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We studied the effects of long-term exposure (nine years) of birch (Betula papyrifera) trees to elevated CO(2) and/or O(3) on reproduction and seedling development at the Aspen FACE (Free-Air Carbon Dioxide Enrichment) site in Rhinelander, WI. We found that elevated CO(2) increased both the number of trees that flowered and the quantity of flowers (260% increase in male flower production), increased seed weight, germination rate, and seedling vigor. Elevated O(3) also increased flowering but decreased seed weight and germination rate. In the combination treatment (elevated CO(2)+O(3)) seed weight is decreased (20% reduction) while germination rate was unaffected. The evidence from this study indicates that elevated CO(2) may have a largely positive impact on forest tree reproduction and regeneration while elevated O(3) will likely have a negative impact.

We investigated the interactive effects of elevated concentrations of carbon dioxide ([CO(2)]) and ozone ([O(3)]) on radial growth, wood chemistry and structure of five 5-year-old trembling aspen (Populus tremuloides Michx.) clones and the wood chemistry of paper birch (Betula papyrifera Marsh.). Material for the study was collected from the Aspen FACE (free-air CO(2) enrichment) experiment in Rhinelander, WI, where the saplings had been exposed to four treatments: control, elevated [CO(2)] (560 ppm), elevated [O(3)] (1.5 x ambient) and their combination for five growing seasons. Wood properties of both species were altered in response to exposure to the treatments. In aspen, elevated [CO(2)] decreased uronic acids (constituents of, e.g., hemicellulose) and tended to increase stem diameter. In response to elevated [O(3)] exposure, acid-soluble lignin concentration decreased and vessel lumen diameter tended to decrease. Elevated [O(3)] increased the concentration of acetone-soluble extractives in paper birch, but tended to decrease the concentration of these compounds in aspen. In paper birch, elevated [CO(2)] decreased and elevated [O(3)] increased starch concentration. The responses of wood properties to 5 years of fumigation differed from those previously reported after 3 years of fumigation.

Atmospheric CO2 and tropospheric O3 are rising in many regions of the world. Little is known about how these two commonly co-occurring gases will affect reproductive fitness of important forest tree species. Here, we report on the long-term effects of CO2 and O3 for paper birch seedlings exposed for nearly their entire life history at the Aspen FACE (Free Air Carbon Dioxide Enrichment) site in Rhinelander, WI. Elevated CO2 increased both male and female flower production, while elevated O3 increased female flower production compared to trees in control rings. Interestingly, very little flowering has yet occurred in combined treatment. Elevated CO2 had significant positive effect on birch catkin size, weight, and germination success rate (elevated CO2 increased germination rate of birch by 110% compared to ambient CO2 concentrations, decreased seedling mortality by 73%, increased seed weight by 17%, increased root length by 59%, and root-to-shoot ratio was significantly decreased, all at 3 weeks after germination), while the opposite was true of elevated O3 (elevated O3 decreased the germination rate of birch by 62%, decreased seed weight by 25%, and increased root length by 15%). Under elevated CO2, plant dry mass increased by 9 and 78% at the end of 3 and 14 weeks, respectively. Also, the root and shoot lengths, as well as the biomass of the seedlings, were increased for seeds produced under elevated CO2, while the reverse was true for seedlings from seeds produced under the elevated O3. Similar trends in treatment differences were observed in seed characteristics, germination, and seedling development for seeds collected in both 2004 and 2005. Our results suggest that elevated CO2 and O3 can dramatically affect flowering, seed production, and seed quality of paper birch, affecting reproductive fitness of this species.

Human activities are increasing the concentrations of atmospheric carbon dioxide ([CO2]) and tropospheric ozone ([O3]), potentially leading to changes in the quantity and chemical quality of leaf litter inputs to forest soils. Because the quality and quantity of labile and recalcitrant carbon (C) compounds influence forest productivity through changes in soil organic matter content, characterizing changes in leaf litter in response to environmental change is critical to understanding the effects of global change on forests. We assessed the independent and combined effects of elevated [CO2] and elevated [O3] on foliar litter production and chemistry in aspen (Populus tremuloides Michx.) and birch-(Betula papyrifera Marsh.) aspen communities at the Aspen free-air CO2 enrichment (FACE) experiment in Rhinelander, WI. Litter was analyzed for concentrations of C, nitrogen (N), soluble sugars, lipids, lignin, cellulose, hemicellulose and C-based defensive compounds (soluble phenolics and condensed tannins). Concentrations of these chemical compounds in naturally senesced litter were similar in aspen and birch-aspen communities among treatments, except for N, the C:N ratio and lipids. Elevated [CO2] significantly increased C:N (+8.7%), lowered mean litter N concentration (-10.7%) but had no effect on the concentrations of soluble sugars, soluble phenolics and condensed tannins. Elevated [CO2] significantly increased litter biomass production (+33.3%), resulting in significant increases in fluxes of N, soluble sugars, soluble phenolics and condensed tannins to the soil. Elevated [O3] significantly increased litter concentrations of soluble sugars (+78.1%), soluble phenolics (+53.1%) and condensed tannins (+77.2%). There were no significant effects of elevated [CO2] or elevated [O3] on the concentrations of individual C structural carbohydrates (cellulose, hemicellulose and lignin). Elevated [CO2] significantly increased cellulose (+37.4%) input to soil, whereas elevated [O3] significantly reduced hemicellulose and lignin inputs to soil (-22.3 and -31.5%, respectively). The small changes in litter chemistry in response to elevated [CO2] and tropospheric [O3] that we observed, combined with changes in litter biomass production, could significantly alter the inputs of N, soluble sugars, condensed tannins, soluble phenolics, cellulose and lignin to forest soils in the future.

For the electro-reduction of CO 2 to syngas, the fabrication of electrodes with excellent and adjustable catalytic performance is a critical step. In this work, Ni particles encapsulated in N-doped carbon nanotubes on carbon paper (Ni@N-CNTs/CP) composites were designed and prepared via an in-situ chemical vapor deposition method. As confirmed by different characterization techniques, the Ni@N-CNTs are successfully synthesized, and the surface of the CP is evenly covered by the Ni@N-CNTs. The effects of Ni content and treating temperature on the textural properties of composites are carefully investigated. The Ni@N-CNTs/CP composites are directly employed as the electrode for electro-reduction of CO 2 , and the action mechanisms of the N species, Ni particles, and N-CNTs structure are explored as well. The electrode exhibits excellent catalytic activity and high stability, reaching a specific current of 10 mA cm−2. The H 2 /CO ratio in the achieved syngas can be tuned in the range of 5/1 to 1/1.5. Image 1 • A in-situ CVD method was employed to fabricate an electrode for electro-reduction of CO 2. • The as-synthesized Ni@N-CNTs evenly cover on the whole surface of CP. • The Ni@N-CNTs/CP electrode exhibits high CO 2 reduction activity and stability. • The ratio of H 2 /CO can be adjusted in the range of 5/1 to 1/1.5. • The action mechanism of different components are detailedly investigated. [ABSTRACT FROM AUTHOR]

Lime mud, a kind of industrial waste that produced in paper mill, was proposed as CO2 sorbent in calcium looping process. The carbonation performance of the lime mud was investigated in a dual‐fixed bed reactor (DFR) and a thermogravimetric analyzer (TGA). The carbonation kinetics of the lime mud in the chemical reaction controlled stage was analyzed by a surface reaction‐controlled kinetic model. The results show that the lime mud presents much poorer carbonation performance during the chemical reaction controlled stage compared with the limestone, mainly due to the high content of chlorine in the lime mud. A prewash treatment process was used to decrease the chlorine content to mitigate the sintering of the lime mud when calcined at high temperature. After prewash treatment, the prewashed lime mud shows much higher CO2 capture capacity during the chemical reaction controlled stage compared with the lime mud. A prolonged carbonation process successfully further enhances the microstructure and improves the carbonation performance of the prewashed lime mud in the chemical reaction controlled stage. The lime mud can be effectively used as CO2 sorbent in calcium looping process after prewash treatment and the following prolonged carbonation treatment. [ABSTRACT FROM AUTHOR]

Atmospheric chemical composition affects foliar chemical composition, which in turn influences the dynamics of both herbivory and decomposition in ecosystems. We assessed the independent and interactive effects of CO2 and O3 fumigation on foliar chemistry of quaking aspen (Populus tremuloides) and paper birch (Betula papyrifera) at a Free-Air CO2 Enrichment (FACE) facility in northern Wisconsin. Leaf samples were collected at five time periods during a single growing season, and analyzed for nitrogen. starch and condensed tannin concentrations, nitrogen resorption efficiencies (NREs), and C:N ratios. Enriched CO2 reduced foliar nitrogen concentrations in aspen and birch; O3 only marginally reduced nitrogen concentrations. NREs were unaffected by pollution treatment in aspen, declined with 03 exposure in birch, and this decline was ameliorated by enriched CO2. C:N ratios of abscised leaves increased in response to enriched CO2 in both tree species. O3 did not significantly alter C:N ratios in aspen, although values tended to be higher in + CO2 + O3 leaves. For birch, O3 decreased C:N ratios under ambient CO2 and increased C:N ratios under elevated CO2. Thus, under the combined pollutants, the C:N ratios of both aspen and birch leaves were elevated above the averaged responses to the individual and independent trace gas treatments. Starch concentrations were largely unresponsive to CO2 and O3 treatments in aspen. but increased in response to elevated CO2 in birch. Levels of condensed tannins were negligibly affected by CO2 and O3 treatments in aspen, but increased in response to enriched CO2 in birch. Results from this work suggest that changes in foliar chemical composition elicited by enriched CO2 are likely to impact herbivory and decomposition, whereas the effects of O3 are likely to be minor, except in cases where they influence plant response to CO2.

The objective of this study is to uncover the nature and strength of the effect that innovations have on CO 2 emissions. The main motivation of this research is to offer reliable and credible findings by eliminating some methodical and conceptual shortcomings of the existing papers. The scope of the analysis is examining the innovations-CO 2 emissions relationship in a sample of 43 countries in the period from 1991 to 2018. The research is based on the application of hidden panel cointegration theory and the concept of a partially asymmetric cointegration equation. The main findings of the study demonstrate that when innovations grow by 1%, the pattern of their change leads to an increase in CO 2 emissions by an average of 0.006%. At the same time, when innovations decline by 1%, their change leads to a reduction in CO 2 emissions by an average of 0.001%. Strictly speaking, in the phase of innovations growth, they have environmentally hostile average influence, while in the phase of innovations reduction, their impact is on average environmentally friendly. The average effect of innovations is very asymmetric, because negative environmental impact is about six times stronger than the positive one. Analysis by countries demonstrates that innovations influence varies significantly from country to country. The impact is environmentally friendly in only 32.6% of countries, regardless of whether innovations increase or decrease. In the remaining cases, the influence on the environment is hostile either when innovations grow, when they decline, or in both situations. The main conclusion of this study is that nature of the impact of innovations on CO 2 emissions is quite unfavorable, which points to the need for much greater support for green innovations., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The main hurdle in deploying renewable energy projects is the high initial cost, making it difficult for businesses and individuals to afford it. The fragility of the financial sector and human resource management further slows the pace of renewable energy demand. Therefore, we aim to investigate the impact of financial fragility and human resource management on renewable energy consumption over time horizon 1997-2020. To that end, the analysis employed the ARDL-PMG model. For Asia as a whole and all other sub-regions, including South East Asia, East Asia, South Asia, and Western Asia, the estimates for bank non-performing loans are notably negative. In general, these findings imply that a rise in financial fragility significantly reduces renewable energy consumption in the long run. In the short run, the estimates attached to both bank non-performing loans and bank costs are negatively significant in Asia and sub-regions of Western Asia only. The results for the human resources show that it exerts a significant and positive influence on renewable energy demand in Asia as a whole, South Asia, East Asia, and Western Asia. The estimates attached to human resources are statistically insignificant in all models in the short run. In the end, some important public strategies and their implementations have been discussed., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The study analyzes the impact of renewable energy investments (RENIV) on the environment in China. In doing so, the study uses sectoral carbon dioxide (CO 2 ) emissions as the environment indicator, considers RENIV as the explanatory variable, includes monthly data from 2004/1 to 2020/6, runs quantile on quantile regression approach as the fundamental model, and further performs quantile regression for the controlling. The study reveals that RENIV curb CO 2 emissions in all sectors at higher levels of sectoral CO 2 emissions. Also, RENIV have a varying impact based on quantiles and sectors. Moreover, the results are robust based on the alternative approach. Thus, RENIV have a significantly decreasing impact on sectoral CO 2 emissions in China. Accordingly, China policymakers should continue to focus on providing a decrease in energy and industrial sector CO 2 emissions as the highest emitting sectors., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The rapid development of the Internet has significantly impacted various socio-economic activities. Using Chinese Industrial Enterprise database and Industrial Enterprise Pollution database, this research examines the impact and mechanisms of Internet development on CO 2 emissions. The key findings are as follows: (1) Internet development has substantially reduced the CO 2 intensity of enterprises, and this conclusion remains robust even after performing a series of robustness analyses. (2) The major mechanisms responsible for the reduction in CO 2 emissions are productivity improvement, technological innovation, and energy structure adjustment. (3) The analysis of heterogeneity reveals that the effect of Internet development on CO 2 reduction is more pronounced in coastal areas, areas with a high share of secondary industry, low-carbon industries, clean industries, small-scale enterprises, and export enterprises. This study provides empirical evidence supporting China's "Internet+" strategy and its progress towards achieving the "Carbon Peaking and Carbon Neutrality Goals.", (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The BRICS nations-Brazil, Russia, India, China, and South Africa-have grown significantly in importance over the past few decades, playing a vital role in the development and growth of the global economy. This expansion has not been without cost, either, since these countries' concern over environmental deterioration has risen sharply. Both researchers and decision-makers have focused a lot of attention on the connection between economic growth and ecological sustainability. By using nonlinear autoregressive distributed lag (NARDL) approach, the complex relationships were analyzed between important economic indicators-such as gross domestic product (GDP), ecological innovations (EI), energy consumption (ENC), institutional performance (IP), and trade openness (TOP)-and their effect on carbon emissions and nitrous oxide emissions in the BRICS countries from 1990 to 2021, this study seeks to contribute to this important dialog. Principal component analysis is formed for technological innovations and institutional performance using six (ICT service exports as a percentage of service exports, computer communications as a percentage of commercial service exports, fixed telephone subscriptions per 100 people, internet users as a percentage of the population, number of patent applications, and R&D expenditures as a percentage of GDP) and twelve (government stability, investment profile, socioeconomic conditions, internal conflict, external conflict, military in politics, control of corruption, religious tensions, ethnic tensions, law and order, bureaucracy quality, and democratic accountability) distinct indicators, respectively. The results of nonlinear autoregressive distributed lag estimation show that increase in economic growth would increase carbon dioxide and nitrous oxide emissions. The positive and negative shocks in trade openness have positive and significant impact on carbon dioxide and nitrous oxide emissions in BRICS countries. Furthermore, the positive shock energy consumptions have positive and significant effect on Brazil and India when carbon dioxide and nitrous oxide emissions are used. However, EKC exists in BRICS countries when carbon dioxide and nitrous oxide emissions are used. According to long-term estimation, energy consumption and technological innovations in the BRICS countries show a strong and adverse link with nitrous oxide and a favorable relationship with carbon dioxide emissions. In the long run, environmental indicators are seen to have a major and unfavorable impact in BRICS nations. Finally, it is proposed that BRICS nations can assure environmental sustainability if they support creative activities, enhance their institutions, and support free trade policies., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The Middle East and North African (MENA) economies experienced substantial economic fluctuations due to variations in carbon emissions and energy use. For this purpose, the present study examines the factors influencing carbon emissions in MENA economies, particularly economic growth and energy use. To this end, this study disaggregates economic growth into three sectors (agriculture, industry, and services) and energy use into renewable and non-renewable, and examines their environmental impacts by including the roles of urbanization and trade openness in the environment Kuznets curve (EKC) framework. This study uses panel data from 16 MENA countries over the period 1990-2018 to estimate the short-run and long-run coefficients and the Granger causality between the variables. The empirical results using the Mean Augmented Group (AMG) and the Common Correlated Effects Mean Group (CCE-MG) revealed that (i) the signs of GDP per capita and its squared scores validate the EKC hypothesis only at the aggregate level; (ii) the coefficients of sectoral GDP show that the industry and services sectors have the highest contributions to carbon emissions in the MENA region; (iii) non-renewable energy increases emissions, whereas renewable energy lessens them. The outcomes of the Granger causality confirm (i) a bidirectional relationship between emissions and per capita GDP as well as sectoral GDP, between CO 2 emissions and renewable energy, and between per capita GDP and renewable and non-renewable energy however; (ii) a unidirectional causal impact running from non-renewable energy to CO 2 emissions is found in the short term. The study calls for effective policies to focus on curbing emissions in secondary and tertiary economic sectors by growing the part of renewable energy in the total energy mix., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

In the framework of an environmental Kuznets curve, the linkage between shadow economy and carbon dioxide (CO 2 ) emissions was evaluated for 145 countries from 1991 to 2017. In assessing the effect of the shadow economy on CO 2 emissions, we used panel quantile regression, panel fixed effects, and panel smooth transition regression as estimation methods. In addition, to deal with parameter heterogeneity, we resorted to the procedure of Lin and Ng (2012). We found two country groups that share homogeneous parameters. No environmental Kuznets curve was found for the set of all countries. Nevertheless, one was found for each of the homogeneous parameter country groups. This result supports different turning points for different groups of countries. Shadow economy contributed to reducing CO 2 emissions in group 1 and aggravated it in group 2. Manufacturing was revealed to be statistically significant for the countries of group 1. Fossil fuel rents increased the CO 2 emissions, mainly in group 2. Urbanization contributed to the hike of CO 2 emissions in both country groups but much more intensely for group 1. Evidence of a tendency for decreasing CO2 emissions was also found, reflecting the efficiency gains over time., (© 2023. The Author(s).)

The relationship between economic growth and environmental pollution continues to attract significant research interest for researchers, practitioners, and policymakers all over the globe. Theoretically, the environmental benefit of economic growth should be greater than its negative externality with higher level of development. However, from the African perspective, countries with higher economic performances often face several environmental challenges, which raises the doubt whether economic growth helps or constrains environmental quality improvement. Under the environmental Kuznets curve (EKC) hypothesis, this study re-examined the effect of economic growth on CO2 emissions conditional on the dynamics of urbanization, renewable energy, and good governance across 47 African countries using panel data from 1996 to 2019. We employ panel cointegration tests to establish whether there is a long-run equilibrium relationship among our variables. We also apply pooled mean group ARDL (PMG-ARDL) techniques and the Dumitrescu-Hurlin causality test to determine the long- and short-run effects of economic growth, urbanization, renewable energy consumption, and good governance on CO2 emissions. The results from the PMG estimator validate the EKC hypothesis since a 1% surge in GDP per capita increases emissions by 0.61% in the long run, while a 1% increase in its square decreases emissions by 0.03%. In the short-run, economic growth does not exercise any significant effect on emissions. Furthermore, results indicate a significantly negative and positive long-run effect of renewable energy and governance, respectively. Finally, our causality test shows bidirectional relationship between CO2 emissions and all the explanatory variables. Henceforth, we provided policy implications based on the study's results., (© 2023. The Author(s).)

The focus of sustainable development goals (SDGs) is to promote the use of renewable energy so that countries can achieve better environmental quality. However, the progression is plodding, and still, 80% of energy comes mainly from conventional sources in developing countries. The implementation of procedures depends on the political attitudes, political stability, and quality of institutions. India has a diverse political structure ranging from central government to state government to local governments. In the late '80 s, India witnessed a stiff rise in regional and national political parties, which leads more political competition. This paper tries to explain the possible relationship between political competition and CO 2 emission in India. With the application of the time series non-linear ARDL (NARDL) model, this study tries to find the asymmetric relationship between political competition and CO 2 emission. In our empirical model, we also include other important elements of environmental quality like innovation and fossil fuel consumption. Empirical results show that political competition is asymmetrically related to CO 2 emissions in the long run. Fossil fuel consumption and innovation also have a significant relationship with emissions. Based on the results, a few policy recommendations have been discussed., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Growing consumption is both necessary to end extreme poverty 1 and one of the main drivers of greenhouse gas emissions 2 , creating a potential tension between alleviating poverty and limiting global warming. Most poverty reduction has historically occurred because of economic growth 3-6 , which means that reducing poverty entails increasing not only the consumption of people living in poverty but also the consumption of people with a higher income. Here we estimate the emissions associated with the economic growth needed to alleviate extreme poverty using the international poverty line of US $2.15 per day (ref.  7 ). Even with historical energy- and carbon-intensity patterns, the global emissions increase associated with alleviating extreme poverty is modest, at 2.37 gigatonnes of carbon dioxide equivalent per year or 4.9% of 2019 global emissions. Lower inequality, higher energy efficiency and decarbonization of energy can ease this tension further: assuming the best historical performance, the emissions for poverty alleviation in 2050 will be reduced by 90%. More ambitious poverty lines require more economic growth in more countries, which leads to notably higher emissions. The challenge to align the development and climate objectives of the world is not in reconciling extreme poverty alleviation with climate objectives but in providing sustainable middle-income standards of living., (© 2023. The World Bank.)

Since the 1980s, Turkey has experienced a significant increase in both foreign direct investment (FDI) and its ecological footprint (EFP). While FDI is widely acknowledged as a pivotal driver of economic growth, its impact on environmental degradation is multifaceted and debated. Moreover, a country's institutional framework plays a key role in shaping this relationship. Yet, the influence of institutional structures on the FDI-environment nexus is often neglected in current literature. In this study, we investigate the environmental implications of FDI in Turkey from 1984 to 2018, employing time series analysis with a Fourier extension and accounting for institutional quality. Fourier function models give more effective results in modeling structural breaks. We first use Fourier techniques to assess the unit root and cointegration relationship. Upon establishing cointegration, we employ the DOLS estimator, extended with Fourier terms, to determine the long-term coefficients. We then assess the causal relationship between the variables using the Fourier causality test. Our findings indicate that while FDI exacerbates environmental degradation (supporting the pollution haven hypothesis), the interaction term of FDI-institutional quality mitigates this degradation (supporting the pollution halo hypothesis). Given these empirical findings, this study suggests that strengthening Turkey's institutional quality has the potential to amplify the environmental advantages of FDI, alongside its economic benefits., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Due to urbanization's substantial impact on economic development and environmental quality, particularly in emerging nations, the subject has attracted major attention in recent years. Urbanization increases infrastructure, transportation, and high energy consumption demand, leading to increased environmental degradation. Therefore, this study examines how urbanization has affected environmental degradation in Pakistan using yearly data from 1970 to 2020. A non-linear autoregressive distributed lag (NARDL) model is applied to study the asymmetric impact of urbanization on ecological footprint per capita. The results show that urbanization is asymmetrically associated with environmental degradation. Positive changes in urbanization led to increased environmental degradation, while negative changes in urbanization led to a decline in environmental degradation in Pakistan. Foreign direct investment and industrial production are positive and significant factors of environmental degradation, while trade openness and money supply are negatively linked with environmental degradation in Pakistan. Economic growth shows a positive link, while economic growth square shows a negative link with environmental degradation. These findings also confirm the environmental Kuznets curve (EKC) hypothesis in Pakistan. It is suggested that the urbanization threshold should be analyzed to determine where environmental degradation tends to decline, and less polluting technology and renewable energy resources should be encouraged to reduce environmental degradation in Pakistan., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This paper aims to analyze the link between environmental degradation and institutional quality and the price of oil moderated by economic complexity and the underground economy. We use quantile regressions with annual panel data for 15 countries in the Middle East and North Africa during 1995-2021. The findings indicate that institutional quality, economic complexity, and output positively and heterogeneously impact environmental degradation. However, the square of production has a negative impact, confirming an inverted U relationship between production and environmental degradation. Likewise, we find that the price of oil and the underground economy have a negative and heterogeneous impact on environmental degradation. Based on our results, a potential recommendation for policymakers is that the institutional framework of Middle Eastern and North African countries should be accompanied by a more significant concern for the environment instead of prioritizing extractive growth that is detrimental to the environment's environmental sustainability. Likewise, economic diversification will mitigate environmental degradation and improve formal employment. Our findings are relevant to policymakers and researchers interested in promoting ecological sustainability., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This study investigates a modified version of the Okun's Law that incorporates energy consumption and temperature for five Central Asian countries, while it employs the ARDL methodology, spanning the period 1995-2018. While the original Okun's Law is not supported, the analysis does find support for the modified Law, suggesting the importance of regional specific factors. The results document the presence of a negative association between unemployment and real GNP both in the short and in the long run. The impact of energy consumption on unemployment is positive in the long run, while the temperature impacts unemployment both in the short and in the long run., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This paper investigates the impact of geopolitical risks on renewable energy generation in MENAT oil-importing countries, namely, Egypt, Tunisia, and Turkey over the period 1990-2020 using the autoregressive distributed lag (ARDL) model. The main findings emphasize that geopolitical risks play a crucial role in inducing renewable energy development in MENAT oil-importing countries in the short and long run. Financial development appears to positively and significantly affect renewable energy generation in the three countries. Furthermore, the speeds of adjustment towards the long-run equilibrium are 36.78%, 66.03%, and 17.81% annually in Egypt, Tunisia, and Turkey, respectively. In today's volatile and turbulent world, dramatically rising geopolitical risks make the transition to renewable energy an inevitable reality. Consequently, it is incumbent upon policymakers and relevant authorities in MENAT oil-importing countries to preemptively redirect their efforts and strategies to conform to the demands of the inevitable transition to renewable energy sources and boost energy self-reliance., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The industrial revolution has dramatically altered the environment and ecosystem. So many scholars have empirically attempted to reveal the most influential anthropogenic factors on environmental degradation. For this purpose, this study examines the leading determinants of CO 2 emissions in the context of economic policy uncertainty (EPU) for 14 developed countries within the framework of the extended stochastic impacts by regression on population, affluence and technology (STIRPAT) environmental model from 1997-2018. For empirical modeling, CO 2 emission is treated as the dependent variable, which is a strong proxy for environmental degradation. In addition to the GDP per capita, population density, and energy intensity (a proxy for technology), the basic model is extended to include variables such as EPU, renewable energy, trade openness, globalization, and information and communications technology (ICT) index. While the estimation results by the dynamic conditional correlation (DCC) estimator, which are also supported by robustness analysis, suggest that GDP per capita and energy intensity are the main contributors to emission levels, population density has no significant impact on CO 2 . Furthermore, while renewable energy (in model 2), trade openness (in model 4), and globalization (in model 6) have negative impacts on CO 2 emission, technology (in models 5 and 6) and EPU (in model 6) make marginal contributions to CO 2 ., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Climate change is altering ecological systems and poses a serious threat to human life. Climate change also seriously influences on livestock production by interfering with growth, reproduction, and production. Livestock, on the other hand, is blamed for being a significant contributor to climate change, emitting 8.1 gigatonnes of CO2-eq per year and accounting for two-thirds of global ammonia emissions. Methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) are three major greenhouse gases (GHG) that are primarily produced by enteric fermentation, feed production, diet management, and total product output. Ruminants account for three-quarters of total CO2-equivalent (CO2-eq) emissions from the livestock sector. The global dairy sector alone emits 4.0% of global anthropogenic GHG emissions. Hence, dairy farming needs to engage in environmental impact assessment. Public concern for a sustainable and environmentally friendly farming system is growing, resulting in the significant importance of food-based life cycle assessment (LCA). Over the last decade, LCA has been used in agriculture to assess total GHG emissions associated with products such as milk and manure. It includes the production of farm inputs, farm emissions, milk processing, transportation, consumer use, and waste. LCA studies on milk production would assist us in identifying the specific production processes/areas that contribute to excessive greenhouse gas emissions when producing milk and recommending appropriate mitigation strategies to be implemented for a clean, green, and resilient environment., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

Russia holds the position of being the third largest global producer of oil and plays a significant role in the supply of oil and gas to Europe. The ongoing war conflict has the potential to impede the bilateral and multilateral relations between Russia and Europe. The ramifications of this event will have notable reverberations for environmental endeavors in Europe. The aforementioned premise forms the basis of our investigation, wherein we scrutinize the correlation among oil price, coal price, gas price, economic growth, and coal consumption, while taking into account the ramifications of the Russian-Ukrainian conflict. We adopted fully "modified ordinary least square (FMOLS), dynamic ordinary least square (DOLS), and canonical cointegration regression (CCR)" econometric techniques to gauge the nexus between factors of interest in the top 4 European Russian gas importer economies (Poland, Netherland, Hungry, and Germany). The empirical outcomes reveal substantial negative impact of economic growth and coal price elasticity on the coal consumption. On the contrary, oil and gas price elasticities depict significant positive influence on the coal consumption. Hence, this study concludes that a rise in oil and gas prices leads to an increase in coal consumption, which in turn negatively impacts environmental quality. Furthermore, the occurrence of war has the potential to impede the utilization of coal resources in Netherlands and Hungary. On the other hand, the impact of war is noteworthy and constructive in Poland and Germany. Thus, war results ecological imbalance in Poland and Germany in particular. Governments, decision-makers, stakeholders, and environmentalists must develop a long-term plan that calls for a paradigm shift away from gas, oil, and coal usage and toward more environmentally benign renewable energy sources., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

We examined the relationship of carbon dioxide (CO 2 ) emissions with real per capita GDP and energy consumption in the ASEAN region using panel data from 1960 to 2021. We employed various panel unit root tests (IPS, Fisher-ADF, Fisher-PP) and panel cointegration tests (Kao and Pedroni). We find robust empirical evidence supporting the validity of the Environmental Kuznets Curve hypothesis, suggesting the existence of a per capita income turning point (approximately USD 4,808.85) where CO 2 emissions and real income begin to decouple. This suggests the presence of an environmentally sustainable economic growth path beyond this threshold. The study highlights the importance of a reduction of fossil fuel use and the adoption of coordinated strategic plans among ASEAN member states to reduce carbon dioxide emissions., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This paper aims to revisit the interdependency between business conditions, climate policy change, and the environmental pollution of the USA. Interestingly, our paper represents a completion to the existing literature on three levels at least. First, we propose to analyze this issue during normal periods and periods of turmoil, particularly the COVID-19 outbreak. To do so, contrary to previous studies that used economic growth, we employ the ADS index as a real-time business conditions measurement. Second, we employ a frequency approach, based on the continuous wavelet transform, allowing us to understand the nature of the relationship. Understanding whether the relationship holds in the short- or long-term is useful for policymakers in monitoring public policies to achieve CO 2 emission reduction as well as to investors interested in high value-added projects. Our analysis shows that, during the last two decades, the relationship between business conditions as well as climate uncertainty index and CO 2 emissions is observed during the long- and short-term, and driven through economic conditions. However, during the crisis periods, the effect is detected across various scales and the relationship is bi-directional. Our results have several practical implications for the US policymakers to consider when setting policies for fighting pollution emissions and environmental protection., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Pollution and energy crisis are actual issues in Europe, including the EU Central and Eastern European states. In this context, the objective of this paper is to assess the impact of economic growth and electricity prices for non-household consumers on pollution. The empirical findings reveal the U pattern for energy industry and inverted U pattern for manufacturing in the period 2007-2021 in the EU countries from Central and Eastern Europe. Renewable energy consumption reduces the CO2 and GHG emissions in energy industry. FDI and electricity prices determine the reduction in GHG and CO2 emissions in both sectors. These results are the basis for policy recommendations., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The connection between ecological footprint and economic complexity has significant implications for environmental sustainability regarding the policy. Additionally, institutional quality is crucial in ensuring environmental sustainability and moderating the link between economic complexity and ecological footprint. The task of achieving sustainable environmental development and preventing further degradation of the environment poses a formidable challenge to policymakers. This study delves into the significance of technology innovation and renewable energy in creating a more sustainable environment. Recognizing the need for a more critical review, this research establishes the dynamic linkage between ecological footprint, renewable energy consumption, and technological innovation, especially in conjunction with a moderating component, particularly institutional quality, in G20 countries from 1990 to 2021. We employ advanced panel approaches to address panel data analysis concerns, such as cross-sectional dependence, slope heterogeneity, unit root, cointegration test and CS-ARDL. The long-term estimator indicates that renewable energy and technological innovation negatively but significantly impact the ecological footprint. Whilst economic growth, FDI, and urbanization have shown a positive and significant impact on ecological footprint; institutional quality negatively moderates the relationship between ecological footprint, renewable energy, and technological innovation in the G20 countries. Further evidence from the Dumitrescu-Hurlin Granger causality test shows that efforts to expand access to renewable energy, technological advancements, and economic growth will significantly affect environmental impacts. Based on our results, it is imperative to introduce more favorable legislation and encourage technological advancements in the field of renewable energy if we want to achieve our sustainable development objectives., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

China Overseas Economic and Trade Cooperation Zone (COCZs) which as a platform for China's foreign investment and trade has a potential impact on CO 2 emissions, while strengthening bilateral investment and trade between China and the host countries. Since most of the COCZs are located in countries along the "Belt and Road," the purpose of this paper is to investigate the impact of COCZs on CO 2 emissions of the countries along the "Belt and Road" and the mechanism of this impact. We constructed a panel data of 63 countries along the "Belt and Road" from 2000 to 2020, and conducted an empirical study using the difference-in-difference (DID) model. Our research result show that COCZs can significantly increase the CO 2 emissions of the countries along the "Belt and Road." Then, we conduct a series of robustness tests and endogeneity test on the estimation results of the baseline model, and the results of the tests all support the conclusion reached by the baseline model. Our heterogeneity analysis reveals that the effect of COCZs on CO 2 emissions is more significant in Asian countries with lower national income or industrialization and higher country risk. Finally, we analyzed industrial value added and energy depletion as possible impact mechanisms, the results of mechanism model shows that COCZs can increase the industrial value added and then significantly increase CO 2 emissions, but energy depletion was not an efficient mechanism. Our paper provides a new insight into the impact of bilateral economic and trade cooperation zones on CO 2 emissions in host countries., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

China has abundant agricultural and forestry waste resources that are crucial sources of energy for substituting fossil fuels and achieving the carbon peaking and carbon neutrality goals. These resources play an essential role in reducing carbon dioxide emissions and promoting sustainable development. This paper presents an estimation of the number of biomass resources that can be used for energy in 2020 by using parameters such as the grass-to-grain ratio coefficient and excretion coefficient. Moreover, the potential for conversion of biomass resources into biomass energy is evaluated by using parameters such as lower heating value and gas production coefficient. Finally, based on the whole life cycle theory, the potential of biomass energy utilization to reduce carbon dioxide emissions and its impact on carbon peaking is calculated. It was found that the total amount of fossil fuels that can be replaced by biomass energy is 256 million tons of standard coal. Utilizing biomass energy can reduce carbon dioxide emissions by approximately 520 million tons, with a peak impact of 4-6% on carbon peaking. The research results presented in this article can provide valuable data to support the promotion of green transformation in various regions. The findings can serve as a useful reference for formulating localized biomass utilization plans and designing effective emission reduction policies., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Extensive theoretical and empirical evidence supports the crucial role of savings in driving a nation's economic growth and development. However, previous studies have not considered their potential environmental implications. This study aims to explore the influence of savings and remittances on the Developing-8 countries (D-8) from 1989 to 2019, using the panel autoregressive distributed (ARDL) model. The findings reveal that national savings and remittances, in the long run, help mitigate environmental degradation in the D-8 countries but energy use and population growth stimulate carbon dioxide (CO 2 ) emissions. In contrast, economic growth does not significantly affect these countries' environmental quality in the long run. However, none of the explanatory variables have any significant relationship with CO 2 emissions in the short run. Therefore, policymakers in the D-8 countries are strongly encouraged to prioritize the enhancement of national savings across the three economic agents to maximize the positive effects of savings on environmental quality. Government savings can be increased by reducing deficits and borrowings, while corporate savings can be encouraged by implementing investment tax credits and promoting research and development. Additionally, governments can embark on public enlightenment campaigns on financial education and provide incentives to encourage household savings., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Zinc nanoparticles were electro-deposited along the fibres of carbon paper (CP) substrate uniformly in a salt-induced pre-phase separation region solution. The as-prepared Zn/CP electrode was used for electro-reduction of CO 2 and exhibited a Faradaic efficiency towards CO of 97.6% with a current density of 340 mA cm−2 in an H-type cell, which is the best result to date. [Display omitted] Efficient electrode design is crucial for the electrochemical reduction of CO 2 to produce valuable chemicals. The solution used for the preparation of electrodes can affect their overall properties, which in turn determine the reaction efficiency. In this work, we report that transition metal salts could induce the change of two-phase ionic liquid/ethanol mixture into miscible one phase. Pre-phase separation region near the phase boundary of the ternary system was observed. Zinc nanoparticles were electro-deposited along the fibres of carbon paper (CP) substrate uniformly in the salt-induced pre-phase separation region solution. The as-prepared Zn(1)/CP electrode exhibits super-wettability to the electrolyte, rendering very high catalytic performance for CO 2 electro-reduction, and the Faradaic efficiency towards CO is 97.6% with a current density of 340 mA cm −2, which is the best result to date in an H-type cell. [ABSTRACT FROM AUTHOR]

Premise: The Aptian-Albian (121.4-100.5 Ma) was a greenhouse period with global temperatures estimated as 10-15°C warmer than pre-industrial conditions, so it is surprising that the most reliable CO 2 estimates from this time are <1400 ppm. This low CO 2 during a warm period implies a very high Earth-system sensitivity in the range of 6 to 9°C per CO 2 doubling between the Aptian-Albian and today., Methods: We applied a well-vetted paleo-CO 2 proxy based on leaf gas-exchange principles (Franks model) to two Pseudotorellia species from three stratigraphically similar samples at the Tevshiin Govi lignite mine in central Mongolia (~119.7-100.5 Ma)., Results: Our median estimated CO 2 concentration from the three respective samples was 2132, 2405, and 2770 ppm. The primary reason for the high estimated CO 2 but with relatively large uncertainties is the very low stomatal density in both species, where small variations propagate to large changes in estimated CO 2 . Indeed, we found that at least 15 leaves are required before the aggregate estimated CO 2 approaches that of the full data set., Conclusions: Our three CO 2 estimates all exceeded 2000 ppm, translating to an Earth-system sensitivity (~3-5°C/CO 2 doubling) that is more in keeping with the current understanding of the long-term climate system. Because of our large sample size, the directly measured inputs did not contribute much to the overall uncertainty in estimated CO 2 ; instead, the inferred inputs were responsible for most of the overall uncertainty and thus should be scrutinized for their value choices., (© 2024 Botanical Society of America.)

This study examines the connection between economic policy uncertainty (EPU), CO2 emissions, and financial inclusion in developed and developing countries. Using the data from 2004 to 2021, advanced statistical techniques are employed, including Sobel test, to explore the mediating effect of financial inclusion on the relationship between economic policy uncertainty (EPU) and CO2 emissions. There is a dearth of research examining these three variables together in a single study. Similarly, using financial inclusion as a mediator in the relation of EPU and CO2 emissions is a novel concept. This article employs a multi-indicator approach to measure key variables like CO2 emissions and financial inclusion. The results indicate that uncertainties in economic policies contribute in practices that lead to higher CO2 emissions in overall panel data of 44 countries. In addition, when considering the relationship between EPU and FI, the results indicate a significant and negative relationship between EPU and FI. If there is uncertainty in economic policies, it may lead toward challenges and hurdles in financial inclusion. When the mediating affect was checked, it was found financial inclusion acts as a significant mediator in the relationship between EPU and CO2 emissions, depicting that financial inclusion fosters the environmental quality and mitigates the potential harmful effects of environmental aspects of economic policy uncertainty. Therefore, policies that promote financial inclusion should be given top priority by governments, particularly in emerging nations. Financial literacy and bank service accessibility should be promoted. These measures would lessen the impact of staggering economic policies on CO2 emissions. It is necessary for policymakers to include environmental factors, specifically those relating to carbon emissions, into economic strategies. This requires encouraging industries to adopt eco-friendly practices and coordinating economic strategies with sustainability objectives., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This study examines the nexus between "stock returns," carbon emissions, and "environmental tax" in 28 OECD countries for the period 1994 to 2014. To this end, we employ second-generation econometric techniques that are robust to macroeconomic and financial datasets to eliminate the issues associated with heterogeneity and cross-sectional dependence. The "common correlated effects mean group (CCEMG)" and "augmented mean group (AMG)" estimators are a pioneering attempt to explore the association between the cross sections. These approaches take into account the complexities of real-world data and provide a more accurate understanding of the relationship between the variables. Several studies explored the relationship between CO 2 emissions and economic growth. However, the literature lacks studies examining the impact of "environmental tax" implementation on "stock returns," which is a central policy instrument to curb emissions. The results demonstrate a significant and negative relationship between CO 2 emissions and "stock market index returns" and a positive and significant relationship between "environmental tax" and "stock market index returns." Furthermore, both these relationships prevail in the world's biggest financial markets and second largest CO 2 emitters, the USA. The empirical findings offer various useful implications for investors, policymakers, brokers, corporations, governmental pollution abatement institutions, and other stakeholders who wish to obtain a carbon risk premium., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The Belt and Road Initiative proposed by China has significantly increased trade in countries along the Belt and Road (B&R). Since most of these countries are developing and emerging economies, the pressure to reduce carbon emissions poses a leading challenge for them. Carbon productivity has become a key indicator for assessing the degree of low-carbon development, as it can link economic development with CO 2 emission reduction. However, few studies have investigated how international trade affects carbon productivity. Based on panel data from 43 countries along the B&R during 2001-2019, this paper uses a system GMM model to explore the impact of international trade on carbon productivity. Then, we divide the 43 countries in the sample into two groups according to their income levels to compare the different effects of international trade on carbon productivity. The results show that, first, the carbon productivity of the examined B&R countries has an overall increasing trend, and there is a significant heterogeneity of carbon productivity among countries with different income levels. Second, the effects of international trade, export, and import on carbon productivity are all significantly positive, and export's effect is higher than import. In the high-income group, carbon productivity is more likely to be improved by trade than in the middle (low)-income group. Third, economic development level, urbanization, and energy productivity are positively associated with carbon productivity, while CO 2 per capita and government size inhibit carbon productivity improvement. Insight into the impact of international trade on carbon productivity provides theoretical support for B&R countries to better leverage foreign trade activities to achieve a green economy., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: A critical parameter of extracorporeal CO 2 removal (ECCO 2 R) applications is the CO 2 removal rate (VCO 2 ). Low-flow venovenous extracorporeal support with large-size membrane lung remains undefined. This study aimed to evaluate the VCO 2 of a low-flow ECCO 2 R with large-size membrane lung using a renal replacement therapy platform in an experimental animal model., Methods: Twelve healthy pigs were placed under mechanical ventilation and connected to an ECCO 2 R-CRRT system (surface area = 1.8 m 2 ; OMNIset®, BBraun, Germany). Respiratory settings were reduced to induce two degrees of hypercapnia. VCO 2 was recorded under different combinations of PaCO 2 (50-69 or 70-89 mm Hg), extracorporeal blood flow (ECBF; 200 or 350 mL/min), and gas flow (4, 6, or 10 L/min)., Results: VCO 2 increased with ECBF at all three gas flow rates. In severe hypercapnia, the increase in sweep gas flow from 4 to 10 L/min increased VCO 2 from 86.38 ± 7.08 to 96.50 ± 8.71 mL/min at an ECBF of 350 mL/min, whereas at ECBF of 200 mL/min, any increase was less effective. But in mild hypercapnia, the increase in sweep gas flow result in significantly increased VCO 2 at two ECBF. VCO 2 increased with PaCO 2 from 50-69 to 70-89 mm Hg at an ECBF of 350 mL/min, but not at ECBF of 200 mL/min. Post-membrane lung PCO 2 levels were similar for different levels of premembrane lung PCO 2 (p = 0.08), highlighting the gas exchange diffusion efficacy of the membrane lung in gas exchange diffusion. In severe hypercapnia, the reduction of PaCO 2 elevated from 11.5% to 19.6% with ECBF increase only at a high gas flow of 10 L/min (p < 0.05) and increase of gas flow significantly reduced PaCO 2 only at a high ECBF of 350 mL/min (p < 0.05)., Conclusions: Low-flow venovenous extracorporeal ECCO 2 R-CRRT with large-size membrane lung is more efficient with the increase of ECBF, sweep gas flow rate, and the degree of hypercapnia. The influence of sweep gas flow on VCO 2 depends on the ECBF and degree of hypercapnia. Higher ECBF and gas flow should be chosen to reverse severe hypercapnia., (© 2024 The Authors. Artificial Organs published by International Center for Artificial Organ and Transplantation (ICAOT) and Wiley Periodicals LLC.)

A growing number of studies have examined the extent to which economic liberalization policies would influence carbon emissions. These studies have examined this relationship while neglecting the key role that renewable energy could play in this complex relationship. The study fills that gap. It aims to examine the mediated effect of renewable energy consumption in the relationship between economic freedom and carbon emissions in 138 countries worldwide over the period 1995-2018. In this perspective, the study followed a second-generation panel econometric tests. We used Driscoll and Kraay standard errors (DKSE) and common correlated effect mean group (CCEMG) estimators for baseline results. The robustness of the results was checked using fully modified ordinary least squares (FMOLS), system generalized method of moments (System-GMM), and quantile regression (QREG). Furthermore, the study mobilized Dumitrescu and Hurlin's panel causality test to examine the causal relationship between the variables under study. The results suggest that economic freedom has a direct and indirect negative effect on carbon emissions and that renewable energy consumption mediates the effect of economic freedom on carbon emissions. These results remained unchanged at the battery of robustness checks. Moreover, Dumitrescu and Hurlin's panel causality test results indicated a bidirectional causal relationship between economic freedom, renewable energy consumption, economic growth, economic globalization, and population size with carbon emissions. The various empirical findings have helped to formulate useful policy implications for policy-makers to ensure environmental sustainability., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Population aging, economic globalization, and economic growth simultaneously cause changes in environmental quality, but so far no studies have integrated these key factors into the same environmental policy framework. Thus, this study uses the more robust Westerlund cointegration test and the augmented mean group (AMG) estimator (robust to cross-sectional dependence (CD), heterogeneity, and endogeneity) to estimate the long-term relationship between population aging, economic globalization, economic growth, and per capita carbon emissions in East Asian countries during the period 1975-2018. The analysis results reflect that population aging significantly reduces the long-term per capita carbon emissions of specific East Asian countries. However, energy generation and economic globalization make significant contributions to long-run per capita carbon emissions. Moreover, the impact of economic growth on long-term per capita carbon emissions is significantly positive, while the impact of square of economic growth on long-run per capita carbon emissions is significantly negative, thus validating the inverted U-shaped environmental Kuznets curve (EKC) hypothesis for specific East Asian countries. The results of the causality test indicated a two-way causality between energy generation and per capita carbon dioxide emission, supporting the feedback hypothesis. There is also a two-way causal relationship between aging population and per capita carbon dioxide emission. Policy recommendations are discussed in response to the empirical findings of this study., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Human capital (HC) plays a crucial role in economic growth, and also has a considerable effect on environmental performance, including carbon emissions (CEs). Existing studies have drawn inconsistent conclusions on whether and how HC affects CEs, and most of them conduct case studies of a certain country or several countries with similar economic backgrounds. In order to accurately determine the effect and the influence mechanism of HC on CEs, this research conducted an empirical study by applying econometric method and the panel data of 125 countries over the period 2000-2019. The empirical results indicate that there is an inverted U-shaped nexus between HC and CEs of full sample countries, revealing that HC will increase CEs before turning point and decrease CEs after turning point. From a heterogeneity perspective, this inverted U-shaped nexus only exists in high and upper-middle income countries, while is not supported in low and lower-middle income countries. This study further disclosed that HC can affect CEs by the mediating effects of labor productivity, energy intensity, and industrial structure from a macro perspective. Specifically, HC will increase CEs by promoting labor productivity, while decrease CEs by reducing energy intensity and the proportion of secondary industry. These results can provide important references for governments of different countries to make tailored carbon reduction policies according to the mitigation effect of HC on CEs., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)