Atmospheric Carbon Dioxide Levels Research Articles (Page 1)

Recent advances in biocathode materials and configurations for reactor applications in microbial electrosynthesis of CO2.

Abstract Rising atmospheric carbon dioxide (CO 2 ) levels exceeding 400 ppm since 2013 and reaching 36.6 billion tons in 2022 due to fossil fuel combustion have accelerated global climate change, contributing to a 1.2 °C rise in temperature and triggering serious environmental issues such as ocean acidification and extreme weather events. Among emerging mitigation strategies, electrochemical CO₂ reduction offers a promising route to convert CO 2 into valuable fuels and chemicals. This review highlights recent advances in nanomaterial-based CO 2 conversion, focusing on electrochemical processes enabled by catalysts such as metal and metal oxide nanoparticles, graphene, carbon nanotubes, and carbon quantum dots. These nanostructures provide large surface areas, tunable electronic properties, and improved catalytic performance. In-operando characterization techniques including transmission electron microscopy (TEM), X-ray absorption spectroscopy (XAS), Raman spectroscopy, infrared spectroscopy (IR), and electrochemical impedance spectroscopy (EIS) are discussed for their role in offering real-time mechanistic insights that support rational catalyst design. The review also considers photocatalytic, thermocatalytic, and plasma-assisted processes to provide a broader perspective on CO 2 utilization. Strategies such as surface functionalization, hybrid material development, and strain engineering are examined for enhancing efficiency and durability. The review concludes by highlighting challenges and future directions for integrating nanomaterials into sustainable, carbon-neutral technologies. Graphical Abstract

Due to the rising atmospheric carbon dioxide levels driven by human activity, extensive scientific efforts have been dedicated to developing methods aimed at reducing its concentration in the atmosphere. A novel approach involves using hydrates as a long-lasting reservoir of CO2 sequestration. This review provides an initial overview of hydrate characteristics, their formation mechanisms, and the experimental techniques commonly employed for their characterization, including X-ray, Raman spectroscopy, cryoSEM, DSC, and molecular dynamic simulation. One of the main challenges in CO2 sequestration via hydrates is the requirement of high pressures and low temperatures to stabilize CO2 molecules within the hydrate crystalline cavities. However, deviations from classical temperature-pressure phase diagrams observed in natural and engineered environments can be explained by considering that hydrate stability and formation are primarily governed by chemical potentials, not just temperature and pressure. Activity, which reflects concentration and non-ideal interactions, greatly influences chemical potentials, emphasizing the importance of solution composition, salinity, and additives. In this context the role of promoters and inhibitors in facilitating or hindering hydrate formation is discussed. Furthermore, the review presents an overview of the impact of marine sediments and naturally occurring compounds on CO2 hydrate formation, along with the sampling methodologies used in sediments to determine the composition of these natural compounds. Special attention is given to the effect and chemical characterization of dissolved organic matter (DOM) in marine aquatic environments. The focus is placed on the key roles of various natural occurring molecules, such as amino acids, protein derivatives, and humic substances, along with the analytical techniques employed for their chemical characterization, highlighting their central importance in the CO2 gas hydrates formation.

Harnessing the biomolecular mechanisms of marine biomineralisation for carbon sequestration.

Hyperspectral inversion of soil organic matter based on improved ensemble learning method.

ABSTRACTRising atmospheric carbon dioxide (CO₂) levels are expected to enhance biomass and yield in C3 crops. However, these benefits are accompanied by significant reductions in the concentrations of essential nutrients in both foliar and edible tissues, posing potential global nutritional challenges. In this study, we grew three soybean cultivars (Clark, Flyer, and Loda) in ambient ( ~ 438 ppm) and elevated CO₂ ( ~ 650 ppm) conditions using open top chambers and measured changes in leaf‐level physiological responses, biomass accumulation, and nutrient concentrations across developmental stages. Elevated CO₂ increased carbon assimilation and decreased stomatal conductance, which led to an increase in seed yield, while root biomass remained unchanged. Seed nutrient concentrations, particularly iron (Fe), zinc (Zn), manganese (Mn), boron (B), phosphorus (P), potassium (K), and magnesium (Mg), decreased at maturity. We hypothesize that reductions in seed mineral concentration resulted from enhanced carbon assimilation and biomass accumulation without a concomitant response in root biomass and nutrient uptake. This constrained the plant's ability to maintain nutrient status with increased yield at elevated CO₂, and this response was conserved across the cultivars included in this study. Future work is needed to further understand the molecular mechanisms associated with these physiological responses at elevated CO2 in soybean.

Climate change can affect rice production through changes in temperature, precipitation patterns, extreme weather events, and atmospheric carbon dioxide levels. A statistical model can be used to understand the correlation between rice production and factors that affect it. The existence of some patterns that are formed from independent variables and others that do not show data patterns due to volatility in weather element data makes semiparametric regression modeling more appropriate. In forming a parametric model, the data pattern needs to be regular to make the model more precise. Irregular data patterns are more appropriately modeled with nonparametric regression models. The existence of several patterns formed from independent variables to their dependent variables, and several others, does not show a particular pattern due to the volatility in climate data, making truncated spline semiparametric regression modeling more appropriate to use. This research aims to model rice production in several regions in East Java Province in 2022 using a semiparametric regression model. The data used were from the Meteorology, Climatology, and Geophysics Agency and the Central Statistics Agency for East Java Province in 2022. The response variable is the rice production (tons) in 2022 in Tuban, Gresik, Nganjuk, Malang, Banyuwangi, and Pasuruan Regency (Y). The predictor variables are paddy harvested area (hectares), average temperature (℃), humidity (percent), and rainfall (mm). The semi-parametric spline truncated regression model is obtained by combining the parametric and non-parametric models based on truncated splines. The analysis showed a spline truncated semiparametric regression model with a combination of knot points (3,3,1) with a minimum GCV value of 12,642,272. The variables significantly affecting rice production were rice harvest area, temperature, air humidity, and rainfall, with an adjusted value of 98.522%.

The rising level of atmospheric carbon dioxide (CO2) is a major driver of climate change, highlighting the need to develop carbon capture and storage (CCS) technologies quickly. This paper offers a comparative review of three main groups of porous adsorbent materials—zeolites, metal–organic frameworks (MOFs), and activated carbons—for their roles in CO2 capture and long-term storage. By examining their structural features, adsorption capacities, moisture stability, and economic viability, the strengths and weaknesses of each material are assessed. Additionally, five different methods for delivering these materials into depleted oil and gas reservoirs are discussed: direct suspension injection, polymer-assisted transport, foam-assisted delivery, encapsulation with controlled release, and preformed particle gels. The potential of hybrid systems, such as MOF–carbon composites and polymer-functionalized materials, is also examined for improved selectivity and durability in underground environments. This research aims to connect materials science with subsurface engineering, helping guide the selection and use of adsorbent materials in real-world CCS applications. The findings support the optimization of CCS deployment and contribute to broader climate change efforts and the goal of achieving net-zero emissions. Key findings include CO2 adsorption capacities of 3.5–8.0 mmol/g and surface areas up to 7000 m2/g, with MOFs demonstrating the highest uptake and activated carbons offering cost-effective performance.

Anthropogenic greenhouse gas emissions have a detrimental impact on the carbonsequestration by the oceans. Pteropods, a crucial component of the ocean's planktic community, secrete aragonite shells that are sensitive to increasing atmospheric carbon dioxide levels, making them the first indicators of ocean acidification. Therefore, pteropods are often used to observe the changes in aragonite compensation depth (ACD). Intriguingly, in the majorparts of the northern Indian Ocean, the chemically defined ACD is < 800m, but pteropods have been reported in surface sediments collected from much deeper depths in the same region, which raises questions about the use of pteropods to trace ACD in this area. To address this ambiguity, we conducted a systematic and detailed evaluation of pteropods to trace the changes in ACD in the western Bay of Bengal, which is the first-ever such study. The pteropods population dominated by Heliconoides inflatuswas low on the inner shelf, and isolated pockets of high pteropod abundance were restricted to the upper slope. Based on the pteropod abundance in the surface sediments and the ratio of pteropods to planktic foraminifera, we report the baseline ACD in the western Bay of Bengal at ~ 500m. The aragonite compensation depth based on the pteropod abundance in the surface sediments correlates well with the chemically defined ACD in this region. These findings will help to assess the impact of ocean acidification on aragonite compensation depth in the western Bay of Bengal.

Climate change, characterized by rising atmospheric carbon dioxide (CO2) levels and increasing global temperatures, poses significant threats to aquatic ecosystems. This study examines the impact of elevated CO2 concentrations and water temperature on the growth, survival, and hematological condition of mahseer juveniles. A controlled experiment was conducted to analyze growth parameters, including specific growth rate (SGR), relative growth rate (RGR), feed conversion ratio (FCR), and hematological indices across varying CO2 and temperature conditions. The findings indicate that CO2 levels significantly influence fish weight, with higher concentrations promoting growth up to a threshold. Elevated temperature negatively affects fish weight gain, particularly at extreme levels. Hematological responses suggest that prolonged exposure to high CO2 and temperature alters blood parameters, indicating physiological stress. The interaction between CO2 and temperature suggests that optimal growth occurs at high CO2 and moderate temperatures, whereas excessive warming exacerbates metabolic stress and mortality. These results provide essential insights for sustainable aquaculture practices and conservation strategies in the face of climate change. The significance of these findings extends to aquaculture industries aiming to optimize fish production under changing environmental conditions.

Natural processes collectively balance the global carbon cycle, effectively controlling atmospheric carbon dioxide (CO2) levels. However, excessive CO2 emissions due to industrialization and population growth have disrupted natural processes by increasing the atmospheric CO2 concentration. To address this issue, CO2 capture and conversion have been implemented. Metal-organic frameworks (MOFs)/coordination polymers (CPs) with bioligands, such as amino acids and nucleobases, are receiving much interest. However, bio-MOFs are not much reported due to the lack of control over their coordination with metal ions. In this work, we have developed an adenine-tagged Mn-CP with dominant basic sites, [Mn(IPT2-)(Ade)(DMF)]n (IPT2- = isophthalate; Ade = adenine; DMF = N,N'-dimethylformamide). The analysis of isosteric heat (Qst) of CO2 adsorption supported the presence of strong interactions between CO2 and Mn-CP. Mn-CP demonstrated moderate to outstanding performance in coupling CO2 with smaller and larger epoxides at ambient pressure under neat conditions. The thermodynamic activation parameters indicate that Mn-CP operates through an associative mechanism (ΔS⧧ = -283.4 J mol-1 K-1), with a reduced kinetic barrier characterized by ΔH⧧ of 17.28 kJ mol-1 and Ea of 20.5 kJ mol-1. The catalytic efficiency of Mn-CP was particularly notable in the coupling reaction of epichlorohydrin and CO2, yielding 92% of the corresponding cyclic carbonate under atmospheric pressure.

Eucalyptus plantations and agroforestry systems have garnered significant interest due to their ability to capture carbon and mitigate climate change. This review assesses the carbon sequestration potential of eucalyptus-based systems, emphasizing their effectiveness in lowering atmospheric carbon dioxide (CO₂) levels. In India, eucalyptus plantations exhibit carbon sequestration rates between 9.62 and 11.4 Mg ha-1 per year, with a total accumulation of up to 237.2 Mg C ha-1 over their lifespan. Various factors, including plantation age, soil quality and management strategies, influence this potential. Older plantations have greater carbon storage capacity, making them vital for long-term mitigation efforts. In addition to monoculture plantations, agroforestry systems integrating eucalyptus, such as silvi-pastoral, agri-silvicultural and boundary plantations, provide a comprehensive approach to carbon sequestration. These systems not only enhance carbon accumulation in both biomass and soil but also offer economic and environmental advantages, such as improved soil health, biodiversity conservation and livelihood support for farmers. Short-rotation eucalyptus plantations and agroforestry models can capture up to 10 Mg C ha-1 annually, contributing significantly to long-term carbon storage. Notably, eucalyptus species have also demonstrated potential for bio drainage in waterlogged areas due to their high transpiration capacity, though concerns regarding excessive water use have led to regulatory restrictions in certain Indian states. In regions facing land-use constraints, incorporating eucalyptus into agroforestry serves as a viable solution for sustainable carbon management. However, while eucalyptus plantations offer significant carbon sequestration benefits, their high water demand and potential groundwater depletion necessitate careful site selection, appropriate species choice and sustainable management to mitigate adverse effects. This review underscores the crucial role of eucalyptus plantations and agroforestry systems in global carbon sequestration initiatives. By increasing carbon storage in biomass and soil, these systems present an effective strategy for addressing climate change while delivering socio-economic and environmental benefits. Further research and the development of optimized management practices are needed to maximize their carbon sequestration potential while ensuring ecological sustainability.

In this paper, we develop a rational bubble model to quantify the susceptibility of global stock markets to future temperature rises. The approach builds on existing theory incorporating the unpredictable timing of future Black-Swan events alongside price risks that increase in line with global temperature. An alternative specification where climate-change risks are instead linked to atmospheric carbon dioxide levels is also given. The approach offers simplicity, transparency and allows national-level effects to be estimated. In the short term, prices are artificially inflated and volatility artificially deflated as temperatures rise. This is in-line with previous work suggesting carbon-related risks are underpriced by markets. We use our model to estimate stock market exposure to future climate-change risks given future global temperature rises and increases in atmospheric . The potential effects are considerable once global temperatures increases beyond above preindustrial levels. We find that climate-change risks are priced in by certain G7 stock markets but not in smaller markets. Estimates of stock market losses directly attributable to global temperature rises up to above preindustrial levels are alsogiven.

Abstract Geologic carbon storage is widely recognized as a critical strategy for mitigating atmospheric carbon dioxide (CO2) levels, yet its effectiveness is contingent upon the integrity of caprock formations that prevent CO2 leakage. This study investigates the sealing potential of three representative caprock formations—Eau Claire Shale, Maquoketa Shale, and Opalinus Clay—by employing a comprehensive set of experimental approaches. Laboratory assessments include permeability tests, stepwise CO2 injection, imbibition experiments, and porosimetry‐based estimation to evaluate the sealing potential of heterogeneous geomaterials. It appears that within each formation, sand‐rich specimens exhibit significantly higher permeability and lower breakthrough pressures compared to their clay‐rich counterparts, underscoring the influence of the lithological variation. An indirect method based on pore structure analysis tends to underestimate the sealing capacity, highlighting discrepancies caused by the confinement, pore structure anisotropy, and variations in geochemical interactions. A statistical analysis based on the data set from this study and the literature reveals that CO2 breakthrough pressure is positively correlated with the clay content, negatively correlated with the permeability and dominant pore size, and independent of its porosity. The sealing number is introduced to provide a quantitative framework for evaluating the sealing integrity of the tested caprock formations to withstand buoyant forces. This study highlights the critical role of heterogeneities in determining caprock sealing potential and emphasizes the importance of direct measurements, particularly the use of the stepwise method, for accurate assessment. Advanced imaging and geophysical monitoring, coupled with multi‐scale experiments, are recommended to enhance the reliability of heterogeneous caprock integrity assessments.

Rising atmospheric carbon dioxide (CO₂) levels are profoundly altering Earth's hydrological systems. To contextualize these changes, insights from past warm intervals are essential. This study synthesizes plant-derived proxy records from the Indian subcontinent to reconstruct hydrological patterns from the Late Cretaceous through the Paleogene—a period marked by India's tectonic drift from Gondwanaland to Asia. Results indicate a persistently warm and humid climate with high mean annual precipitation and pronounced seasonal rainfall from the latest Cretaceous into the early Paleocene. Throughout the early to middle Paleogene, including hyperthermal events such as the PETM, ETM2, and MECO, plant assemblages reflect changes in hydrological cycles and biotic turnover. Notably, these intervals saw a rise in deciduous taxa, signaling heightened seasonality and prolonged dry periods despite global warming. The Early Eocene Climatic Optimum (EECO) stands out for its sustained warm and humid conditions that supported stable tropical evergreen rainforests. The long-standing monsoonal regime observed during Late Cretaceous to early Oligocene more closely resembled the present-day Indonesian–Australian Monsoon than the modern South Asian Monsoon, which likely developed following Himalayan uplift in the Neogene. This synthesis highlights the complex interplay between global warming, seasonal precipitation patterns, and vegetation dynamics, reinforcing India's key role in understanding Cenozoic climate–biosphere evolution.

Abstract High‐resolution continental temperature records from geological archives are crucial in order to evaluate temperature dynamics under fundamentally different climate conditions than today. Particularly the warm early to middle Eocene (∼56–40 million years ago) has become the focus of paleoclimate studies with the intention of quantifying temperatures under high atmospheric carbon dioxide (pCO2) levels. However, detailed proxy reconstructions of land temperature variability during the Eocene “greenhouse” are currently lacking for large parts of the continents. Here we present a ∼430 thousand‐year high‐resolution continental temperature record, reconstructed from terrestrial biomarkers preserved in the maar sediments of the UNESCO World Heritage Site “Messel Fossil Pit,” Germany during the earliest middle Eocene of Central Europe (∼47.7–47.2 million years ago). We found that continental temperatures ranged between ∼21 and 28°C, but shifted from a highly variable (fluctuations up to ∼5°C) temperature pattern (∼155 thousand years) toward a more constant temperature state (∼145 thousand years) through the time period covered here. The shift in temperature history was possibly associated with varying orbital configurations or the concurrent initiation of North Atlantic seaway changes. Moreover, we identified a pronounced warming at ∼47.5 million years, that coincides with negative benthic oxygen and carbon isotopic excursions in the time‐equivalent marine stacks, indicating that the maar lake recorded a previously unknown “hyperthermal‐like” global warming event.

Catalyst breakthroughs in methane dry reforming: Employing machine learning for future advancements

Forest ecosystems play a vital role in sequestering carbon, primarily functioning as terrestrial carbon sinks that significantly help reduce atmospheric carbon dioxide levels. The north-eastern states of India (comprising an area of approximately 168,903 km²) collectively account for a substantial portion of the country’s forest resources (23.61% of the total forest cover). The present paper attempts to explore the forest types, patterns of biomass distribution, and carbon storage potential across Northeast India, emphasizing on their ecological importance and conservation needs. It also examines the destructive, non-destructive, and remote sensing &amp; GIS-based biomass estimation techniques employed by various researchers to identify existing research gaps. This amalgamated data from various methodologies, provides an all-inclusive appraisal of biomass carbon across the eight North-eastern states of India.

The need for practical carbon capture and storage technologies increases as levels of atmospheric carbon dioxide continue to rise. Geological carbon storage, which is a sequestration of CO2 in subsurface formations, has great potential. This paper explores the potential of the Indus Basin in Pakistan for geological carbon storage and also highlights the role of 4D X-ray tomography as an advanced monitoring and characterization technique. Indus Basin is rich in various sedimentary formations, including the Lower Goru Formation, Sui Main Limestone, and others with reservoir characteristics. International case studies demonstrate the use of 4D X-ray tomography in visualizing and quantifying CO2 behavior in porous media which provides insights into wetting behavior, mineral interactions, and flow dynamics. The objective of this research is to evaluate the feasibility and optimization of the CO2 storage process in specific Indus Basin reservoirs by using 4D X-ray tomography. This further aims to drive the attention towards the addressment of reservoir heterogeneity, long-term CO2 fate, and integrating micro-scale tomography data with larger-scale reservoir simulations to advance carbon storage initiatives in Pakistan.

&lt;p&gt;Due to the widespread use of fossil fuels, atmospheric levels of carbon dioxide (CO₂), a major contributor to climate change, have increased dramatically. Through the simulation of a two-dimensional (2D), bovine carbonic anhydrase (bCA)-mediated mechanism, this work presents a novel approach method for CO₂ capture using a membrane contactor; the technique uses aqueous carbonate solution as a chemical solvent. It is tested both with and without bCA. The influence of important parameters on the CO₂ capture performance, such as gas flow rate, liquid flow rate, and bCA concentration in both counter- and co-current flow, are investigated. The results show that the addition of 5 mg L⁻¹ bCA improves the removal efficiency by 24%; it is found that increasing the gas flow rate of CO₂ from 10 mL min⁻¹ to 30 mL min⁻¹ reduces the CO₂ removal from 60.47% to 23.94%, whereas with 5 mg L⁻¹ bCA, increasing the gas flow rate of CO₂ from 10 mL min⁻¹ to 30 mL min⁻¹ reduces the CO₂ removal from 84.09% to 46.85%. Increasing the liquid flow rate from 10 mL min-1 to 30 mL min-1 increases the CO2 removal from 60.47% to 87.06% without the addition of bCA; with 5 mg L-1 bCA, the CO2 removal increases from 84.06% to 95.04%. The counter-current is better than the co-current by a 4% improvement. The effect of the bCA enzyme on CO₂ capture is limited by the availability of CO₂ (the substrate) and the catalytic capacity of the enzyme. Maximum CO₂ removal efficiency, approaching almost total removal, is achieved at an enzyme concentration of approximately 30 mg L⁻¹ for the same CO₂ load.&lt;/p&gt;