Atmospheric CO2 Emissions Research Articles

Climate Change, Government Agricultural Expenditure, and Agricultural Growth Nexus in Afghanistan: An Investigation with FMOLS and DOLS Approaches

Agriculture is one of the main providers to Afghanistan’s economy. Since 2002, the government, in collaboration with donor organizations and the private sector, has undertaken various projects in the agricultural industry. However, a notable upsurge in atmospheric CO2 emissions has resulted in significant climate change influences in contemporary decades. Therefore, this article examines the causal association between climate change, government agricultural expenditure, and agricultural growth in Afghanistan from 2002 to 2020. Despite evidence that climate change may be a primary driver of Afghanistan’s agricultural production decline, no specific studies have addressed this matter comprehensively. This article’s empirical investigation reveals a negative association between CO2 emissions and agricultural production, indicating that rising emissions are linked to decreased agricultural output, subsequently impacting Afghanistan’s agricultural growth. Both theoretical considerations and empirical findings highlight the importance of adopting clean and green energy solutions and technologies to mitigate pollution in Afghanistan. Furthermore, the research underscores that the impacts of carbon dioxide emissions on agriculture production exhibit robust long-term dynamics, contributing to the heterogeneity of the findings. Additionally, the study establishes a positive correlation between government agricultural expenditure and agricultural production. Consequently, it is strongly recommended that the Afghan government take proactive initiatives to enhance the agricultural sector. This can be accomplished by allocating more financial resources and implementing projects that promise long-term benefits for the country’s agricultural development.

Mixed Perovskite Phases of BaTiO3/BaTi5O11 for Efficient Electrochemical Reduction of CO2 to CO.

One of the most promising approaches in solving the energy crisis and reducing atmospheric CO2 emissions is artificial photosynthetic CO2 reduction. The electrochemical method for CO2 reduction is more appealing since it can be operated under ambient conditions, and the product selectivity strongly depends on the applied potential. Perovskites with ferroelectric properties strongly adsorb linear CO2 molecules. In this study, barium titanate (BaTiO3) perovskite is used as an electrocatalyst to promote CO2 activation and conversion to CO. Perovskite catalysts were prepared by ball-milling followed by annealing at 900 °C for 4 to 6 h in an open atmosphere. The TEM and SEM study shows that the particle size varies in the range of 80-200 nm. Mixed phases of BaTiO3 and BaTi5O11 supported on nitrogen-doped carbon nanotubes are found to be highly active for electrocatalytic CO2 reduction to CO with maximum Faradaic efficiency of 89.4 % at -1.0 V versus Ag/AgCl in CO2 saturated 0.5 KOH solution. This study concludes that mixed phases of BaTiO3 and BaTi5O11 are more active and highly selective for CO2 conversion to CO compared to single-phase BaTiO3.

A Modeling Framework of Atmospheric CO2 in the Mediterranean Marseille Coastal City Area, France

As atmospheric CO2 emissions and the trend of urbanization both increase, the ability to accurately assess the CO2 budget from urban environments becomes more important for effective CO2 mitigation efforts. This task can be difficult for complex areas such as the urban–coastal Mediterranean region near Marseille, France, which contains the second most populous city in France as well as a broad coastline and nearby mountainous terrain. In this study, we establish a CO2 modeling framework for this region for the first time using WRF-Chem and demonstrate its efficacy through comparisons against cavity-ringdown spectrometer measurements recorded at three sites: one 75 km north of the city in a forested area, one in the city center, and one at the urban/coastal border. A seasonal CO2 analysis compares Summertime 2016 and Wintertime 2017, to which Springtime 2017 is also added due to its noticeably larger vegetation uptake values compared to Summertime. We find that there is a large biogenic signal, even in and around Marseille itself, though this may be a consequence of having limited fine-scale information on vegetation parameterization in the region. We further find that simulations without the urban heat island module had total CO2 values 0.46 ppm closer to the measured enhancement value at the coastal Endoume site during the Summertime 2016 period than with the module turned on. This may indicate that the boundary layer on the coast is less sensitive to urban influences than it is to sea-breeze interactions, which is consistent with previous studies of the region. A back-trajectory analysis with the Lagrangian Particle Dispersion Model found 99.83% of emissions above 100 mol km−2 month−1 captured in Summer 2016 by the three measurement towers, providing evidence of the receptors’ ability to constrain the domain. Finally, a case study showcases the model’s ability to capture the rapid change in CO2 when transitioning between land-breeze and sea-breeze conditions as well as the recirculation of air from the industrial Fos region towards the Marseille metroplex. In total, the presented modeling framework should open the door to future CO2 investigations in the region, which can inform policymakers carrying out CO2 mitigation strategies.

A regression-based approach to the CO2 airborne fraction

The global fraction of anthropogenically emitted carbon dioxide (CO2) that stays in the atmosphere, the CO2 airborne fraction, has been fluctuating around a constant value over the period 1959 to 2022. The consensus estimate of the airborne fraction is around 44%. In this study, we show that the conventional estimator of the airborne fraction, based on a ratio of changes in atmospheric CO2 concentrations and CO2 emissions, suffers from a number of statistical deficiencies. We propose an alternative regression-based estimator of the airborne fraction that does not suffer from these deficiencies. Our empirical analysis leads to an estimate of the airborne fraction over 1959–2022 of 47.0% (± 1.1%; 1σ), implying a higher, and better constrained, estimate than the current consensus. Using climate model output, we show that a regression-based approach provides sensible estimates of the airborne fraction, also in future scenarios where emissions are at or near zero.

Unexpected sustained soil carbon flux in response to simultaneous warming and nitrogen enrichment compared with single factors alone.

Recent observations document that long-term soil warming in a temperate deciduous forest leads to significant soil carbon loss, whereas chronic soil nitrogen enrichment leads to significant soil carbon gain. Most global change experiments like these are single factor, investigating the impacts of one stressor in isolation of others. Because warming and ecosystem nitrogen enrichment are happening concurrently in many parts of the world, we designed a field experiment to test how these two factors, alone and in combination, impact soil carbon cycling. Here, we show that long-term continuous soil warming or nitrogen enrichment when applied alone followed the predicted response, with warming resulting in significant soil carbon loss and nitrogen fertilization tending towards soil carbon gain. The combination treatment showed an unanticipated response, whereby soil respiratory carbon loss was significantly higher than either single factor alone, but without a concomitant decline in soil carbon storage. Observations suggest that when soils are exposed to both factors simultaneously, plant carbon inputs to the soil are enhanced, counterbalancing soil carbon loss and helping maintain soil carbon stocks near control levels. This has implications for both atmospheric CO2 emissions and soil fertility and shows that coupling two important global change drivers results in a distinctive response that was not predicted by the behaviour of the single factors in isolation.

Carbon Dioxide Adsorption over Activated Biocarbons Derived from Lemon Peel.

The rising concentration of CO2 in the atmosphere is approaching critical levels, posing a significant threat to life on Earth. Porous carbons derived from biobased materials, particularly waste byproducts, offer a viable solution for selective CO2 adsorption from large-scale industrial sources, potentially mitigating atmospheric CO2 emissions. In this study, we developed highly porous carbons from lemon peel waste through a two-step process, consisting of temperature pretreatment (500 °C) followed by chemical activation by KOH at 850 °C. The largest specific surface area (2821 m2/g), total pore volume (1.39 cm3/g), and micropore volume (0.70 cm3/g) were obtained at the highest KOH-to-carbon ratio of 4. In contrast, the sample activated with a KOH-to-carbon ratio of 2 demonstrated the greatest micropore distribution. This activated biocarbon exhibited superior CO2 adsorption capacity, reaching 5.69 mmol/g at 0 °C and 100 kPa. The remarkable adsorption performance can be attributed to the significant volume of micropores with diameters smaller than 0.859 nm. The Radke-Prausnitz equation, traditionally employed to model the adsorption equilibrium of organic compounds from liquid solutions, has been shown to be equally applicable for describing the gas-solid adsorption equilibrium. Furthermore, equations describing the temperature dependence of the Radke-Prausnitz equation's parameters have been developed.

Editorial: Advances in Mineral Carbonation

Mineral carbonation stands out as a prominent technology aimed at reducing atmospheric CO2 emissions, a major contributor to the greenhouse effect, through a variety of processes [...]

Enforced CO2 mineralization in anhydrite-rich rocks

Carbon dioxide (CO2) emission is a major contributor to global warming and climate change. Consequently, there is an urgent need to decrease the concentration of CO2 in the atmosphere and develop reliable methods for its storage. Subsurface carbon mineralization is an effective solution to mitigate atmospheric CO2 emissions. This study is focused on investigating anhydrite–CO2–brine interactions as a means of carbon storage in anhydrite-rich reservoirs. To achieve this, we conducted experiments involving anhydrite-rich rock exposed to supercritical CO2-brine environments. Notably, we conducted a novel mineral transformation of an outcrop anhydrite-rich rock within a static reactor, replicating subsurface conditions of high temperature (333 K) and pressure (104 bar). These experiments were conducted over fifteen days, both in the absence and presence of BaCl2. A comprehensive suite of mineralogical, elemental, and geochemical analyses was employed, including X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, ion chromatographic (IC) analysis, and micro-computed tomography (micro-CT) assessments. These analyses allowed capturing the changes occurring in the rock's structure and composition due to the CO2-brine interactions. The outcomes revealed that anhydrite, when exposed to supercritical CO2-saturated brine, undergoes a significant mineral transformation. This mineral modification leads to the formation of stable minerals, including calcite, siderite, feldspar, and barite. Consequently, there was an observed increase in total carbon (TC) content of up to 177 % for the CO2-brine treatment and 266 % for the CO2-brine + BaCl2 treatment. These findings provide valuable insights into the potential of anhydrite-based CO2 storage mechanisms.

Comparative study of direct solid-gas carbonation and direct aqueous carbonation for carbon capture and storage

Abstract Carbon dioxide (CO2) is a significant contributor to global warming and environmental issues, necessitating the development of practical storage solutions. As an alternative to CO2 storage in subsurface formations, mineral carbonation, which offers long-term CO2 storage and advantages like thermodynamics and energy economy, is gaining popularity. Also, the possible repurposing of carbonated solid waste in the building and construction industry contributes to the reduction of CO2. However, large-scale implementation of natural mineral carbonation remains a challenge. This study investigates the comparative advantages and disadvantages of direct solid-gas and direct aqueous carbonation, two carbon capture and storage (CCS) methods for combating atmospheric CO2 emissions. The research focuses on reaction kinetics, capture efficiency, recovery efficiency, leakage security, and cost-effectiveness. Both methods have the potential to capture CO2 efficiently, but they differ in their effectiveness and feasibility. Direct solid-gas carbonation exhibits higher reaction rates and capture efficiency, while direct aqueous carbonation has lower energy requirements and is easier to implement at ambient temperature and pressure. Further research is essential to fully understand the comparative merits and drawbacks of direct solid-gas and aqueous carbonation and devise strategies to minimize their environmental impact. Furthermore, to ensure economic feasibility, future research should focus on lowering CO2 sequestration costs, increasing the scale of captured CO2 usage in industrial processes, and developing a circular economy by transforming captured CO2 into valuable metal carbonates.

Accelerating CO2 Storage Site Characterization through a New Understanding of Favorable Formation Properties and the Impact of Core-Scale Heterogeneities

CO2 sequestration in deep geologic formations can permanently reduce atmospheric CO2 emissions and help to abate climate change. Target formations must undergo a time- and resource-intensive site evaluation process, assessing storage capacity, environmental safety, and suitability for CO2 trapping via reactive transport models based on data from a limited number of core samples. As such, simulations are often simplified and omit heterogeneities in formation properties that may be significant but are not well understood. To facilitate more rapid site assessment, this work first defines the aquifer properties of favorable storage formations through the analysis of promising and active storage sites. Data show quartz is the most prevalent formation mineral with carbonate minerals, highly reactive with injected CO2, present in over 75% of formations. Porosity and permeability data are highly clustered at 10–30% and 10–1000 mD. Field-scale reactive transport simulations are then constructed and used to analyze CO2 trapping efficiency. The models consider porosity and carbonate mineral heterogeneity as well as the impacts of typical temperature gradients. Simulated sequestration efficiencies are compared to results from a comparable homogenous model to understand the implications of aquifer non-uniformities. The results show a lower sequestration efficiency in the homogeneous model during the injection phase. During the post-injection phase, the homogenization of porosity and carbonate mineralogy results in a higher sequestration efficiency. Incorporating the temperature gradient also increases the sequestration efficiency. Importantly, the maximum deviation between the homogeneous and heterogeneous simulations at the end of the 50-year study period is only ~10%. Larger impacts may be incurred for properties outside the defined, promising ranges suggested here.

Metal bioaccumulation and effects of olivine sand exposure on benthic marine invertebrates

Due to the anthropogenic increase of atmospheric CO2 emissions, humanity is facing the negative effects of rapid global climate change. Both active emission reduction and carbon dioxide removal (CDR) technologies are needed to meet the Paris Agreement and limit global warming to 1.5 °C by 2050. One promising CDR approach is coastal enhanced weathering (CEW), which involves the placement of sand composed of (ultra)mafic minerals like olivine in coastal zones. Although the large-scale placement of olivine sand could beneficially impact the planet through the consumption of atmospheric CO2 and reduction in ocean acidification, it may also have physical and geochemical impacts on benthic communities. The dissolution of olivine can release dissolved constituents such as trace metals that may affect marine organisms. Here we tested acute and chronic responses of marine invertebrates to olivine sand exposure, as well as examined metal accumulation in invertebrate tissue resulting from olivine dissolution. Two different ecotoxicological experiments were performed on a range of benthic marine invertebrates (amphipod, polychaete, bivalve). The first experiment included acute and chronic survival and growth tests (10 and 20 days, respectively) of olivine exposure while the second had longer (28 day) exposures to measure chronic survival and bioaccumulation of trace metals (e.g. Ni, Cr, Co) released during olivine sand dissolution. Across all fauna we observed no negative effects on acute survival or chronic growth resulting solely from olivine exposure. However, over 28 days of exposure, the bent-nosed clam Macoma nasuta experienced reduced burrowing and accumulated 4.2 ± 0.7 μg g ww−1 of Ni while the polychaete Alitta virens accumulated 3.5 ± 0.9 μg g ww−1 of Ni. No significant accumulation of any other metals was observed. Future work should include longer-term laboratory studies as well as CEW field studies to validate these findings under real-world scenarios.

From Physics to Environmental Policy: Exploring Boltzmann Distribution for Carbon Trading Permit Allocation

Combating climate change and reducing atmospheric CO2 emissions are imperative. While carbon trade, including taxes and trading systems, has been proposed, the allocation of initial permits is challenging. This study addresses this issue, exploring the application of the Boltzmann distribution for carbon emission permit allocation in carbon trading. The Boltzmann distribution method uniquely considers each country's environmental and economic contexts, assigning more responsibility to nations with larger populations and higher emissions, and providing incentives to lower-emission countries. This promotes fairness in global climate change efforts and influences national environmental policies. High-emission countries like China receive a high number of permits, encouraging stronger environmental policies, whereas countries with lower emissions, such as Italy, benefit from additional permits as compared to conventional distribution models, bolstering their existing environmental conservation. This paper applies the Boltzmann distribution to eight countries, considering population, economic size, and CO2 emissions. It effectively balances permits between egalitarianism (population-based) and sovereignty (emission-based) principles, suitable for international carbon trading. This flexible approach provides a practical framework for international emissions rights allocation along with potential applications in broader contexts. Implementation of the Boltzmann distribution in real-world policy faces challenges due to the dynamic nature of international politics and economics. This research offers insights into the process of integrating this method into existing environmental policy frameworks, demonstrating its potential as a tool for enhancing global environmental sustainability. Future research should explore its application in the complex international political and economic environment, furthering its role in global climate policy.

Heterogeneous nucleation of CO2 hydrate: A thermodynamics analysis considering effects of wall characteristics and solution activity

The massive emission of greenhouse gas CO2 has significant effects on global climate and environment, causing worldwide concern. It has been proposed to store CO2 in clathrate hydrates as a possible strategy for reducing atmospheric CO2 emission. Nevertheless, the CO2 hydrate formation rate is slow and its associated heterogeneous nucleation mechanisms are not well understood, which limit commercial applications of this technology. This study developed a thermodynamic model based on the change in availability function approach, considering effects of surface characteristics (including surface topography, roughness, curvature radius, and wettability), and CO2 dissolution on the solution's activity. The critical nucleation radius and energy barrier of CO2 hydrate nucleation are determined. Effects of pressure, temperature, wall characteristics and solution activity on the nucleation radius of CO2 hydrate are discussed. The results of this paper contribute to advancing carbon capture and storage technology based on hydrate methods.

Electrocatalytic Activity of CO2 Reduction to CO on Cadmium Sulfide Enhanced by Chloride Anion Doping.

The electrocatalytic CO2 reduction (ECR) to produce valuable fuel is a promising process for addressing atmospheric CO2 emissions and energy shortages. In this study, Cl-anion doped cadmium sulfide structures were directly fabricated on a nickel foam surface (Cl/CdS-NF) using an in situ hydrothermal method. The Cl-anion doping could significantly improve ECR activity for CO production in ionic liquid and acetonitrile mixed solution, compared to pristine CdS. The highest Faradaic efficiency of CO is 98.1 % on a Cl/CdS-NF-2 cathode with an excellent current density of 137.0 mA cm-2 at -2.25 V versus ferrocene/ferrocenium (Fc/Fc+ , all potentials are versus Fc/Fc+ in this study). In particular, CO Faradaic efficiencies remained above 80 % in a wide potential range of -2.05 V to -2.45 V and a maximum partial current density (192.6 mA cm-2 ) was achieved at -2.35 V. The Cl/CdS-NF-2, with appropriate Cl anions, displayed abundant active sites and a suitable electronic structure, resulting in outstanding ECR activity. Density functional theory calculations further demonstrated that Cl/CdS is beneficial for increasing the adsorption capacities of *COOH and *H, which can enhance the activity of the ECR toward CO and suppress the hydrogen evolution reaction.

Atmospheric CO2 emissions and ocean acidification from bottom-trawling

Trawling the seafloor can disturb carbon that took millennia to accumulate, but the fate of that carbon and its impact on climate and ecosystems remains unknown. Using satellite-inferred fishing events and carbon cycle models, we find that 55-60% of trawling-induced aqueous CO2 is released to the atmosphere over 7-9 years. Using recent estimates of bottom trawling’s impact on sedimentary carbon, we found that between 1996-2020 trawling could have released, at the global scale, up to 0.34-0.37 Pg CO2 yr-1 to the atmosphere, and locally altered water pH in some semi-enclosed and heavy trawled seas. Our results suggest that the management of bottom-trawling efforts could be an important climate solution.

Green synthesis of fluorescent carbon quantum dots from bagasse: inhibition of calcium sulphate scales

The conversion of biomass waste generated in large amounts to value-added materials and energy can reduce environmental pollution, atmospheric CO2 emissions and waste disposal costs in a circular economy.

Carbon dioxide resource recycling technology: Analysis and prospects of Mo-based catalyst performance in low-carbon alcohol synthesis

This study addresses the escalating issue of atmospheric CO2 emissions and climate change, exacerbated by the increased use of fossil fuels. It explores the synthesis of low-carbon alcohols as a viable method to utilize excess atmospheric CO2, meeting the growing demand for sustainable fuel alternatives. The research focuses on the challenges of activating CO2, often requiring conversion to CO via a reverse water gas shift reaction (RWGS) prior to alcohol synthesis. Through detailed case studies, this review investigates the factors influencing the catalytic efficiency of molybdenum-based (Mo-based) catalysts in alcohol synthesis from CO. Key aspects such as the addition of additives, support types, preparation methods, and the catalyst’s composition are analyzed for their impact on catalyst selectivity and activity. This comprehensive review not only highlights the critical conditions for optimizing catalytic reactions but also contributes to the development of effective strategies for reducing greenhouse gases through innovative catalytic technologies.

Response of vegetation carbon sequestration potential to the effectiveness of vegetation restoration in karst ecologically fragile areas in Guizhou, southwest China

In the southwest karst areas of China, changes in overlying vegetation due to ecological restoration cause considerable carbon sequestration (CS). Assessing the CS potential of vegetation restoration in this areas is crucial for promoting the optimization and regulation of regional vegetation restoration(VR) policies. This study is based on net primary productivity, maximum vegetation coverage and average vegetation coverage. Using the VR effectiveness index (Ej) to quantitatively evaluate the spatiotemporal characteristics of VR effectiveness, quantifying the spatiotemporal pattern of vegetation restoration CS using the vegetation photosynthetic CS model, and clarifying the main driving mechanisms of vegetation restoration CS.This results showed that more than 54.25 % of the studied area in the ecologically fragile areas has achieved significant VR (Ej ≥ 20) from 2000 to 2020. The spatial distribution of vegetation CS intensity and potential was higher in the southwest than in the northeast. Moreover, there was a strong spatial correlation between the areas with greater vegetation CS densities and the areas with poor natural background conditions, showing that the effectiveness of ecological restoration and economic growth complement each other. The correlation between the potential for vegetation CS and the current value of vegetation cover was r = 0.06 (p < 0.05) and the correlation with the magnitude of change in vegetation cover was r = 0.38 (p < 0.05), which indicates that vegetation CS has a greater potential where the magnitude of vegetation greening is greater. The greening range of vegetation was constrained by the natural background environment in ecologically fragile areas, and the continuous enhancement of positive feedback intervention and weakening of negative feedback tended to promote the greening range of vegetation on the ground surface and increased the CS potential. This results provide a reference for the long-term goal of “carbon neutrality” in response to VR and CS in ecologically fragile areas to offset atmospheric CO2 emissions.

Liquid flow glazing contributes to energy-efficient buildings: A review

This work gives a precise review of the researches completed on the energy conservation characteristics of liquid flow glazing. Its energy saving and environmental benefits under various design and operation conditions, contributions with renewable energy utilization, as well as application in zero energy buildings are timely explored and summarized. Its advantages lie in the reduction of thermal transmission between the indoor and outdoor environments, the beneficial thermal collection, and the tactful utilization of renewable energy. The optical and thermal properties, as well as the energy performance of liquid flow glazing were found much affected by the glazing and fluid properties, the window configuration, and the operating conditions. These are consequently linked to the degree of electricity saving, the decrease in atmospheric CO2 emission, and the shortened life cycle payback time. The integrated use of solar and geothermal energy in liquid flow glazing systems is also addressed. This leads to more practical studies on the applications in zero energy buildings, such as control, real-time monitoring, and energy management strategies of liquid flow glazing system. In essence, the development of an evaluation platform or database, with systemic classification of liquid flow glazing categories plus the corresponding graded energy saving characteristics, is deemed helpful to the building professionals in meeting the zero energy buildings development targets.

CO2 monitoring associated with the quality of soybean grains stored in different moisture contentes

The objective of this study was to quantify the levels of CO2 produced by soybeans stored at room temperature in a prototype silo, with initial moisture contents of 12, 14, and 16% (w.b.), as well as to evaluate the quality of the product over storage. Analyses of the moisture content, ash, proteins, lipids, color, germination, and electrical conductivity were performed. In the atmosphere in the silos, the amount of CO2, relative humidity, and temperature were monitored every hour using a CO2 meter data logger. Grain quality evaluations took place at four storage times (0, 30, 60, and 90 days). Analyses were performed in triplicate, and data were analyzed using analysis of variance and regression, adopting the 5% level of significance. The moisture contents, protein, lipids, germination, and color were reduced over time, resulting in a loss of grain quality. Soybeans initially stored with 16% (w.b.) of initial moisture content showed greater losses associated with the rise in the levels of CO2. The rise in CO2 emission in the internal atmosphere of the silo signals the beginning of grain deterioration and can be used as a decision-making tool, aiming at preventing and reducing losses in product quality over storage.