Mitigating climate disruption in time: A self-consistent approach for avoiding both near-term and long-term global warming

Global responses of wetland methane emissions to extreme temperature and precipitation

As global warming continues, events of extreme heat or heavy precipitation will become more frequent, while events of extreme cold will become less so. How wetlands around the globe will react to these extreme events is unclear yet critical, because they are among the greatest natural sources of methane(CH4). Here we use seven indices of extreme climate and the rate of methane emission from global wetlands(WME) during 2000-2019 simulated by 12 published models as input data. Our analyses suggest that extreme cold (particularly extreme low temperatures) inhibits WME, whereas extreme heat (particularly extreme high temperatures) accelerates WME. Our results also suggest that daily precipitation >10 mm accelerates WME, while much higher daily precipitation levels can slow WME. The correlation of extreme high temperature and precipitation with rate of WME became stronger during the study period, while the correlation between extreme low temperature and WME rate became weaker.

Direct Methane Removal from Air by Aerobic Methanotrophs

The rapid pace of climate change has created great urgency for short-term mitigation strategies. Appropriately, the long-term target for intervening in global warming is CO2, but experts suggest that methane should be a key short-term target. Methane has a warming impact 34 times greater than CO2 on a 100-year timescale, and 86 times greater on a 20-year timescale, and its short half-life in the atmosphere provides the opportunity for near-term positive climate impacts. One approach to removing methane is the use of bacteria for which methane is their sole carbon and energy source (methanotrophs). Such bacteria convert methane to CO2 and biomass, a potentially value-added product and co-benefit. If air above emissions sites with elevated methane is targeted, technology harnessing the aerobic methanotrophs has the potential to become economically viable and environmentally sound. This article discusses challenges and opportunities for using aerobic methanotrophs for methane removal from air, including the avoidance of increased N2O emissions.

N K. Using CRITIC-TOPSIS and python to examine the effect of 1-Hepatnol on the performance and emission characteristics of CRDI CI engine with split injection

Recently, biofuels with higher alcohol content have become a promising alternative to diesel fuel. These fuels are appealing because they are sustainable, renewable, and possess attractive fuel properties. This study uses a split injection strategy to analyze the performance and emissions of a CRDI diesel engine fueled by 1-heptanol. The work involved testing different fuel blends, ranging from 10 % to 30 %, while maintaining a constant engine speed of 1500 rpm and varying the operating load between 0 kg and 12 kg in 4 kg increments. During the second stage, the CRITIC-TOPSIS method determines the objective weights and rankings of various criteria and alternatives. A Python approach based on machine learning was used to ensure the CRITIC-TOPSIS results were accurate. Seven criteria were evaluated to maximize BTE while minimizing BSFC, NOx, smoke opacity, HC, CO, and CO2. The experimental results showed a slight drop of 2.98 % in BTE and an increase of about 13.33 % in BSFC. NOx and smoke opacity were reduced by 7.13%-4.53 %, while there was a 12.12 % increase in HC, 6.45 % higher CO, and a 5.5 % increase in CO2 at full load. Adding 1-heptanol to diesel and using a split injection strategy significantly reduced NOx and smoke opacity. The final ranking and best blend are determined using CRITIC-TOPSIS and Python algorithms to estimate performance and emissions criteria. At a load of 4 kg, D100 ranks first with a relative closeness value of 0.642, while at a pack of 8 kg, the blend HP20D80 ranks first with a relative closeness value of 0.633. According to the rankings, the HP20D80 blend is the best option for achieving optimal performance and reduced emissions in CRDI diesel engines. A research paper has presented a unique approach to multiple criteria decision-making (MCDM) validated using a Python algorithm. This method can assist decision-makers in making better-informed choices when faced with MCDM problems that involve various criteria and alternatives.

Microbial Catalysis for CO2 Sequestration: A Geobiological Approach

One of the greatest threats facing the planet is the continued increase in excess greenhouse gasses, with CO2 being the primary driver due to its rapid increase in only a century. Excess CO2 is exacerbating known climate tipping points that will have cascading local and global effects including loss of biodiversity, global warming, and climate migration. However, global reduction of CO2 emissions is not enough. Carbon dioxide removal (CDR) will also be needed to avoid the catastrophic effects of global warming. Although the drawdown and storage of CO2 occur naturally via the coupling of the silicate and carbonate cycles, they operate over geological timescales (thousands of years). Here, we suggest that microbes can be used to accelerate this process, perhaps by orders of magnitude, while simultaneously producing potentially valuable by-products. This could provide both a sustainable pathway for global drawdown of CO2 and an environmentally benign biosynthesis of materials. We discuss several different approaches, all of which involve enhancing the rate of silicate weathering. We use the silicate mineral olivine as a case study because of its favorable weathering properties, global abundance, and growing interest in CDR applications. Extensive research is needed to determine both the upper limit of the rate of silicate dissolution and its potential to economically scale to draw down significant amounts (Mt/Gt) of CO2 Other industrial processes have successfully cultivated microbial consortia to provide valuable services at scale (e.g., wastewater treatment, anaerobic digestion, fermentation), and we argue that similar economies of scale could be achieved from this research.

Development of Company-Specific Emission Factors with Confidence Intervals for Natural Gas Customer Meters in Southern California

Methane is both a significant and short-lived greenhouse gas compared to CO2, and reducing methane emissions from natural gas distribution systems may offer cost-effective reduction opportunities. We report substantial new direct leak rate measurements from customer meter set assemblies (MSAs) in Southern California. In a novel way, emission factors are defined in terms of aboveground Hazardous and Nonhazardous leak categories, which take direct advantage of readily available industry leak data. We also studied leaks that were not detected as part of normal leak survey procedures. As a result, this yields company-specific emission factors that can be used to track progress in reducing methane emissions. This approach also has the advantage of explicitly accounting for the skewed or fat-tail distribution of leak rates by treating high flow rate MSA leaks separately from low flow rate MSA leaks. The Southern California Gas (SoCalGas) methane emission factors, based on 485 leak rate measurements by direct enclosure, were 4.55 (95% confidence interval: 2.32 to 7.14) kg/day for Hazardous leaks, 0.149 (0.119 to 0.183) kg/day for Nonhazardous leaks, and 0.0039 (0.0003 to 0.0198) kg/day for Non-Detected leaks. The percentage of surveyed meters with nondetected leaks was 29.1% (24.3 to 34.6%). Based on a robust Monte Carlo analysis, total leak emissions from MSAs for the SoCalGas system were reduced by 35% based on data from 2015 to 2022. These reductions were attributed to surveying a larger number of MSAs and accelerated leak repair rates. In traditional population-based emission inventories, an individual emission factor for a given asset category is multiplied by the total population of MSAs within the category. This approach simply cannot capture the reduction in leak numbers and methane emissions resulting from leak mitigation and prevention programs.

A short climatology of black and brown carbon and their sources at a suburban site impacted by smoke in Brazil

Emissions from biomass burning challenge efforts to curb air pollution in cities downwind of fire-prone regions, as they contribute large amounts of brown carbon (BrC) and black carbon (BC) particles. We investigated the patterns of BrC and BC concentrations using Aethalometer data (at λ = 370 and 880 nm, respectively) spanning four years at a site impacted by the outflow of smoke. The data required to be post processed for the shadowing effect since, without correction, concentrations would be between 29% and 35% underestimated. The BrC concentrations were consistently higher than the BC concentrations, indicating the prevalence of aerosols from biomass burning. The results were supported by the Ångström coefficient (Å370/880), with values predominantly larger than 1 (mean ± standard deviation: 1.25 ± 0.31). Å370/880 values below 1 were more prevalent during the wet season, which suggests a contribution from fossil fuel combustion. We observed sharp BrC and BC seasonal signals, with mean minimum concentrations of 0.40 µg/m3 and 0.36 µg/m3, respectively, in the wet season, and mean maximum concentrations of 2.05 µg/m3 and 1.53 µg/m3 in the dry season. The largest concentrations were observed when northerly air masses moved over regions with a high density of fire spots. Local burning of residential solid waste and industrial combustion caused extreme BrC and BC concentrations under favourable wind directions. Although neither pollutant is included in any ambient air quality standards, our results suggest that transboundary smoke may hamper efforts to meet the World Health Organization guidelines for fine particles.

Scalable nano-architecture for stable near-blackbody solar absorption at high temperatures

Light trapping enhancement by nanostructures is ubiquitous in engineering applications, for example, in improving highly-efficient concentrating solar thermal (CST) technologies. However, most nano-engineered coatings and metasurfaces are not scalable to large surfaces ( > 100 m2) and are unstable at elevated temperatures ( > 850 °C), hindering their wide-spread adoption in CST. Here, we propose a scalable layer nano-architecture that can significantly enhance the solar absorption of an arbitrary material. Our electromagnetics modelling predicts that the absorptance of cutting-edge light-absorbers can be further enhanced by more than 70%, i.e. relative improvement towards blackbody absorption from a baseline value without the nano-architecture. Experimentally, the nano-architecture yields a solar absorber that is 35% optically closer to a blackbody, even after long-term (1000 h) high-temperature (900 °C) ageing in air. A stable solar absorptance of more than 97.88 ± 0.14% is achieved, to the best of our knowledge, the highest so far reported for these extreme ageing conditions. The scalability of the layer nano-architecture is further demonstrated with a drone-assisted deposition, paving the way towards a simple yet significant solar absorptance boosting and maintenance method for existing and newly developed CST absorbing materials.

Methane emission and influencing factors of China's oil and natural gas sector in 2020-2060: A source level analysis

The Chinese oil and gas industry requires targeted policies to reduce methane emissions. To achieve this goal, it is necessary to predict future methane emission trends and analyze the factors that influence them. However, changing economic development patterns, insufficient analysis of various factors influencing emissions, and inadequate resolution of methane emission inventories have made these goals difficult to achieve. Accordingly, this study aims to expand the methane emission estimation method to compile source-level emission inventories for future emissions, analyze the factors influencing them, and form a mechanistic understanding of the methane emissions from the local oil and gas industry. The research results indicate that methane emissions deriving from this industry will increase rapidly before 2030, after which they will decline slowly in all scenarios. The production and utilization processes in the natural gas supply chain, i.e., compressors and liquid unloading, include the main sources of methane emissions. Emissions are affected significantly by total production and consumption. Change in the overall supply and demand of natural gas affects change in methane emissions more significantly than adopting new technologies and strengthening facility maintenance, i.e., the overall supply and demand of natural gas are the dominant factors in controlling methane emissions. This study suggests that controlling the total demand for oil and gas should be at the core of the methane emission control policy for the local oil and gas industry. Moreover, equipment maintenance and emission reduction technologies should be used more effectively to reduce total emissions.

Improved scientific knowledge of methanogenesis and methanotrophy needed to slow climate change during the next 30 years

Owing to the high radiative forcing and short atmospheric residence time of methane, abatement of methane emissions offers a crucial opportunity for effective, rapid slowing of climate change. Here, we report on a colloquium jointly sponsored by the American Society for Microbiology and the American Geophysical Union, where 35 national and international experts from academia, the private sector, and government met to review understanding of the microbial processes of methanogenesis and methanotrophy. The colloquium addressed how advanced knowledge of the microbiology of methane production and consumption could inform waste management, including landfills and composts, and three areas of agricultural management: enteric emissions from ruminant livestock, manure management, and rice cultivation. Support for both basic and applied research in microbiology and its applications is urgently needed to accelerate the realization of the large potential for these near-term solutions to counteract climate change.

Enhancement of microalgal biomass productivity through mixotrophic culture process utilizing waste soy sauce and industrial flue gas

Wastewater treatment plants are indispensable facilities, which emit a massive amount of greenhouse gases. To boost CO₂ mitigation and wastewater treatment performance, mixotrophic microalgae cultivation using wastewater has recently been proposed. In this study, food industry wastewater (waste soy sauce) was applied to Chlorella sorokiniana UTEX 2714 cultivation. By using a medium with 20% (v/v) of 10-fold diluted soy sauce, the biomass and fatty acid methyl ester (FAME) productivity enhanced by 1.93 and 1.76 times, respectively. Biomass productivity increased up to 5.2 times when using medium with high soy sauce content under high-intensity light that inhibits cell growth in photoautotrophic environments. Furthermore, industrial flue gas treatment with wastewater was demonstrated by outdoor semi-continuous cultivation with 42% improved biomass production. Consequently, these results suggest that mixotrophic microalgal cultivation has great potential to address both climate change and water pollution while producing valuable products and can contribute to building a sustainable society.

Recent advances in constructed wetlands methane reduction: Mechanisms and methods

Constructed wetlands (CWs) are artificial systems that use natural processes to treat wastewater containing organic pollutants. This approach has been widely applied in both developing and developed countries worldwide, providing a cost-effective method for industrial wastewater treatment and the improvement of environmental water quality. However, due to the large organic carbon inputs, CWs is produced in varying amounts of CH4 and have the potential to become an important contributor to global climate change. Subsequently, research on the mitigation of CH4 emissions by CWs is key to achieving sustainable, low-carbon dependency wastewater treatment systems. This review evaluates the current research on CH4 emissions from CWs through bibliometric analysis, summarizing the reported mechanisms of CH4 generation, transfer and oxidation in CWs. Furthermore, the important environmental factors driving CH4 generation in CW systems are summarized, including: temperature, water table position, oxidation reduction potential, and the effects of CW characteristics such as wetland type, plant species composition, substrate type, CW-coupled microbial fuel cell, oxygen supply, available carbon source, and salinity. This review provides guidance and novel perspectives for sustainable and effective CW management, as well as for future studies on CH4 reduction in CWs.

Solar Driven Gas Phase Advanced Oxidation Processes for Methane Removal - Challenges and Perspectives

Methane (CH4 ) is a potent greenhouse gas and the second highest contributor to global warming. CH4 emissions are still growing at an alarmingly high pace. To limit global warming to 1.5 °C, one of the most effective strategies is to reduce rapidly the CH4 emissions by developing large-scale methane removal methods. The purpose of this perspective paper is threefold. (1) To highlight the technology gap dealing with low concentration CH4 (at many emission sources and in the atmosphere). (2) To analyze the challenges and prospects of solar-driven gas phase advanced oxidation processes for CH4 removal. And (3) to propose some ideas, which may help to develop solar-driven gas phase advanced oxidation processes and make them deployable at a climate significant scale.

Enabling Highly Enhanced Solar Thermoelectric Generator Efficiency by a CuCrMnCoAlN-Based Spectrally Selective Absorber

Harvesting solar energy to enhance thermoelectric generator efficiency is a highly effective strategy. However, it is a grand challenge but essential to increase solar-thermal conversion efficiency. A spectrally selective absorber, which is capable of boosting solar absorptance (α) while suppressing thermal emittance (ε), shows great potential to elevate the solar-thermal conversion efficiency. Herein, we fabricate a multilayer spectrally selective absorber with the assistance of high-entropy nitrides, which shows outstanding spectral selectivity (α/ε = 95.2/10.9%). Benefitting from the high-entropy nitrides, it is experimentally demonstrated that the as-deposited absorber exhibits superior thermal stability, which is crucial to ensure service life. Under 1000 W·m-2 simulated solar illumination, it achieves a very high surface temperature of 109.6 °C, making it suitable to enhance the efficiency of solar thermoelectric generators. Impressively, the integration of the proposed absorber with a commercial thermoelectric generator efficiently reinforces thermoelectric performance, offering a high output power of 1.99 mW. More importantly, by taking advantage of a thermal concentration strategy, it enables a further increase of the output power by 2.98 mW. This work provides a promising solar-thermal material to boost high thermoelectric performance and extends the application category of high-entropy nitrides.

Opportunities to tackle short-lived climate pollutants and other greenhouse gases for China

To limit the global temperature increase to below 1.5 °C, it is critical to reduce not only carbon dioxide (CO₂), but also specific non-CO₂ greenhouse gases (GHGs) and precursors, including some short-lived climate pollutants (SLCPs). These include emissions of black carbon, methane (CH4), tropospheric ozone, and fluorinated gases such as hydrofluorocarbons (HFCs). As the largest CH4 emitter and second-largest HFCs emitter, China plays a critical role in global efforts to reduce SLCPs and has acknowledged the need to reduce non-CO₂ GHGs in its 2060 carbon neutrality goal. This study reviewed leading international experiences with SLCP reduction to identify global best practices to inform target development and policy actions in China and elsewhere. We used bottom-up modeling and scenario analysis to evaluate pathways of non-CO₂ emission mitigation in China to 2050, drawing on mitigation measures developed through updated 2030 and 2050 cost curves. We identified a cost-effective reduction potential of 35 % for methane, 30 % for fluorinated gases, and 40 % for nitrous oxides-another potent GHG-in 2030 relative to 2015 levels for China under a Deep Non-CO₂ Mitigation scenario. Annual total reduction potential of 1080 million metric tons of CO₂ equivalent is also possible by 2030. For long-term targets, progress made on reducing SLCPs could help China reach its carbon neutrality target by 2060. While some uncertainties regarding the long-term mitigation potential of SLCPs remain, our analyses suggest that the fast adoption of available cost-effective technologies could allow China to reduce its non-CO₂ GHGs by 56 % by 2050.