Atmospheric CO2 Concentration Research Articles

Engineering CALF-20/graphene oxide nanocomposites for enhancing CO2/N2 capture performance

Ever-increasing atmospheric CO2 concentrations has necessitated the development of novel and cost-effective nanostructured composites with favorable physicochemical properties. Recently, the potential of metal-organic framework (MOF)-based nanocomposites towards boosting CO2 capture capability has become apparent indicating the importance of the relationship between their structure and properties. Herein, a novel nanocomposite of zinc-based CALF-20 MOF hybridized with graphene oxide is successfully fabricated using the solvothermal method. The construction of the well-structured nanocomposite is confirmed by performing PXRD, BET, FTIR, FESEM/EDX, TEM, and TGA characterization analyses. CO2 and N2 adsorption capacities and CO2/N2 separation performance of these nanocomposites are evaluated by experiment and mathematical modeling for the first time. The CALF-20/GO interfacial interaction and CO2 adsorption mechanisms are also discussed. As the best-performing adsorbent, the CALF-20 containing 20 wt% GO indicates a 42.6 % increment in CO2 uptake at 1.6 bar and a 32.7 % enhancement in CO2/N2 selectivity at 1 bar and 298 K and 1.28 times more CO2 retention time in a fixed bed column compared to that of the pristine MOF. The results show that the MOF and GO form chemical bonds at the interface resulting in generating new pore structures and increasing the porosity which are mostly responsible for boosting CO2 capture capacity. Interestingly, no meaningful effect is observed by the variation of the zinc atomic concentration at the surface. The simple synthesis procedure and understanding the interfacial structure of the novel CALF-20/GO composite as a promising adsorbent for CO2 capture applications can provide new insights for future work.

Assessment of the Potential of Electrochemical Steps in Direct Air Capture through Techno-Economic Analysis.

Direct air capture (DAC) technologies are proposed to reduce the atmospheric CO2 concentration to mitigate climate change and simultaneously provide carbon as a feedstock independent of fossil resources. The currently high energy demand and cost of DAC technologies are challenging and could limit the significance of DAC processes. The present work estimates the potential energy demand and the levelized cost of capture (LCOC) of liquid solvent absorption and solid adsorption DAC processes in the long term. A consistent framework is applied to compare nonelectrochemical to electrochemical DAC processes and estimate the LCOC depending on the electricity price. We determine the equivalent cell voltage needed for the electrochemical steps to achieve comparable or lower energy demand than nonelectrochemical processes. The capital expenses (CapEx) of the electrochemical steps are estimated using analogies to processes that are similar in function. The results are calculated for a range of initial data of CapEx and energy demand to include uncertainties in the data.

Fabrication of indium doped Bi/Bi2O3 catalyst for efficiently selective electroreduction of carbon dioxide to formate

Highly selective electrocatalytic reduction of CO2 to formate is considered a valid route for alleviating the continuing increase in atmospheric CO2 concentration. Herein, Indium-doped Bi/Bi2O3 (In-Bi/Bi2O3) electrocatalyst grown in situ on carbon paper (CP) was obtained via a relatively simple one-step solvothermal synthesis method and utilized in CO2 reduction reaction (CO2RR) for formate production. The In-Bi/Bi2O3/CP exhibits superior Faradaic Efficiency for formate, i.e., FEformate = 96.3 %, and a partial current density of 6.74 mA cm−2 at −1.6 V (vs Ag/AgCl) in the H-type cell. Furthermore, FEformate of the electrode remains consistently above 90 % within long-term stability testing (60 h). By density functional theory (DFT) calculations, it is found that incorporating In into Bi/Bi2O3 can generate more active sites and facilitate the preferential adsorption of *OOCH intermediates, alleviating competitive adsorption of *H during CO2 reduction reaction (CO2RR), thereby accelerating formate production.

Effects of atmospheric CO2 concentration on transpiration and leaf elongation responses to drought in Triticum aestivum, Lolium perenne and Festuca arundinacea.

Leaf elongation is vital for Poaceae species' productivity, influenced by atmospheric CO2 concentration ([CO2]) and climate-induced water availability changes. Although [CO2] mitigates the effects of drought on reducing transpiration per unit leaf area, it also increases total leaf area and water use. These complex interactions associated with leaf growth pose challenges in anticipating climate change effects. This study aims to assess [CO2] effects on leaf growth response to drought in perennial ryegrass (Lolium perenne), tall fescue (Festuca arundinacea) and wheat (Triticum aestivum). Plants were cultivated in growth chambers with [CO2] at 200 or 800ppm. At leaf six to seven unfolding, half of the plants were subjected to severe drought treatment. Leaf elongation rate (LER) was measured daily, whereas plant transpiration was continuously recorded gravimetrically. Additionally, water-soluble carbohydrate (WSC) content along with water and osmotic potentials in the leaf growing zone were measured at drought onset, mid-drought and leaf growth cessation. Elevated [CO2] mitigated drought impacts on LER and delayed growth cessation across species. A positive correlation between LER and soil relative water content (SRWC) was observed. At the same SRWC, perennial grasses exhibited a higher LER with elevated [CO2], likely due to enhanced stomatal regulation. Despite stomatal closure and WSC accumulation, CO2 did not influence nighttime water potential or osmotic potential. The marked increase in leaf area across species resulted in similar (wheat and tall fescue) or higher (ryegrass) total water use by the experiment's end, under both watered and unwatered conditions. In conclusion, elevated [CO2] mitigates the adverse effects of drought on leaf elongation in three Poaceae species, due to its impact on plant transpiration. Overall, these findings provide valuable insights into CO2 and drought interactions that may help anticipate plant responses to climate change.

Research progress on the effects of elevated atmospheric CO2 concentration on CH4 emission and related microbial processes in paddy fields.

Paddy fields are recognized as significant sources of methane (CH4) emissions, playing a pivotal role in global climate change. Elevated atmospheric carbon dioxide (CO2) concentrations (e[CO2]) exert a profound influence on the carbon cycling of paddy fields. Understanding the effects of e[CO2] on CH4 emissions, as well as the underlying microbial processes, is crucial for enhancing carbon sequestration and reducing emissions in paddy fields. We reviewed the impacts of e[CO2] on CH4 emission in paddy fields, focusing on the activity, abundance, community structure, and diversity of carbon-cycling-related microbes. We also delineated the roles of various microbial processes in mitigating CH4 emissions under e[CO2], as well as the primary environmental determinants. Overall, the type of e[CO2] experimental platforms, duration of fumigation, concentration gradients, and the methods of CO2 enrichment all influence CH4 emissions from paddy fields. e[CO2] initially stimulates CH4 emissions, which may decrease over time, indicating an adaptability of the methane-emitting microbial community to e[CO2]. This response exhibits a trend of initial attenuation followed by an intensification of the positive effects on CH4 emissions. Experiments with abrupt increase of CO2 concentration might overestimate CH4 emissions. The impact of e[CO2] on microbial processes is predominantly characterized by enhanced activities and abundance of methanogens, aerobic and anaerobic methanotrophs. It significantly alters the community composition and diversity of methanotrophs, with minimal effects on methanogens and anaerobic methanotrophic communities. Finally, we outlined future research directions: 1) Integrated investigations into the effects of e[CO2] on CH4 emissions, methanogenesis, and both aerobic and anaerobic methanotrophs in paddy fields could elucidate the mechanisms underlying the impacts of climate change on CH4 emissions; 2) Long-term studies are essential to understand the mechanisms of e[CO2] on CH4 emissions and associated microbial processes more accurately and realistically; 3) Multi-scale (temporal and spatial), multi-factorial (CO2 concentration, temperature, atmospheric nitrogen deposition, and water management practices), and multi-methodological (observational, data, and model integration) research is necessary to effectively reduce the uncertainties in assessing the response of CH4 emissions in paddy fields and related microbial processes to e[CO2] under future climate change scenarios.

Bio-Char Used for Carbon Sequestration and to Balance the CO2 Concentration in Atmosphere: A Review

Bio-Char Used for Carbon Sequestration and to Balance the CO2 Concentration in Atmosphere: A Review

Controls on Early Cretaceous South Atlantic Ocean circulation and carbon burial – a climate model–proxy synthesis

Abstract. Black shale sediments from the Barremian to Aptian South Atlantic document the intense and widespread burial of marine organic carbon during the initial stages of seafloor spreading between Africa and South America. The enhanced sequestration of atmospheric CO2 makes these young ocean basins potential drivers of the Early Cretaceous carbon cycle and climate perturbations. The opening of marine gateways between initially restricted basins and related circulation and ventilation changes are a commonly invoked explanation for the transient formation and disappearance of these regional carbon sinks. However, large uncertainties in palaeogeographic reconstructions limit the interpretation of available palaeoceanographic data and prevent any robust model-based quantifications of the proposed circulation and carbon burial changes. Here, we present a new approach to assess the principal controls on the Early Cretaceous South Atlantic and Southern Ocean circulation changes under full consideration of the uncertainties in available boundary conditions. Specifically, we use a large ensemble of 36 climate model experiments to simulate the Barremian to Albian progressive opening of the Falkland Plateau and Georgia Basin gateways with different configurations of the proto-Drake Passage, the Walvis Ridge, and atmospheric CO2 concentrations. The experiments are designed to complement available geochemical data across the regions and to test circulation scenarios derived from them. All simulations show increased evaporation and intermediate water formation at subtropical latitudes that drive a meridional overturning circulation whose vertical extent is determined by the sill depth of the Falkland Plateau. The densest water masses formed in the southern Angola Basin and potentially reached the deep Cape Basin as Walvis Ridge Overflow Water. Palaeogeographic uncertainties are as important as the lack of precise knowledge of atmospheric CO2 levels for the simulated temperature and salinity spread in large parts of the South Atlantic. Overall temperature uncertainties reach up to 15 °C and increase significantly with water depth. The ensemble approach reveals temporal changes in the relative importance of geographic and radiative forcings for the simulated oceanographic conditions and, importantly, nonlinear interactions between them. The progressive northward opening of the highly restricted Angola Basin increased the sensitivity of local overturning and upper-ocean stratification to atmospheric CO2 concentrations due to large-scale changes in the hydrological cycle, while the chosen proto-Drake Passage depth is critical for the ocean dynamics and CO2 response in the southern South Atlantic. Finally, the simulated processes are integrated into a recent carbon burial framework to document the principal control of the regional gateway evolution on the progressive shift from the prevailing saline and oxygen-depleted subtropical water masses to the dominance of ventilated high-latitude deep waters.

Cuticular analysis of Late Pleistocene, Middle Holocene, and modern Nothofagus dombeyi leaves from Chile: Implications for understanding changes in plant function at different atmospheric CO2 concentrations

How will forests respond to increases in atmospheric CO2 concentrations over the next century? This question is the subject of intensive research, and is based mostly on the results of greenhouse experiments, landscape-level experiments and modeling. In this paper, we examined leaf morphological and physiological characteristics of Nothofagus dombeyi populations exposed to different atmospheric CO2 levels by analyzing leaf cuticle from a Late Pleistocene (∼15,500–13,200 cal yr BP) fossil site, a Middle Holocene (∼6700–4900 cal yr BP) fossil site, and a modern (2016) collection in mid-latitude Chile. Atmospheric CO2 concentrations were inferred as ∼230 ppm, ∼270 ppm and ∼ 400 ppm based on a comparison with icecore and instrumental records. Our findings show that as atmospheric CO2 concentrations increased by 74% during the transition from late glacial to modern conditions, stomatal density decreased by 24% and maximum stomatal conductance decreased by 42%. In contrast, we observed a 10% increase in stomatal size, a 195% increase in intrinsic water use efficiency, and an increase in leaf nitrogen content. Carbon discrimination decreased as CO2 levels increased contrary to our expectations underscoring that additional factors such as water availability and nutrients can affect carbon discrimination. We also tested the paleo-CO2 method of Franks that performed well under high CO2 conditions (∼400 ppm) but failed under low levels (∼230 ppm) of atmospheric CO2 indicating the need for a better understanding of photosynthesis during glacial times.

Plant-soil hydraulic interaction and rhizosphere bacterial community under biochar and CO2 enrichment

The increasing atmospheric CO2 concentration is a global concern that affects the plant-bacteria-soil system. Previous studies have investigated plant growth and bacteria activity under CO2 enrichment. However, the effects of coupled elevated CO2 and biochar amendment on the interactions of soil and medicinal plants are not well understood. This study aims to investigate the medicinal plant-soil hydraulic interactions and rhizosphere bacteria communities under coupled CO2 enrichment and biochar conditions. Two levels of CO2 concentration (400, 1000 ppm) and two biochar dosages (3%, 5% by mass) were considered. Pseudostellaria heterophylla was used as the tested medicinal plant. During plant growth, coupled CO2 enrichment and biochar at 3% and 5% dosage increased the volumetric water content at a matric suction of 33 kPa by 97% and 82% respectively, which indicates enhanced water retention. The transpiration rate of P. heterophylla was slightly reduced by 11–30% with an increase in biochar dosage due to higher total suction, while it was significantly reduced by up to 57% due to CO2 enrichment. In the rhizosphere of P. heterophylla, elevated CO2 (1000 ppm) coupled with 3% biochar dramatically increase the relative abundance of Thaumarchaeota, which played an important role in C and N cycles. Moreover, coupled CO2 enrichment and biochar addition resulted in the highest bacterial richness, while 3% biochar at ambient CO2 induced the highest bacterial diversity. This study provides a basis for understanding the medicinal plant-bacteria-soil system under CO2 enrichment and biochar conditions.

User-friendly carbon-cycle modelling and aspects of Phanerozoic climate change

Carbon-cycle modelling is essential for testing the main carbon sources and sinks as climate forcings, and we introduce and describe GEOCARB_NET, a graphical user interface for the geologic carbon and sulfur cycle model GEOCARBSULFvolc. The software system is menu-driven, user-friendly, and the user is never far removed from the basic input parameters from which atmospheric CO2 and O2 concentrations can be derived. GEOCARB_NET is supplied with several published models and the user can easily test and refine these models with different parametrizations. GEOCARB_NET also contains libraries of models and proxy data, which easily can be compared with each other. Our examples focus on how to use GEOCARB_NET in the context of Phanerozoic climate change and highlights how certain key input parameters can seriously affect reconstructed CO2 levels.

Increased ecological land and atmospheric CO2 dominate the growth of ecosystem carbon sinks under the regulation of environmental conditions in national key ecological function zones in China

Increased ecological land (IEL) such as forests and grasslands can greatly enhance ecosystem carbon sinks. Understanding the mechanisms for the magnitude of IEL-induced ecosystem carbon sinks is crucial for achieving carbon neutrality. We estimated the impact of IEL, specifically the increase in forests and grasslands, as well as global changes including atmospheric CO2 concentration, nitrogen deposition, and climate change on net ecosystem productivity (NEP) in National Key Ecological Function Zones (NKEFZs) in China using a calibrated ecological process model. The NEP in NKEFZs in China was calculated to be 119.4 Tg C yr−1, showing an increase of 42.6 Tg C yr−1 from 2001 to 2021. Compared to the slight contributions of climate change (−8.0%), nitrogen deposition (11.5%), and reduction in ecological land (−3.5%), the increase in NEP was primarily attributed to CO2 (66.5%) and IEL (33.5%). Moreover, the effect of IEL (14.8 Tg C yr−1) surpassed that of global change (13.1 Tg C yr−1) in the land use change zone. The IEL-induced NEP is significantly associated with CO2 fertilization, regulated by precipitation and nitrogen deposition. The high values of IEL-induced NEP occurred in areas with precipitation exceeding 800 mm and nitrogen deposition exceeding 25 kg N ha−1 yr−1. We recommend prioritizing the expansion of ecological land in areas with sufficient water and nutrients to enhance CO2 fertilization, while avoiding increasing ecological land in regions facing unfavorable climate change conditions. This study serves as a foundation for comprehending the NEP response to ecological restoration and global change.

Potential of 14C-based vs. ΔCO-based ΔffCO2 observations to estimate urban fossil fuel CO2 (ffCO2) emissions

Abstract. Atmospheric transport inversions are a powerful tool for independently estimating surface CO2 fluxes from atmospheric CO2 concentration measurements. However, additional tracers are needed to separate the fossil fuel CO2 (ffCO2) emissions from non-fossil CO2 fluxes. In this study, we focus on radiocarbon (14C), the most direct tracer of ffCO2, and the continuously measured surrogate tracer carbon monoxide (CO), which is co-emitted with ffCO2 during incomplete combustion. In the companion paper by Maier et al. (2024), we determined discrete 14C-based and continuous ΔCO-based estimates of the ffCO2 excess concentration (ΔffCO2) compared with a clean-air reference for the urban Heidelberg observation site in southwestern Germany. The ΔCO-based ΔffCO2 concentration was calculated by dividing the continuously measured ΔCO excess concentration by an average 14C-basedΔCO/ΔffCO2 ratio. Here, we use the CarboScope inversion framework adapted for the urban domain around Heidelberg to assess the potential of both types of ΔffCO2 observations to investigate ffCO2 emissions and their seasonal cycle. We find that, although they are more precise, 14C-based ΔffCO2 observations from almost 100 afternoon flask samples collected in the 2 years of 2019 and 2020 are not well suited for estimating robust ffCO2 emissions in the main footprint of this urban area, which has a very heterogeneous distribution of sources including several point sources. The benefit of the continuous ΔCO-based ΔffCO2 estimates is that they can be averaged to reduce the impact of individual hours with an inadequate model performance. We show that the weekly averaged ΔCO-based ΔffCO2 observations allow for a robust reconstruction of the seasonal cycle of the area source ffCO2 emissions from temporally flat a priori emissions. In particular, the distinct COVID-19 signal – with a steep drop in emissions in spring 2020 – is clearly present in these data-driven a posteriori results. Moreover, our top-down results show a shift in the seasonality of the area source ffCO2 emissions around Heidelberg in 2019 compared with the bottom-up estimates from the Netherlands Organization for Applied Scientific Research (TNO). This highlights the huge potential of ΔCO-based ΔffCO2 to validate bottom-up ffCO2 emissions at urban stations if the ΔCO/ΔffCO2 ratios can be determined without biases.

Prospective environmental burdens and benefits of fast-swing direct air carbon capture and storage

Direct air capture (DAC) in combination with storage of CO2 can lower atmospheric CO2 concentrations. This study investigates the environmental impact of a new fast-swing solid sorbent DAC system, including CO2 transport and storage, over its life cycle, using prospective life cycle assessment. This DAC technology is currently on technology readiness level 5 and is expected to operate on an industrial scale by 2030. The technology was upscaled to the industrial scale and future changes in the background over the lifetime of the system were included, such as electricity grid mix decarbonization. Environmental trade-offs for the new DAC system were assessed by comparing environmental benefits from CO2 sequestration with environmental burdens from production, operation and decommissioning. We considered three electricity generation configurations: grid-connected, wind-connected, and a hybrid configuration. We found net environmental benefits for all configurations and background scenarios for ecosystem damage and climate change. Net human health benefits were observed when the electricity grid decarbonizes quickly and without the use of a battery. The environmental benefits increase with decreasing electricity footprint and are comparable with other DAC technologies. This illustrates that the new DAC system can help to meet the climate goals.

Annual progress in global carbon capture, utilization, and storage in 2023

AbstractSince the industrial revolution, global anthropogenic CO2 emissions have surged dramatically to unsustainable levels, resulting in severe issues, such as global warming, extreme weather events, and species extinction. In response to this critical situation, extensive efforts have been undertaken across academia, industry, and policymaking sectors to deploy carbon capture, utilization, and storage (CCUS) technologies. Here, we present the annual summary of global CCUS for the year 2023. We begin by discussing the trends of anthropogenic CO2 emissions and atmospheric CO2 concentrations, and then offer an up‐to‐date summary of progress in academia, industry, and policy, respectively. In academia, we analyze the number and categories of publications and highlight some key breakthroughs. In the industry sector, we meticulously collect and present information on operational commercial carbon‐capture and storage facilities. Furthermore, we elucidate significant policy announcements and reforms across diverse regions. This concise and comprehensive annual report aims to inspire ongoing efforts and collaboration among academia, industry, and policymakers toward advancing carbon neutrality.

A missing link in the carbon cycle: phytoplankton light absorption under RCP emission scenarios

Abstract. Marine biota and biogeophysical mechanisms, such as phytoplankton light absorption, have attracted increasing attention in recent climate studies. Under global warming, the influence of phytoplankton on the climate system is expected to change. Previous studies analyzed the impact of phytoplankton light absorption under prescribed future atmospheric CO2 concentrations. However, the role of this biogeophysical mechanism under freely evolving atmospheric CO2 concentration and future CO2 emissions remains unknown. To shed light on this research gap, we perform simulations with the EcoGEnIE Earth system model (ESM) and prescribe CO2 emissions out to the year 2500 following the four Extended Concentration Pathway (ECP) scenarios, which for practical purposes we call Representative Concentration Pathway (RCP) scenarios. Under all RCP scenarios, our results indicate that phytoplankton light absorption leads to a shallower remineralization of organic matter and a reduced export efficiency, weakening the biological carbon pump. In contrast, this biogeophysical mechanism increases the surface chlorophyll by ∼ 2 %, the sea surface temperature (SST) by 0.2 to 0.6 °C, the atmospheric CO2 concentrations by 8 %–20 % and the atmospheric temperature by 0.3 to 0.9 °C. Under the RCP2.6, RCP4.5 and RCP6.0 scenarios, the magnitude of changes due to phytoplankton light absorption is similar. However, under the RCP8.5 scenario, the changes in the climate system are less pronounced due to decreasing ecosystem productivity as temperature increases, highlighting a reduced effect of phytoplankton light absorption under strong warming. Additionally, this work highlights the major role of phytoplankton light absorption on the climate system, suggesting highly uncertain feedbacks on the carbon cycle with uncertainties that may be in the range of those known from the land biota.

Rare earth elements as a tool to study the foliar nutrient uptake phenomenon under ambient and elevated atmospheric CO2 concentration

The ability of plants to uptake nutrients from mineral dust lying on their foliage may prove to be an important mechanism by which plants will cope with increasing CO2 levels in the atmosphere. This mechanism had only recently been reported and was shown to compensate for the projected dilution in plants ionome. However, this phenomenon has yet to be thoroughly studied, particularly in terms of the expected trends under different dust types and varying atmospheric CO2 concentrations, as projected by the IPCC. We treated plants grown under ambient (415 ppm) and elevated CO2 (850 ppm) conditions with either desert dust, volcanic ash, and fire ash analogues by applying it solely on plant foliage and studied their Rare Earth Elements concentrations and patterns. The Rare Earth Elements compositions of the treated plants originated from the dust application, and their incorporation into the plants led to a significant increase in plants vitality, evident in increased photosynthetic activity and biomass. Two trends in the foliar nutrient uptake mechanism were revealed by the Rare Earth Elements, one is that different treatments affected the plant in decreasing order volcanic ash > desert dust > fire ash. The second trend is that foliar intake becomes more significant under elevated CO2, an observation not previously seen. This testifies that the use of Rare Earth Elements in the study of foliar nutrient uptake, and other biological mechanisms is fundamental, and that foliar pathways of nutrient uptake will indeed become more dominant with increasing CO2 under expected atmospheric changes.

Concrete with Accelerated Naturally Carbonated Recycled Concrete Aggregates

Recycled concrete tends to be increasingly investigated with respect to the environmental needs, such as resource depletion, circularity and lack of landfill disposal spaces. A naturally accelerated carbonation procedure by using atmospheric CO2 concentration level and a cyclic wetting and drying of the recycled concrete aggregates was applied. A two stages carbonation process was applied. The recycled concretes exhibited similar mechanical properties of the reference concrete or even better durability as compared to the reference concrete prepared with natural rock aggregates. The carbonation of the outer layer of the recycled concrete aggregates was achieved with a simple method that can be widely applied and is sufficient to significantly increase the properties of the recycled concrete aggregates.

Leaf economics spectrum of wheat in response to multigenerational atmospheric elevated CO2

While numerous studies have explored the impacts of elevated atmospheric CO2 concentration (e[CO2]) on leaf traits in plants within a single life cycle, the effects of multigenerational e[CO2] on leaf functional traits and their interrelationships remain obscure in major crops. Leaf economics spectrum (LES) comprises a group of leaf traits, which describes trade-offs between the leaf characteristics that reflect carbon economy or returns on the investments of nutrients and dry mass. In this study, the wheat seeds harvested from a 7-generation experiment under the e[CO2] (800 μmol L−1) or the ambient CO2 concentration were planted to assess changes in the LES. Our results revealed a consistent increase in mass-normalized leaf nitrogen and phosphorus concentration under the e[CO2] over the generations. Photosynthetic phosphorus use efficiency was positively correlated with photosynthetic rate per unit mass, dark respiration per unit mass, photosynthetic rate per unit area, leaf phosphorus per unit area, and dark respiration per unit area. Moreover, we used structural equation model to illustrate the network of relationships among LES traits and shoot dry weight, providing insights into the effects of the multigenerational e[CO2] on wheat growth. This study contributes novel perspectives to our understandings of wheat responses to long-term climate change.

Soil organic carbon sequestration potential explained by mineralogical and microbiological activity using spectral transfer functions

The ability of soil to sequester carbon and reduce atmospheric CO2 concentrations is limited and depends on the soil minerals and their interaction with the microbiota. Microbial activities are closely associated with the types and amounts of soil organic matter (SOM) and clay minerals that have functional groups that interact with energy in Vis NIR-SWIR and Mid-IR wavelengths. The main objective of this research was to determine, based on these spectral ranges, the relation between mineralogical and organic compounds, as their sequestration and specialization in soils from Brazil. It was possible to map microbiological activity by spectral transfer functions and digital soil mapping reaching R2 from 0.77 to 0.85. Multiple regression equations were constructed to quantify enzymatic activity, microbial biomass carbon (MBC), particulate organic matter (POM), and resistant forms of carbon, and SOM associated with the mineral fraction (MAOM). All these properties were detected by specific bands obtained with the recursive feature elimination (RFE) algorithm, reaching correlations from 0.64 to 0.98 in specific ranges. The prediction model of the carbon sequestration potential was adjusted with microbiological and mineralogical variables from Vis-NIR-SWIR and the Mid-IR spectral range. A SARAR double autoregressive model was adjusted with r 0.61 and to a spatial error model (SEM) with r 0.7. The explanatory variables were associated with kaolinite, hematite, goethite, gibbsite, and the abundance of fungi, actinomycetes, vesico-arbuscular mycorrhizal fungi, enzymatic activity of beta-glucosidase, urease and phosphatase, and POM. Among the microbiological variables, the general abundance of fungi was the most important, in contrast to enzymatic activity that was the least important. The interaction between the different maps constructed and historical land use allowed the identification of areas that contribute to sequestering new carbon and could be the key to climate change mitigation strategies.

An Assessment of Changes in the Thermal Environment during the COVID-19 Lockdown: Case Studies from the Greenland and Norwegian Seas

The COVID-19 lockdown had a significant impact on human activities, reducing anthropogenic heat and CO2 emissions. To effectively assess the impact of the lockdown on the thermal environment, we used the sliding paired t-test, which we improved from the traditional sliding t-test by introducing the paired t-test for sliding statistical tests, to test the abrupt change in the thermal environment. Furthermore, an additive decomposition model and wavelet analysis method were used to analyze the characteristics of trend and irregular change, coherence, and phase difference of the time series data with respect to the thermal environment. We chose the Greenland Sea and the Norwegian Sea, regions highly sensitive to changes in climate and ocean circulation, as case studies and used remote sensing data of the sea surface temperature (SST) and the atmospheric CO2 concentration data obtained from the Goddard Earth Sciences Data and Information Services Center from January 2015 to December 2021 for the analysis. The results show that although the annual spatial mean SST in 2020 is lower than the mean of all 7 years in most areas of the two seas, there is no evidence of a significant mutation in the decrease in the SST during the lockdown in 2020 compared with the temperatures before, according to the sliding paired t-test. The analysis of the irregular components of the monthly mean SST decomposed by an additive decomposition model also does not show the anomalously low SST during the lockdown in 2020. In addition, the lockdown had almost no impact on the increasing trend of CO2 concentration. The wavelet analysis also shows that there is no obvious anomaly in coherence or phase difference between the periodic variation of the SST and the CO2 concentrations in 2020 compared with other years. These results suggest that the direct effect of the COVID-19 lockdown on the thermal environment of the study area could be negligible.