non-CO2 Greenhouse Gases Research Articles (Page 1)

Bridging the Gap: A comprehensive review and cross-check analysis for China's Non-CO2 greenhouse gas emission estimates.

Previous projections from Earth system models have suggested that rising atmospheric CO2 concentrations would stimulate global vegetation production through the CO2 fertilization effect. Here we show that increased atmospheric dryness driven by climate warming will substantially counteract this effect. Using measurements from global eddy-covariance sites and a process-based model, we project that global vegetation gross primary production (GPP) will peak around the middle of the twenty-first century and subsequently decline. The peak of global GPP is projected to increase by only 5.4 ± 0.5% compared with the present. The stalled increase in GPP is more prominent in tropical regions. Additionally, the increased atmospheric dryness resulting from two non-CO2 greenhouse gases (CH4 and N2O) plays an important role in GPP changes. These gases induce climate warming and atmospheric dryness but, unlike CO2, lack a fertilization effect. This study underscores that climate warming-induced atmospheric dryness markedly reduces terrestrial vegetation production, potentially limiting the terrestrial carbon sink in the future.

Riverine and lake ecosystems are sources of global non-CO2 greenhouse gases (GHGs) and serve as sinks for pollutants, facing the dual challenges of mitigating GHG emissions and controlling water pollution. However, interactions between pollutant inputs and GHG emissions remain unclear. Herein, relying on a compiled data set of global non-CO2 GHGs and robust modeling, a watershed dissolved CH4 and N2O estimator is developed and validated on the global scale. Using the Dongting watershed (DTW) as a modeling example, various pollutant input scenarios were developed to explore the influence of changes in pollutant inputs on CO2-equivalent (CO2e) emissions from CH4 and N2O. Simulation results indicate that implementing pollutant inputs reduction measures in dissolved GHG hotspot areas will yield more efficient CO2e emission reduction benefits. Moreover, a critical paradox was revealed: while decreasing pollutant inputs leads to a sustained decline in direct CO2e (CO2eD) emissions, indirect CO2e (CO2eI) emissions from aquatic systems may show a minimal reduction in some cases. This paradox is closely tied to carbon-nitrogen ratio variations in aquatic system and can be well explained by carbon and nitrogen limitation principle, as defined by the Redfield ratio. Thus, our study suggests that cocontrol of carbon and nitrogen inputs within dissolved GHG hotspot areas is vital for achieving both water quality improvement and climate change mitigation simultaneously.

How can regional inequality caused by taxing non-CO2 greenhouse gases be mitigated? An economy-wide analysis.

The cost and benefit of synergistic emission reduction of CO2 and non-CO2 greenhouse gases in the industrial sector in the context of carbon neutrality

Assessment of methane and nitrous oxide emissions from urban community sewer networks: Field quantification and insights into environmental factors.

Commercial-scale co-composting of wood-derived biochar with source-selected organic fraction of municipal solid waste.

How reference scenario selection affects technical mitigation potential at the sub-national level: Evidence from China's agricultural non-CO2 greenhouse gas emissions

Livestock rearing as a key component of mitigation efforts for non-CO2 greenhouse gas emissions in global crop-livestock system

County-level Agricultural Non-CO2 Greenhouse Gas Emissions and Scenario Simulation in Hunan Province, China

Sewage treatment processes are considered an important source of greenhouse gas (GHG) emissions, particularly N2O and CH4. In rural sewage treatment processes, GHG emissions are often neglected owing to the small scale of treatment and dispersed distribution. In this study, the non-CO2 GHG emission quantity, spatiotemporal distribution characteristics, and influences factors were analyzed based on rural sewage from 2015 to 2020. Emissions from rural sewage treatment in 2020 reached 122.72 Gg (CO2-eq), comprising 69.81 Gg N2O and 52.91 Gg CH4, representing a 35.29% increase compared to 2015. There are large variations between province-level regions: more GHG was emitted from the eastern than the north-west of China. The treatment of rural domestic sewage can simultaneously purify water quality and decrease GHG emissions, and the improvement in the rate of treatment is beneficial to "carbon peak and carbon neutralization." GHG emissions from rural sewage treatment showed a positive correlation with both GDP and sewage discharge, and N2O was positively correlated with protein consumption per capita. This study would provide a theoretical basis for policy formulation, as it supplies basic data on carbon emissions for China's rural sewage treatment. SUMMARY: Rural sewage treatment (RST) plants contribute significantly to GHG emissions. N2O emission from rural sewage treatment in 2020 in China was 69.81 Gg. CH4 emission from rural sewage treatment in 2020 in China was 52.91 Gg. Large variations in GHG emissions were found between province-level regions. Domestic RST can simultaneously purify water quality and decrease GHG emissions.

Rodent-induced grassland degradation increases annual non-CO2 greenhouse gas fluxes and NO losses despite CH4 uptake enhancement

China has been experiencing rapidly growing agricultural non-CO2 greenhouse gas (GHG) emissions and aged population owing to its vast population and enormous food demands. However, the response of non-CO2 GHG emission to population aging-related food consumption is unclear. The food inspection survey reveals a significant difference in ruminant meat and staple food grain (typically rice) consumption between aged and young populations during the past decades. As a result, this dietary pattern in the aging population of 60+ reduce non-CO2 GHG emissions from 1.0 Tg CO2eq in 2005 to 10.1 Tg CO2eq in 2020 by one order of magnitude. By 2050, the net total non-CO2 GHG emissions from population aging-induced changes in food consumption will be further reduced by 34.5 Tg CO2eq under the shared socioeconomic pathways (SSPs), of which 86.8% is attributed to decreasing ruminant meat consumption (RMC), or 29.9 Tg CO2eq, accounting for 15.3% of total non-CO2 GHG emission from China’s RMC in 2050.

China's natural terrestrial ecosystems (NTEs) are significant sources and sinks of methane (CH₄) and nitrous oxide (N₂O), two potent non-CO₂ greenhouse gases. This article reviews CH₄ and N₂O inventories for China's NTEs, derived from site-specific extrapolation and models, to elucidate their spatiotemporal emission patterns. Despite progress, significant gaps remain, including large uncertainties due to model limitations and inconsistent driving data, insufficient assessments of integrated global warming potential (GWP) under long-term land-use and climate changes, the lack of freshwater emission inventories, and the need for more observations, refined prior sectoral contributions, and novel methods like isotopic signature applications in machine-learning and inversion techniques. This review offers a new perspective by compiling a new CH₄ and N₂O inventory and evaluating their integrated GWP for 1980-2020, developed using multi-model approaches to assess climate and land-use impacts. The review underscores the importance of CH₄ and N₂O sources and sinks, offering recommendations to enhance carbon sequestration and reduce emissions.

Agriculture emerges as a prominent contributor to CH4 and N2O emissions in China. However, estimates of these two non-CO2 greenhouse gases (GHGs) remain poorly constrained, hindering a precise understanding of their spatiotemporal dynamics and the development of effective mitigation strategies. Here, we established a consistent estimation framework that integrates emission-factor approach, data-driven models and process-based biogeochemical models, to identify the magnitudes, spatial variations, and long-term trends of agricultural non-CO2 GHG emissions in China's mainland from 1980 to 2023. Over the study period, the average total agricultural non-CO2 GHG emissions amounted to 722.5±102.3 Tg CO2-eq yr-1, with livestock CH4, cropland CH4, cropland N2O and livestock N2O contributing 41% (297.4±64.3 Tg CO2-eq yr-1), 31% (225.0±69.6 Tg CO2-eq yr-1), 18% (130.6±9.4 Tg CO2-eq yr-1) and 10% (69.4±20.2 Tg CO2-eq yr-1), respectively. Approximately 70% of these emissions were concentrated in the eastern region beyond the Hu Line, with emission hotspots identified in South-central China, East China, and the Sichuan Basin. Our analysis revealed three distinct temporal stages of total emissions during the study period: rapid growth (1980-late 1990s), slow growth (late 1990s-middle 2010s), and a stabilization stage (since the middle 2010s). These stages reflect the evolving trajectory of agriculture in China, from the expansion of agricultural yields, to the transformation of agricultural practices, and ultimately the pursuit of sustainable development. However, the temporal trajectory of emissions varied significantly across different regions, highlighting divergent levels of agricultural development. This study presents a comprehensive, gridded, and consistent estimate of agricultural non-CO2 GHG emissions in China, offering valuable insights for policymakers to develop tailored strategies that adapt to local conditions, enabling effective emission reduction measures.

Air pollution, global warming, and energy insecurity are three major problems facing the world. This study first examines whether 149 countries can transition 100% of their business-as-usual (BAU) all-sector energy to electricity and heat obtained from 100% wind-water-solar (WWS) sources to solve these problems. WWS eliminates energy-related air pollution deaths and CO2-equivalent emissions while reducing end-use energy needs by ∼54.4%, annual energy costs by ∼59.6%, and annual social (energy plus health plus climate) costs by ∼91.8% among nations, giving energy- and social-cost payback times of 5.9 and 0.78 years, respectively. Conversely, "all-of-the-above" policies promoting carbon capture (CC) and/or synthetic (as opposed to natural) direct air carbon capture (SDACC) to reduce or offset CO2 emissions trigger, with full penetration of CC/SDACC across 149 countries, $60-80 trillion/y in social cost, or 9.1-12.1 times the WWS social cost and only 1.1-25.6% lower social cost than BAU. Even when all CO2 is stored, CC and SDACC increase air pollution, CO2-equivalent emissions (due to capture inefficiencies and not capturing non-CO2 greenhouse gases), energy needs, and equipment costs relative to WWS. Sensitivity tests reinforce this finding. Although full penetration is extreme, any CC/SDACC level increases social cost and emissions substantially versus WWS. Thus, policies promoting CC and SDACC should be abandoned.

Anthropogenic emissions of non-CO2 greenhouse gases, such as low-concentration coal mine methane (cCH4 < 30 vol%), have a significant impact on global warming. The main component of coal mine methane is methane (CH4), which is both a greenhouse gas and a high-quality clean energy gas. To study the combustion and heat transfer reactions of low-concentration coal mine methane in a catalytic oxidation device, a numerical simulation approach was employed to establish a model of the catalytic oxidation device that includes periodic boundary conditions, methane combustion mechanisms, and turbulent-laminar flow characteristics. The core focus of this study is on the dynamic changes in the bed temperature of the oxidation device, the temperature of the extracted hot air, and the methane conversion rate. By varying parameters, the study explored the effects of factors such as methane concentration, switching time, and the amount of hot air extraction on the combustion efficiency and safety within the oxidation device. Furthermore, the optimal placement of the catalyst within the device was refined. The results indicate that the methane concentration in the oxidation device should not exceed 1.8 vol% to avoid equipment damage and potential safety risks due to excessively high methane concentrations. Under conditions where the methane concentration is between 1.6 and 1.8 vol%, the appropriate switching time is 30–60 s, and the amount of hot air extraction should be maintained within the range of 15–20% to achieve efficient combustion and heat transfer performance. Additionally, the placement of the catalyst needs to be finely adjusted according to the changes in the internal temperature field of the oxidation device to ensure the maximization of catalytic effects. This study not only provides theoretical basis and technical support for the efficient utilization of low-concentration coal mine methane (LC-CMM) but also offers references for its widespread promotion and application in the industrial field.

Growing contribution to radiative forcing from China's on-farm nitrous oxide emissions requires more attention.

Spatiotemporal characteristics and influencing factors of non-CO2 greenhouse gas emission intensity from China's livestock sector.

Reducing water input and promoting water productivity in rice field under alternate wetting and drying irrigation (AWD), instead of continuous flooding (CF), are vital due to increasing irrigation water scarcity. However, it is also important to understand how methane (CH4) and nitrous oxide (N2O) emissions and global warming potential ( of CH4 and N2O) respond to AWD under the influence of various factors. Here, we conducted a meta-analysis to investigate the impact of AWD on CH4 and N2O emissions and , and its modification by climate conditions, soil properties, and management practices. Overall, compared to CF, AWD significantly reduced CH4 emissions by 51.6% and by 46.9%, while increased N2O emissions by 44.0%. The effect of AWD on CH4 emissions was significantly modified by soil drying level, the number of drying events, mean annual precipitation (MAP), soil organic carbon content (SOC), growth cycle, and nitrogen fertilizer (N) application. Regarding N2O emissions, mean annual temperature (MAT), elevation, soil texture, and soil pH had significant impacts on the AWD effect. Consequently, the under AWD was altered by soil drying level, soil pH, and growth cycle. Additionally, we found that MAP or MAT can be used to accurately assess the changes of global or national CH4 and N2O emissions under mild AWD. Moreover, increasing SOC, but not N application, is a potential strategy to further reduce CH4 emissions under (mild) AWD, since no difference was found between application of 60-120 and > 120 kg N ha-1. Furthermore, the soil pH can serve as an indicator to assess the reduction of under (mild) AWD as indicated by a significant linear correlation between them. These findings can provide valuable data support for accurate evaluation of non-CO2 greenhouse gas emissions reduction in rice fields under large-scale promotion of AWD in the future.