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Several countries have imposed either a ban or a tax on single-use plastic packaging, motivated by their contribution to marine plastic pollution. This may lead consumers to opt for similar unregulated substitutes, potentially undermining or even counteracting the intended effect of the policy instrument. The purpose of this study is to theoretically and empirically compare the environmental and welfare effects of the first-best Pigouvian taxes on both plastic bags and a substitute (paper bags), with two alternative second-best policy instruments: a tax on plastic products alone, and a common uniform tax on all packaging materials. The empirical analysis accounts for two different types of environmental externalities from the use of both bag types: marine pollution and greenhouse gas emissions. It also compares results for two countries, Denmark and the USA, which differ in the demand for plastic and paper bags. The theoretical analysis shows that a unilateral tax on plastic bags should equal the marginal environmental damage of plastic bags minus a fraction of the marginal environmental cost of paper bags, hence being lower than the Pigouvian tax. The optimal common tax should equal a weighted average of the marginal environmental damage of the two bag types and would be lower than the Pigouvian tax on plastics if the marginal external cost of plastic bags exceeds that for paper bags. The empirical analysis shows that for default parameters, the variation in tax level across the studied scenarios is small. It also shows that if Pigouvian taxes cannot be implemented, a common uniform tax on both bag types would result in a higher welfare gain than a tax on plastic bags alone. Sensitivity analysis reveals that the level of the second-best taxes and their associated environmental and welfare impacts are sensitive to assumptions regarding the littering rate and decay rate of plastic bags in the marine environment. • A separate tax on plastic bags leads to substitution towards unregulated products. • Both plastic bags and substitutes cause marine pollution and GHG emissions. • We estimate first and second-best environmental taxes on plastic and paper bags. • Pigouvian taxes on both plastic and paper bags yield the highest welfare effect. • A uniform tax on all bags yields higher welfare than a single tax on plastic bags. [ABSTRACT FROM AUTHOR]

As the global carbon emission problem is getting more and more serious, the European Union has proposed the Carbon Border Adjustment Mechanism (CBAM) to prevent carbon leakage, which will have an impact on China's foreign trade. Based on this background and the problems of current research that ignores factors such as commodity prices, long-term impacts, intertemporal substitution analysis, and changes in national strategies for foreign exports, this paper propose a Computable General Equilibrium (CGE) model based on an evolutionary game as a dynamic recursive basis to study the impact of the CBAM on the Chinese manufacturing industry. For the industries mentioned in the CBAM, 18 affected sectors are collated, and a CGE model containing multiple blocks such as production, trade, and carbon emissions is built. Meanwhile, we establish an evolutionary game model with EU suppliers, manufacturers, and the government, allowing Chinese suppliers to compete with EU suppliers. Based on the above model, the impact of carbon tariff policies from 2020 to 2050 is studied. The results indicate that under the intra-EU competition condition, carbon tariffs will reduce the price of Chinese exports and slightly decrease China's real GDP, as well as the carbon emission intensity of 18 sectors and fossil energy. However, the impact of carbon tariffs on overall carbon emissions is small and is essentially a protective policy. In addition, the evolutionary game-based CGE model takes into account the dynamic strategies of both sides and is therefore less affected by carbon tariff shocks and recovers more quickly and more realistically. Finally, the article argues that the advantage of carbon tariffs for local suppliers is unsustainable and Chinese suppliers will still dominate, and local suppliers need more subsidies from the EU government. On the other hand, the Chinese government needs to implement a stricter carbon tax regime and export subsidies to improve the competitiveness of Chinese products in terms of green levels and price advantages. The purpose of this paper is to examine the quantitative impacts of CBAM on China's related manufacturing industries and strategies to maximize the benefits to both governments. • A new dynamic recursive approach to CGE is proposed that uses evolutionary games. • The strategy of the importing country is taken into account in the CGE model and is changed according to the multi-stage game strategy to simulate reality better. • The influencing factors of export commodity prices are explored, including the effects of consumer sensitivity, green input coefficients, and carbon emission rights prices. • The impact of CBAM on the income and savings of firms in 18 sectors in China to 2050 was studied. • The impact of CBAM on the carbon intensity of China's fossil energy sources, Coal, Oil, and Gas, the carbon intensity of enterprises in 18 sectors, and the national carbon emissions to 2050 were studied. [ABSTRACT FROM AUTHOR]

Compared to conventional abatement measures, Reducing Emissions from Deforestation and Forest Degradation (REDD) offers attractive cost savings while tackling the climate change problem. However, there exist challenges associated with the selection of the optimal level of REDD-based abatement given the risks and non-uniform costs of their implementation across countries. This paper develops an integrated assessment model of carbon mitigation, incorporating the REDD option. Using a dynamic optimization framework, it derives the optimal timing and level of REDD participation for key countries with REDD potential based on their opportunity costs and risks. Specifically, Brazil, Indonesia, the Democratic Republic of Congo, Cameroon and Papua New Guinea, are chosen for inclusion under the REDD-based abatement option. Together, these five countries account for roughly 20 percent of global forest area and 40 percent of current global deforestation. The relevance and contribution of REDD-based abatement is explored under the possibility of non-linear damages resulting from increasing concentrations of greenhouse gases. Results indicate that the REDD programme is an attractive option to consider despite the associated risks of impermanence. Including the REDD option, in fact, also increases conventional abatement efforts because low costs of REDD reduce the overall abatement costs, thereby making it optimal to abate more. Further, use of REDD option helps stabilise the atmospheric carbon stock in the long term. Without REDD, atmospheric carbon concentrations would be higher by 800 billion tonnes in the next 300 years. Whereas, optimal implementation of REDD in just five countries would help avoid the release of about 80 billion tonnes of carbon in the next 50 years. • This paper develops an IAM for carbon mitigation incorporating the REDD option. • Investigates the influence of REDD option on overall carbon abatement levels. • Explores optimal REDD involvement when damages evolve non-linearly. • Models individual opportunity costs and risks for countries with large REDD potential. • Derives optimal involvement level through REDD for Brazil and Indonesia. [ABSTRACT FROM AUTHOR]

This paper examines the impact of carbon risk induced through carbon price uncertainty in cap-and-trade policies on the value of covered firms. Specifically, the study explores the effects of policy adjustments made at the start of the third phase of the European Union Emission Trading Scheme (EU ETS), which aimed to address an oversupply of carbon allowances. Using a difference-in-difference approach, we find that the resulting increase in policy-induced carbon risk led to value discounts for firms with insufficient carbon allowances to offset their emissions, even when carbon prices themselves remained low. The findings highlight the importance of carbon risk exposure and the resulting carbon risk channel that influences firm value in a cap-and-trade scheme. • Cap-and-trade schemes are the most prominently used tool to combat climate change. • Insight on how carbon risk in such a policy can alter firm value is lacking to date. • We focus on the largest multinational cap-and-trade scheme in the world, the EU ETS. • Using a diff-in-diff, we find evidence of value losses for firms lacking allowances. • Carbon risk exposure acts as channel to affect firm value. [ABSTRACT FROM AUTHOR]

Abstract This paper proposes a detailed mechanism for why exporting firms may have a lower emission intensity when emissions are subject to an environmental tax. This mechanism of our model is supported by Swedish firm-level data. Our mechanism runs through firms' endogenous investments in abatement. Firms' abatement investments depend on their production volumes, since a larger scale allows them to spread the fixed costs of abatement investment across more units. Production volumes increase in firm productivity and, as a consequence, firms' emission intensity is negatively related to firm productivity. Exporting also leads to higher production volumes and thereby to a lower emission intensity. Thus, trade has an effect on emissions independently of firm productivity. Trade therefore leads to higher but cleaner production. The overall effect of trade on emissions is neutral in our model. Trade liberalization does not affect aggregate emissions in our benchmark case of symmetric countries. [ABSTRACT FROM AUTHOR]

How does climate-change mitigation affect the aggregate consumption risk borne by future generations? In other words, what is the ‘climate beta’? In this paper we argue using a combination of theory and integrated assessment modelling that the climate beta is positive and close to unity for maturities of up to about one hundred years. This is because the positive effect on the climate beta of uncertainty about exogenous, emissions-neutral technological progress overwhelms the negative effect on the climate beta of uncertainty about the carbon-climate-response, particularly the climate sensitivity, and the damage intensity of warming. Mitigating climate change therefore has no insurance value to hedge the aggregate consumption risk borne by future generations. On the contrary, it increases that risk, which justifies a relatively high discount rate on the expected benefits of emissions reductions. However, the stream of undiscounted expected benefits is also increasing in the climate beta, and this dominates the discounting effect so that overall the net present value of carbon emissions abatement is increasing in the climate beta. [ABSTRACT FROM AUTHOR]

Chemical absorption with molten aluminum to abate tetrafluoromethane (CF 4 ) was investigated in this paper. The experiments were conducted at a series of different temperatures of 973 K, 1003 K, 1103 K, and 1188 K and the abatement rate of CF 4 was calculated. It was found that CF 4 can be adsorbed firstly and then react with molten aluminum automatically. The initial abatement rate of CF 4 in molten aluminum was 3.10 × 10 −2 mol·m −3 ·s −1 at 973 K, while it reached its maximum value of 1.08 × 10 −1 mol·m −3 ·s −1 at the temperature of 1103 K. The highest abatement efficiency was 48.4%, reached at 1003 K. Higher temperatures up to 1188 K did not affect the abatement efficiency, however, they accelerated slightly the initial reaction rate. The products of the chemical absorption are white solid AlF 3 and black graphite powder identified by XRD and SEM-EDS analysis. Due to density differences, solid AlF 3 and graphite powder in the product tend to accumulate on the top of molten aluminum where they form two separate layers. This makes them recover more easily. The gas-liquid reaction process between CF 4 and molten aluminum is accorded with the two-film theory model, diffusion process is considered to be the control step of the whole process. [ABSTRACT FROM AUTHOR]

Voluntary environmental programs have proven to be a viable tool of pollution abatement, supplementing the command-and-control approach and market-based policies such as emissions trading and taxes. These voluntary initiatives aim to achieve pollution reduction through several channels, including procedural changes, raw material changes, product and packaging redesign, and innovation in pollution control technologies. The ISO 14001 standard is such a voluntary program; first introduced in 1996 by the International Organization for Standardization (ISO), it has steadily grown since and has been widely adopted by organizations around the world. In this paper, we empirically study the effects of the ISO 14001 standard on carbon emissions using a panel dataset of Korean manufacturing firms. As the largest contributor to the warming of the earth's atmosphere, carbon emissions are the focus of national and international efforts to curb climate change. The Korean manufacturing industry is responsible for about 40% of greenhouse gases in the country and has experienced rapid growth in ISO 14001 certified facilities. Our econometric results indicate that ISO 14001 certification spurs a significant reduction in carbon emissions among certified firms, after accounting for its potential endogeneity with an instrumental variable strategy. The empirical results suggest that wider ISO 14001 certification among carbon-intensive industries can be a credible pathway to help achieve the Korean government's goal of cutting domestic carbon emissions by 37% by 2030. • Impact of ISO 14001 certification on carbon emissions at the firm level. • Econometric analysis based on panel data of South Korean firms for the 2011–14 period. • The South Korean manufacturing industry is responsible for about 40% of greenhouse gases in the country. • The results show that ISO adoption spurs a 34% reduction in carbon emissions on average. • The reductions are larger in the first years after certification but linger for a number of years. [ABSTRACT FROM AUTHOR]

As the country with the highest carbon emissions, the main focus of China has become carbon reduction. At present, the governance of carbon reduction is mainly based on the division of administrative regions, which leads to the governance inefficiency and high costs because of spatial spillover and regional mobility of carbon emissions. The need for collaborative governance to promote carbon reduction performance has been recognized. However, because of differences in both costs and benefits between developed and less developed regions, a clear cost and benefit allocation mechanism must be established first. Fairness is very important when all members are to actively participate in collaborative carbon emission reduction efforts. In this paper, one of the regions renowned for collaborative governance—the Yangtze River Delta region—is used as example, and a cost-benefit allocation mechanism is constructed that incorporates members' fairness concerns. The carbon emission efficiency, carbon reduction efforts, and total carbon emission amount are compared under two scenarios: a cost-sharing scenario and a centralized decision-making scenario. The results indicate that, compared with the centralized decision-making scenario, the cost-sharing scenario achieved greater regional carbon reduction efforts, a higher carbon emission efficiency, and more total emissions. Furthermore, under the cost-sharing scenario, in less developed regions, fairness concerns increase carbon emission efficiency and total carbon emissions. The fairness concern in developed regions reduces the profit proportion, while the fairness concern in less developed region increases the profit proportion. The impact of fairness concern on carbon reduction is stronger in developed regions. • Carbon emissions from cost-sharing and centralized decision-making are compared. • Impacts of fairness concerns of local governments are considered. • A rational cost-benefit allocation mechanism is developed. • The centralized decision-making pattern is more efficient. [ABSTRACT FROM AUTHOR]

As a major carbon dioxide-emitting country, China set carbon trading market to reduce enterprise carbon emissions through the rational allocation of carbon quotas among different enterprises and regions. The market has also conducted a preliminary exploration for the country to achieve carbon dioxide emissions peak in 2030 and carbon neutrality in 2060 while actively addressing the challenges of global climate change. This study analysed the emission reduction effect of China's carbon trading pilot policy, especially the role of carbon quota and carbon trading price. The analysis used county-level panel data from 1997 to 2017, regarded the implementation of the carbon trading pilot policy as a quasi-natural experiment, and used the difference-in-differences method. The results showed that, first, the policy implementation not only reduced regional carbon emissions but also inhibited carbon dioxide emissions per capita, with long-term effects. Second, the carbon emission reduction effect brought by the carbon pilot policy showed significant heterogeneous results with the different degrees of regional carbon emissions and environmental supervision. The effect was greater in areas with higher carbon emission density and stronger legal supervision. Third, the difference in carbon quota allocations resulted in different emission reduction effects, among which the historical method had the strongest effect. The carbon quota price and number of enterprises participating carbon trading market were the key factors affecting carbon emission reduction. • This paper investigates the impact of carbon emission trading market on the carbon reduction. • China provides an excellent "Quasi-natural Experiment" for assessing the role of carbon emission trading market in environmental management. • It is found that policy implementation has significantly reduced various types of carbon emissions, and this reduction effect is long-term. • Stimulating the vitality of the carbon market and expanding the supply and demand of carbon quotas are the main ways to achieve carbon emission reduction. [ABSTRACT FROM AUTHOR]

To inform the decision makers the value of taking a watershed approach to managing land-based sources of pollution, this paper presented a systematic framework and models to estimate the minimum cost solutions of nutrient reduction in watershed. The established models considered the spatial heterogeneity of emissions sources, emission impact on the receiving waters, and the abatement cost. Empirical estimates in Jiulong River Watershed of China indicated that a 30% reduction of the nitrogen load to the receiving waters can be achieved by abating about 29% of total nitrogen emission and at a cost of RMB 263 million per year. Reduced applications of fertilizers and livestock holdings were the main abatement measures, and the urban sub-basins the main abatement regions due to their high abatement capacity. It was necessary to specify a target water body located in the middle or upstream of the watershed to capture the local damage of excessive nitrogen emission although this will generates a high cost and a high reduction. Sensitivity analysis indicated that for the same absolute values of load reductions, the emission reductions are more robust against changes in the retention and leakage parameters than that of the total cost. Additionally, changing the parameter values for abatement functions will only affect the total cost. [ABSTRACT FROM AUTHOR]

Titanium dioxide (TiO 2 ) is a popular photocatalyst used for many environmental and anti-pollution applications, but it normally operates under UV light, exploiting ∼5% of the solar spectrum. Nitrification of titania to form N-doped TiO 2 has been explored as a way to increase its photocatalytic activity under visible light, and anionic doping is a promising method to enable TiO 2 to harvest visible-light by changing its photo-absorption properties. In this paper, we explore the insertion of nitrogen into the TiO 2 lattice using our green sol–gel nanosynthesis method, used to create 10 nm TiO 2 NPs. Two parallel routes were studied to produce nitrogen-modified TiO 2 nanoparticles (NPs), using HNO 3 +NH 3 (acid-precipitated base-peptised) and NH 4 OH (totally base catalysed) as nitrogen sources. These NPs were thermally treated between 450 and 800 °C. Their true phase composition (crystalline and amorphous phases), as well as their micro-/nanostructure (crystalline domain shape, size and size distribution, edge and screw dislocation density) was fully characterised through advanced X-ray methods (Rietveld-reference intensity ratio, RIR, and whole powder pattern modelling, WPPM). As pollutants, nitrogen oxides (NO x ) are of particular concern for human health, so the photocatalytic activity of the NPs was assessed by monitoring NO x abatement, using both solar and white-light (indoor artificial lighting), simulating outdoor and indoor environments, respectively. Results showed that the onset of the anatase-to-rutile phase transformation (ART) occurred at temperatures above 450 °C, and NPs heated to 450 °C possessed excellent photocatalytic activity (PCA) under visible white-light (indoor artificial lighting), with a PCA double than that of the standard P25 TiO 2 NPs. However, higher thermal treatment temperatures were found to be detrimental for visible-light photocatalytic activity, due to the effects of four simultaneous occurrences: (i) loss of OH groups and water adsorbed on the photocatalyst surface; (ii) growth of crystalline domain sizes with decrease in specific surface area; (iii) onset and progress of the ART; (iv) the increasing instability of the nitrogen in the titania lattice. [ABSTRACT FROM AUTHOR]

Abstract: This paper examines how enforcement affects the structure and performance of emissions trading programs with price controls under uncertainty about firms' abatement costs. The analysis highlights how an enforcement strategy can cause abatement-cost risk to be transmitted to enforcement costs via the price of permits. When this occurs, accommodating the effect of abatement-cost risk with an optimal policy results in higher expected emissions and lower expected permit price than their second-best optimal values. However, it is possible to design an enforcement strategy that shields enforcement costs from abatement-cost risk by tying sanctions directly to permit prices. This enforcement strategy stabilizes enforcement effort, the optimal permit supply and price controls are independent of enforcement costs, and the policy produces the second-best optimal outcome. [Copyright &y& Elsevier]

Abstract: Sulfonylurea herbicides (SUHs) are a family of environmentally compatible herbicides but their high water solubility, moderate to high mobility through the soil profile, and slow degradation rate make them potential contaminants of groundwater as demonstrated in this paper. The photodegradation of a mixture of 30 SUHs in aqueous suspensions of semiconductor materials (ZnO and TiO2 in tandem with Na2S2O8 as electron acceptor) under artificial light (300–460 nm) irradiation was investigated. As expected, the influence of both semiconductors on the degradation of SUHs was very significant in all cases. Photocatalytic experiments show that the addition of photocatalyst, especially for the ZnO/Na2S2O8 system, greatly improves the removal of SUHs compared with photolytic tests, significantly increasing the reaction rates. The first-order equation (monophasic model) satisfactorily explained the disappearance process although it overlooked small residues remaining late in the process. These residues are important from an environmental point of view and the Hoerl function (biphasic model), was a better predicter of the results obtained. In our conditions, the average time required for 90% degradation was about 3 and 30 min for ZnO/Na2S2O8 and TiO2/Na2S2O8 systems, respectively. [Copyright &y& Elsevier]

Abstract: This review provides a short introduction to photocatalysis technology in terms of the present environmental remediation paradigm and, in particular, NO x photoabatement. The fundamentals of photoelectrochemical devices and the photocatalysis phenomena are reviewed, highlighting the main reaction mechanisms. The critical historical developments on heterogeneous photocatalysis are briefly discussed, giving particular emphasis to the pioneer works in this field. The third part of this work focus mainly on NO x removal technology considering topics such as: TiO2 photochemistry; effect of the operating conditions on the photocatalysis process; Langmuir–Hinshelwood modeling; TiO2 photocatalytic immobilization approaches; and their applications. The last section of the paper presents the main conclusions and perspectives on the opportunities related to this technology. [Copyright &y& Elsevier]

Abstract: This paper extends the voluntary-threat approach of Segerson and Wu (2006) to the case that the ambient level of nonpoint source pollution is stochastic. It is shown that when the random component is bounded from the above, fine-tuning the cutoff value of the tax payments avoids the actual imposition of the tax while the threat of such payments retains necessary incentive for the polluters to engage in abatements at the optimal level. If the random component is not bounded, the imposition of the tax cannot be completely avoided but the probability can be reduced by setting a higher cutoff value. It is also noted that the regulator has additional flexibility in randomizing the tax imposition but the randomization process has to be credible. [Copyright &y& Elsevier]

In this paper, a switchable multifunctional elastic metasurface is proposed to manipulate the transmitted plate waves. The flexural-dominated plate wave mode is concerned. The subwavelength functional unit of the designed metasurface looks like a "fish-bone" structure with nuts as vibrators. The positions of the nuts can be tuned continuously by screwing in or out, changing the phase shift in a full 2 π span with high transmission. The tunability of the phase shift is demonstrated both numerically and experimentally, and can be interpreted by the dispersion properties of the wave propagating through the fish-bone like functional unit. Finally, according to the generalized Snell's law, broadband switches of an elastic metasurface between several functions including the directional refraction, wave focusing and beam self-bending are simulated numerically by just screwing in or out the nuts (vibrators). [ABSTRACT FROM AUTHOR]