, along with the Global Warming Potential among them, it slightly increased the value of one indicator related to the use of fossil resources, and it maintained the values of the remaining 8 indicators. Environmental impact reduction occurs due to the avoidance of CO2 and NOx emissions with Chemical Looping Combustion. The CO2 balances of the different pyrolysis approaches with Chemical Looping Combustion configurations were compared with a base case, which constituted the direct combustion of wheat straw to obtain thermal energy. Direct biomass combustion for the production of 17.1 MJ of thermal energy had CO2 positive emissions of 0.165 kg. If the gaseous fraction was burned by Chemical Looping Combustion, CO2 was captured and the emissions became increasingly negative, until a value of −3.30 kg/17.1 MJ was generated. If bio-oil was also burned by this technology, the negative trend of CO2 emissions continued, until they reached a value of −3.66 kg.

Integrated evaluation of city-level CO2 emissions and sinks from 2010 to 2019: Spatio-temporal patterns in the Yangtze River Economic Belt of China

The intensifying impact of global climate change has led to increased attention being paid to carbon dioxide (CO2) emissions and sinks. However, it remains a challenge to accurately assess and map the spatial distribution of CO2 emissions and sinks. Previous studies have primarily focused on national and provincial level research, leaving city-level studies relatively overlooked. Acknowledging the significance of interregional differences and the crucial ecological and economic aspects of the Yangtze River Economic Belt (YREB), we devised a research framework to analyse spatio-temporal patterns through city-level CO2 emissions and sinks. The city-level CO2 emissions were estimated using provincial data and linear allocation models, while CO2 sinks were estimated based on the areas of ecosystems and their corresponding sink coefficients. The analysis of YERB's spatio-temporal patterns focuses on regional hotspots, outliers, and time-series clustering. The findings show that: (1) Between 2010 and 2019, ecosystems within YREB absorbed approximately 41.17%–46.70% of CO2 emissions, with the increase rate of CO2 emissions being lower than that of sinks. (2) City-level CO2 in Western Region of YREB exhibited low emissions and high sinks, while Eastern Region showed high emissions and low sinks, and these characteristics were intensifying. (3) City-level CO2 emissions and sinks demonstrated a “core-periphery” clustering pattern. (4) The regional CO2 balance was predominantly driven by most cities in Eastern Region. This study provides a comprehensive understanding of CO2 emissions and sinks at the city level and offers valuable insights for developing regional collaborative emission reduction strategies in YREB.

Empowering Students to Create Climate-Friendly Schools

In Germany, there are over 32,000 schools, representing great potential for climate protection. On the one hand, this applies to educational work, as understanding the effects of climate change and measures to reduce GHG emissions is an important step to empower students with knowledge and skills. On the other hand, school buildings are often in bad condition, energy is wasted, and the possibilities for using renewable energies are hardly used. In our “Schools4Future” project, we enabled students and teachers to draw up their own CO2 balances, identify weaknesses in the building, detect wasted electricity, and determine the potential for using renewable energies. Emissions from the school cafeteria, school trips, and paper consumption could also be identified. The fact that the data can be collected by the students themselves provides increased awareness of the contribution made to the climate balance by the various school areas. The most climate-friendly school emits 297 kg whilst the school with the highest emissions emits over one ton CO2 per student and year. Our approach is suitable to qualify students in the sense of citizen science, carry out a scientific investigation, experience self-efficacy through one’s own actions, and engage politically regarding their concerns.

Bi-objective model for tactical planning in corn supply chain considering CO2 balance

This paper addresses the Brazilian corn production logistic supply chain with an optimisation model considering carbon emission from transportation and carbon sequestration from corn production. The focus is on the higher-level decision planning, which includes the best regions for corn cultivation, location and sizing of silos to store grains, transportation modes with intermodality, considering several resource constraints to meet the demands of domestic market and export. Two conflicting objectives are considered: the logistics costs of the supply chain and the balance of CO 2 . Accurate data are used to evaluate the model and the Pareto optimal solutions are produced in scenarios potentially feasible in practice. The solutions showed relevant information to guide decisions about investment in logistic infrastructure. We demonstrated that cleaner transportation routes lead to solutions that have larger carbon stocks with 3–5% increase in costs by only choosing more suitable regions for corn cultivation and transportation modes.

Large variation in carbon dioxide emissions from tropical peat swamp forests due to disturbances

The huge carbon stock of tropical peat swamp forest (PSF) in Southeast Asia has been threatened by environmental disturbances due to quasi-periodic El Niño-Southern Oscillation (ENSO) droughts, biomass and peat burning, smoke haze, drainage, and deforestation. Carbon dioxide (CO2) emissions from such disturbances have not been well quantified because of insufficient field data. Therefore, we quantified the ecosystem-scale CO2 balance and examine the disturbance effects from a long-term field experiment for 12–15 years at three PSF sites with different degrees of degradation in Indonesia. Here, we show a drastic change of an undrained PSF from a CO2 sink to a source owing to the transient groundwater lowering by the droughts, a significant decrease in ecosystem photosynthesis due to the radiation attenuation by smoke haze in drought years, and long-lasting CO2 emissions through enhanced peat decomposition by drainage. The impact on CO2 emissions was greater from drainage than drought-induced disturbances.

Breathing Planet Earth: Analysis of Keeling’s Data on CO2 and O2 with Respiratory Quotient (RQ), Part II: Energy-Based Global RQ and CO2 Budget

For breathing humans, the respiratory quotient (RQ = CO2 moles released/O2 mols consumed) ranges from 0.7 to 1.0. In Part I, the literature on the RQ was reviewed and Keeling’s data on atmospheric CO2 and O2 concentrations (1991–2018) were used in the estimation of the global RQ as 0.47. A new interpretation of RQGlob is provided in Part II by treating the planet as a “Hypothetical Biological system (HBS)”. The CO2 and O2 balance equations are adopted for estimating (i) energy-based RQGlob(En) and (ii) the CO2 distribution in GT/year and % of CO2 captured by the atmosphere, land, and ocean. The key findings are as follows: (i) The RQGlob(En) is estimated as 0.35 and is relatively constant from 1991 to 2020. The use of RQGlob(En) enables the estimation of CO2 added to the atmosphere from the knowledge of annual fossil fuel (FF) energy data; (ii) The RQ method for the CO2 budget is validated by comparing the annual CO2 distribution results with results from more detailed models; (iii) Explicit relations are presented for CO2 sink in the atmosphere, land, and ocean biomasses, and storage in ocean water from the knowledge of curve fit constants of Keeling’s curves and the RQ of FF and biomasses; (iv) The rate of global average temperature rise (0.27 °C/decade) is predicted using RQGlob,(En) and the annual energy release rate and compared with the literature data; and (v) Earth’s mass loss in GT and O2 in the atmosphere are predicted by extrapolating the curve fit to the year 3700. The effect of RQGlob and RQFF on the econometry and policy issues is briefly discussed.

The Net GHG Balance and Budget of the Permafrost Region (2000–2020) From Ecosystem Flux Upscaling

AbstractThe northern permafrost region has been projected to shift from a net sink to a net source of carbon under global warming. However, estimates of the contemporary net greenhouse gas (GHG) balance and budgets of the permafrost region remain highly uncertain. Here, we construct the first comprehensive bottom‐up budgets of CO2, CH4, and N2O across the terrestrial permafrost region using databases of more than 1000 in situ flux measurements and a land cover‐based ecosystem flux upscaling approach for the period 2000–2020. Estimates indicate that the permafrost region emitted a mean annual flux of 12 (−606, 661) Tg CO2–C yr−1, 38 (22, 53) Tg CH4–C yr−1, and 0.67 (0.07, 1.3) Tg N2O–N yr−1 to the atmosphere throughout the period. Thus, the region was a net source of CH4 and N2O, while the CO2 balance was near neutral within its large uncertainties. Undisturbed terrestrial ecosystems had a CO2 sink of −340 (−836, 156) Tg CO2–C yr−1. Vertical emissions from fire disturbances and inland waters largely offset the sink in vegetated ecosystems. When including lateral fluxes for a complete GHG budget, the permafrost region was a net source of C and N, releasing 144 (−506, 826) Tg C yr−1 and 3 (2, 5) Tg N yr−1. Large uncertainty ranges in these estimates point to a need for further expansion of monitoring networks, continued data synthesis efforts, and better integration of field observations, remote sensing data, and ecosystem models to constrain the contemporary net GHG budgets of the permafrost region and track their future trajectory.

Assessing belowground carbon storage after converting a temperate permanent grassland into a bamboo (Phyllostachys) plantation

AbstractBamboo (Phyllostachys sp.) is considered a sustainable resource that can replace fossil fuel‐based products. Its additional ability to sequester organic carbon in the soil (SOC) makes it a promising nature‐based solution for combating climate change. However, bamboo's soil C storage potential may vary considerably between species or growing conditions and needs to be better quantified, especially in temperate climates where data are lacking. In the present research, the SOC dynamics of plots converted from grassland to plantations of three bamboo species (i.e. Phyllostachys nigra, Phyllostachys aurea and Phyllostachys aureosulcata), planted 12 years ago on podzol (World Reference Base classification) in the Belgian Campine region, have been studied. Soil and root samples were taken until a depth of 40 cm using a 10 cm interval. Besides, the total belowground C stability (mgCO2‐C g−1 C h−1) was assessed by measuring during 3 months the carbon dioxide (CO2) efflux relative to the belowground C stock. Based on an equivalent soil mass, only P. aureosulcata, the species with the highest culm basal area, had a significant (p < .001) SOC increase of 5.0 kg C m−2 (relative increase of +94%) as compared with grassland. Considering the sum of C stocks in the soil, roots and leaf litter, all bamboo species showed significant (p < .001) C storage, i.e. +3.6 kg C m−2 (+64%), +5.3 kg C m−2 (+94%) and +8.6 kg C m−2 (+151%) for P. nigra, P. aurea and P. aureosulcata, respectively. In addition, bamboo's relative basal CO2 efflux (0.007, 0.006 and 0.008 mgCO2‐C g−1 C h−1, respectively) was remarkably lower than in the grassland (0.012 mgCO2‐C g−1 C h−1), though it was only significant for P. aurea. This study highlights that converting temperate permanent grassland into Phyllostachys bamboo plantation can result in net and rapid organic C storage by increasing the total belowground C stability and C input. Further research regarding the net CO2 balance of bamboo‐derived products is still required to fully assess its climate change mitigation potential.

Estimation of cucumber net primary production using environmental and control information in a smart multi-span plastic greenhouse

A smart greenhouse can be considered as a very large chamber under closed conditions. The amount of change in CO2 concentration inside the greenhouse during periods without CO2 fertilization depends on the net primary production (i.e., net carbon assimilated by plants via photosynthesis) (NPP) of the crops grown in the greenhouse. In this study, we estimated the NPP of cucumbers in a small-scale smart multi-span plastic greenhouse using environmental and control information collected during a low-temperature period when the greenhouse was frequently closed. The timescale for robustly calculating NPP using the temporal change in the CO2 concentration inside the greenhouse was empirically determined (=10 min), and a random forest-based NPP model was established using the calculated NPP and internal and external environmental greenhouse data to estimate NPP, even in the cases of opening roof windows or supplying CO2. The estimated NPP showed previously known relationships with environmental variables in the greenhouse, and cumulative NPP was consistent with cucumber growth. Based on the CO2 balance equation of a smart greenhouse and estimated NPP, we quantified the amount of CO2 supplied and CO2 emissions via the roof windows. The CO2 budget estimation errors and suggestions for reducing errors were discussed. The quantified CO2 budget in the greenhouse, including NPP, can be used for evaluating economic feasibility and improving crop productivity.

Hydrologic and Landscape Controls on Rock Weathering Along a Glacial Gradient in South Central Alaska, USA

AbstractRock weathering impacts atmospheric CO2 levels with silicate rock dissolution removing CO2, and carbonate dissolution, pyrite oxidation, and organic rock carbon oxidation producing CO2. Glacierization impacts the hydrology and geomorphology of catchments and glacier retreat due to warming can increase runoff and initiate landscape succession. To investigate the impact of these changes on catchment scale weathering CO2 balances, we report monthly samples of solute chemistry and continuous discharge records for a sequence of glacierized watersheds draining into Kachemak Bay, Alaska. We partition solute and acid sources and estimate inorganic weathering CO2 balances using an inverse geochemical mixing model. Furthermore, we investigated how solutes vary with discharge conditions utilizing a concentration‐runoff framework. We develop an analogous fraction‐runoff framework which allows us to investigate changes in weathering contributions at different flows. Fraction‐runoff relationships suggest kinetic limitations on all reactions in glacierized catchments, and only silicate weathering in less glacierized catchments. Using forest cover as a proxy for landscape age and stability, multiple linear regression shows that faster reactions (pyrite oxidation) contribute less to the solute load with increasing forest cover, whereas silicate weathering (slow reaction kinetics) contributes more. Overall, in glacierized catchments, we find elevated weathering fluxes at high runoff despite significant dilution effects. This makes flux estimates that account for dilution more important in glacierized catchments. Our findings quantify how glaciers modify the inorganic weathering CO2 balance of catchments through hydrologic and geomorphic forcings, and support the previous hypothesis that deglaciation will be accompanied by a shift in inorganic weathering CO2 balances.

Calculating the Greenhouse Gas Emissions of the Central Depot of the Kunsthistorisches Museum, Vienna – First Results of the Pilot Study

ABSTRACT Museums are important actors in the fight against climate change. In order to limit global warming to a maximum of 1.5° Celsius, European museums are required to reduce their CO2 emissions to contribute to climate protection. The first step towards reducing the CO2 footprint of a building is to know about its current status. The acquisition and analysis of an organization’s emissions is performed by means of a CO2 balance; this evaluation identifies relevant action, indicates the saving potential, and enables a prioritization of procedures. In the museum sector, the carbon footprinting is a relatively new concept. The first initiatives in the German-speaking countries focus on the portions of museums used for exhibits. As part of her dissertation, the author started a pilot project with the KHM-Museumsverband (KHM Museum Association) in Austria to document CO2 emissions in the storage areas of the museum. The Competence Center for Climate Neutrality at the Center for Global Change and Sustainability at the BOKU – (Universität für Bodenkultur Wien, University of Natural Resources and Life Sciences Vienna) – offered valuable expertise to support this study. This article provides the first insights into the research project, which started in fall 2021 and presents preliminary results of the case study.