Pollution Stock Research Articles

A Dynamic Model for International Environmental Agreements

In this paper we develop a model that uses a dynamic framework to analyze the process through which countries join international environmental agreements (IEAs). In the model, while all countries suffer from the same environmental damage as a result of total global emissions, non-signatory countries decide on their emission levels by maximizing their own welfare, whereas signatory countries decide on their emission levels by maximizing the aggregate welfare of all signatory countries. It is assumed that signatory countries will be able to punish non-signatories, at some cost to themselves. When countries decide on their pollution emissions, they account for the evolution of the stock of pollution over time. Moreover, we propose a mechanism to describe how countries reach a stable IEA. The model is able to capture situations characterized by partial cooperation within an IEA that is stable over time. It also captures situations where all countries participate in a stable agreement, and situations where no stable agreement is feasible. Where more than one possibility coexist, the long-term outcome of the game depends on the initial conditions (i.e., the initial number of signatory countries and pollution level).

'The Voracity Effect' and Climate Change: The Impact of Clean Technologies

In the absence of a successful international cooperative agreement over the control of emissions there is a growing interest in the role that clean technologies may play to alleviate the climate change problem. Within a non-cooperative transboundary pollution game, we investigate, analytically and within a numerical example based on empirical evidence, the impact of the adoption of a cleaner technology (i.e., a decrease in the emission to output ratio). We show that countries may respond by increasing their emissions resulting in an increase in the stock of pollution that may be detrimental to welfare. This possibility is shown to arise for a significant and empirically relevant range of parameters. It is when the damage and/or the initial stock of pollution are relatively large and when the natural rate of decay of pollution is relatively small that the perverse effect of clean technologies is strongest. Cooperation over the control of emissions is necessary to ensure that the development of cleaner technologies does not exacerbate the free riding behavior that is at the origin of the climate change problem.

Stability of international environmental agreements: an illustration with asymmetrical countries

AbstractIn this paper we use a dynamic model to analyze the composition and stability of international environmental agreements (IEAs) in an asymmetrical framework. Signatory countries are assumed to optimize the total welfare of the international agreement's members, while non‐signatory countries optimize their own individual welfare, taking into account the dynamics of the pollution stock. Our model is calibrated using data from the MERGE climate policy assessment model. We briefly review two contrasting approaches to define stability of IEAs, and provide a numerical illustration in each case.

Sustainable development with stock pollution

ABSTRACTOptimal pollution control is an important challenge for sustainable development with three distinct cases. First, the situation where nature's assimilative capacity is completely destroyed involves normative problems that require further research. Second, environmental restoration with initial pollution above the steady-state stock requires an economy to initially allocate a relatively high share of its resources to cleaning-up activities. In return, this generally results in an intertemporally efficient development path that is both environmentally and economically sustainable. Third, optimal trajectories in situations with initial stocks of pollution below the long-term optimum generally imply an increase in pollution and a decline of optimal consumption. In this case, the investment of the environmental rents accruing from nature's assimilative capacity into man-made capital is required in analogy to the famous Hartwick rule to maintain a constant flow of instantaneous welfare. This would facilitate growth in consumption sufficient to compensate for the rising disutility of pollution.

Optimal Timing of Climate Change Policy: Interaction Between Carbon Taxes and Innovation Externalities

This paper addresses the impact of endogenous technology through research and development (R&D) on the timing of climate change policy. We develop a model with a stock pollutant (carbon dioxide) and abatement technological change through R&D, and we use the model to study the interaction between carbon taxes and innovation externalities. Our analysis shows that the timing of optimal emission reduction policy strongly depends on the set of policy instruments available. When climate-specific R&D targeting instruments are available, policy has to use these to step up early innovation. When these instruments are not available, policy has to steer innovation through creating demand for emission saving technologies. That is, carbon taxes should be high compared to the Pigouvian levels when the abatement industry is developing. Finally, we calibrate the model in order to explore the magnitude of the theoretical findings within the context of climate change policy.

Wastewater pollution abatement across an international border

ABSTRACTA differential game model is developed to compare incentives for wastewater pollution abatement of upstream and downstream countries under cooperative and noncooperative strategies. The Tijuana River is the empirical setting of water flow from south (Mexico) to north (US) where pollution stock accumulates. Asymmetry between the upstream and downstream countries for costs, damages, and emissions influences incentives to abate pollution. Cost minimization is achieved as the US can finance pollution abatement in Mexico. Game sharing rules (Shapley value, Chander–Tulkens rule, Helsinki rule, egalitarian rule) are analyzed. Financial transfers from two North American Free Trade Agreement (NAFTA) institutions are examined. In most cases of cooperation, transfer payments are positive from downstream to upstream for reductions in flow and stock of pollution. Transfer size varies according to the rule and sensitivity analysis of changes in abatement costs and damages. The two institutions follow a variation of the Helsinki rule.

Global Pollution, Dynamic and Strategic Policy Interactions, and Long-run Effects of Trade

This paper examines the effects of international trade in a model with global pollution that accumulates over time because of production emissions in each country. If countries cooperatively determine the national environmental policies, the long-run stock of global pollution under trade may or may not be higher than that under autarky, depending on abatement technologies and trade costs. If environmental policies are determined noncooperatively, there may be multiple equilibria. This means that the long-run effect of trade on the global environment may be indeterminate because it depends on, in addition to trade costs and abatement technologies, the actually implemented policy. The welfare consequences of trade are also discussed.

The Gains from Differentiated Policies to Control Stock Pollution when Producers Are Heterogeneous

AbstractWe derive optimal input taxes to control stock pollution problems generated by heterogeneous agents. The taxes vary over time and in response to differences of asset quality and technology choice. We also derive second‐best policies and compare them to the efficient policy and also among themselves. Different policies will affect the timing for when, and the extent to which, conservation technologies are adopted. A numerical example, based on the California drainage problem, shows significant efficiency gains from the optimal policy compared to no intervention, but much of the gains are lost with second‐best interventions. The gains from optimal policies do not always increase with the degree of heterogeneity.

The environmental Kuznets curve in a world of irreversibility

This paper develops an overlapping generations model where consumption is the source of polluting emissions. Pollution stock accumulates with emissions but is partially assimilated by nature at each period. The assimilation capacity of nature is limited and vanishes beyond a critical level of pollution. We first show that multiple equilibria exist. More importantly, some exhibit irreversible pollution levels although an abatement activity is operative. Thus, the simple engagement of maintenance does not necessarily suffice to protect an economy against convergence toward a steady state having the properties of an ecological and economic poverty trap. In contrast with earlier related studies, the emergence of the environmental Kuznets curve is no longer the rule. Instead, we detect a sort of degenerated environmental Kuznets curve that corresponds to the equilibrium trajectory leading to the irreversible solution.

The Environmental Kuznets Curve in a World of Irreversibility

We develop an overlapping generations model where consumption is the source of polluting emissions. Pollution stock accumulates with emissions but is partially assimilated by nature at each period. The assimilation capacity of nature is limited and vanishes beyond a critical level of pollution. We first show that multiple equilibria exist. More importantly, some exhibit irreversible pollution levels although an abatement activity is operative. Thus, the simple engagement of maintenance does not necessarily suffice to protect an economy against convergence toward a steady state having the properties of an ecological and economic poverty trap. In contrast with earlier related studies, the emergence of the environmental Kuznets curve is no longer the rule. Instead, we detect a sort of degenerated Environmental Kuznets Curve that corresponds to the equilibrium trajectory leading to the irreversible solution.

Energy substitutions, climate change and carbon sinks

We determine the optimal exploitation time-paths of two energy resources, one being depletable and polluting, namely a fossil fuel, the other being renewable and clean. These optimal paths are considered along with the two following features. First, the cumulative atmospheric pollution stock is set not to exceed some critical threshold and second, the polluting emissions produced by the use of fossil fuel can be reduced at the source and stockpiled in several carbon sinks of limited capacity. We show that, if the renewable resource flow is abundant, the optimal path requires that sequestration is implemented only once the ceiling is reached. Moreover, the reservoirs should be completely filled by increasing order of their respective sequestration costs.

Environmental Policy Implications of Extreme Variations in Pollutant Stock Levels and Socioeconomic Costs

Motivated by recent evidence on the possibility of jumps in carbon dioxide emission levels and abrupt increases in pollutant-related socio-economic costs, this paper uses a real options approach to examine their impact with respect to the optimal timing of environmental policies and the optimal emissions abatement level. To this end, we extend the methodology of Pindyck (2000) using jump diffusion processes. We show that if pollutant stock levels are subject to extreme variations and the emissions abatement level is chosen exogenously by the policymaker, then environmental policy measures should be taken earlier. A similar, yet more prominent, effect is observed under the assumption that pollutant-related socio-economic costs and benefits are expected to exhibit abrupt changes. However, different results are obtained when we examine simultaneously the two interrelated decisions, namely, the optimal timing of emissions abatement and the optimal abatement level. In this case, an increase in the size and/or probability of a jump, delays policy adoption but leads to higher optimal abatement.

Precautionary Principle and Robustness for a Stock Pollutant with Multiplicative Risk

The interest shown by policy makers and economists in the precautionary principle indicates the importance of model uncertainty in global warming policy. I show that through robust control, policy makers can implement the precautionary principle to regulate a stock pollutant, and I analyze its effect on expected steady state pollution taxes, stocks and welfare. The paper is broadly comprised of a theoretical part and an application to global warming policy. I find that: (1) an increase in either uncertainty about the model or risk about abatement cost increases expected steady state pollution taxes; (2) a robust policy is preferred for any level of model uncertainty and this preference increases for either higher model uncertainty or higher multiplicative risk and (3) the effect on expected steady state pollution taxes and stock of introducing model uncertainty is relatively small for high levels of model uncertainty. These results advocate using robust policies for a stock pollutant in the presence of model uncertainty.

Nutrient load modelling during floods in intermittent rivers: An operational approach

In the Mediterranean area, lagoons and coastal waters are often under the influence of intermittent rivers that contribute the majority of pollutant loads during flood events. Reliable tools for evaluating pollutant loads from land sources are needed for managing the water quality of the receiving waters, but available water quality models are not suitable for simulating these flash flood events. An operational tool, D-PoL (Diffuse-Pollution Load), to estimate the pollutant loads transferred during rainfall events by small Mediterranean rivers is described. The tool is based on a rainfall-load semi-distributed approach and was developed with the aim of simulating temporal variations in fluxes of dissolved pollutants. The model simulates pollutographs at the outlet of the catchment during rainfall events: the rainfall triggers the processes. The model can be described as a rainfall-load model. Three parameters describe the processes involved: the initial stock of pollutants on the hillslopes, the production parameter (which is related to the lag time of the catchment) and the routing parameter (which is related to the lag time of a basic river reach). First, sensitivity analysis demonstrated that each of the parameters controlled one key-feature of the pollutograph. The initial stock of pollutants influenced the amplitude of the pollutograph, the production parameter controlled the recession period, and the routing parameter influenced the rising phase. Second, the model was calibrated for dissolved inorganic nitrogen and dissolved phosphorus on a 20-flood data set. The sets of optimal parameters were fitted to empirical relationships for both elements. On the 20-flood calibration data set, the simulated total loads with adjusted parameters compared well with the observed parameters, except for very small events. Finally, the D-PoL model was checked against a new set of data, a 10-flood validation data set. This final validation of the model showed that the dynamics of the pollutograph were not perfectly reproduced, but that simulated total loads agreed with the observed loads.

An infinite-horizon model of dynamic membership of international environmental agreements

Much of the literature on international environmental agreements (IEAs) uses static models, although most important transboundary pollution problems involve stock pollutants. The few papers that study IEAs using models of stock pollutants do not allow for the possibility that membership of the IEA may change endogenously over time. In this paper we analyse a simple infinite-horizon version of the static model of self-enforcing IEAs, in which damage costs increase with the stock of pollution, and countries decide each period whether to join an IEA. Using a quadratic approximation of the value function of the representative country we show that there exists a steady-state stock of pollution with corresponding steady-state IEA membership, and that as the stock rises towards steady state the IEA membership falls. Moreover, we find that the greater is the cost of damage, and hence the greater are the potential gains from cooperation, the smaller is the membership of a self-enforcing IEA.

Agroecosystem modeling and optimal economic decisions: Implications for sustainable agriculture

AbstractWe adapt a biogeochemical model of an agroecosystem to account for optimal economic behavior on the part of agricultural producers. Two institutional management regimes are considered: one in which a representative producer does not account for stock pollution caused by use of agricultural inputs, and one in which the externality is internalized. Comparative statics of the steady state of the former problem are analyzed in order to gain insight into the effects of potential policy and technological changes. Results show that a more realistic ecosystem component that includes nutrient cycling can qualitatively change optimal management practices relative to a one‐state representation, potentially rendering systems ‘unsustainable’ under some criteria and leading to policy instruments that exacerbate, rather than mitigate, external damages or the resource base. Moreover, the qualitative effect of changes in model parameters are not necessarily uniform across different agricultural systems, implying that a prescription for the so‐called ‘sustainable’ management under one system may have unintended consequences under another system. Copyright © 2007 John Wiley & Sons, Ltd.

A dynamic model of food and clean energy

In the midwestern United States, ethanol produced from corn is mixed with gasoline to meet clean air standards. Allocating land to produce clean fuel means taking away land from farming. We examine the use of a scarce fossil fuel that causes pollution but may be substituted by a clean fuel produced from land. When land is scarce, it is gradually shifted away from farming to energy production. However, when land is abundant, there may be a jump in the supply of clean energy. When the stock of pollution is regulated, the supply of clean energy may exhibit multiple discontinuities.

Innovation without magic bullets: Stock pollution and R&D sequences

We study the optimal R&D trajectory in a setting where new technologies are never perfect backstops in the sense that there is no perfectly clean technology that eventually solves the pollution problem once and for all. New technologies have strings attached, i.e. each emits a specific stock pollutant. Damages are convex in individual pollution stocks but additive across stocks, creating gains from diversification. The research and pollution policies are tightly linked in such a setting. We derive the optimal pollution path and R&D program. Pollution stocks overshoot and in the long-run all available technologies produce. Research is sequential and the optimal portfolio of technologies is finite.

Environmental policy implications of extreme variations in pollutant stock levels and socioeconomic costs

This paper uses a real options approach to examine the impact of abrupt increases in carbon dioxide emissions and pollutant-related socio-economic costs. It derives optimal investment rules in the form of critical values for both pollutant stock levels and social costs, above which environmental policies should be adopted. Moreover, it determines the optimal emissions abatement level. Our analysis extends the methodology of Pindyck (2000) using jump diffusion processes. We show that if the stock of pollutant is subject to extreme variations and the emissions abatement level is chosen exogenously by the policymaker, then lower levels of the pollutant stock are required to trigger policy adoption. A similar, yet more prominent, effect is observed under the assumption that pollutant-related socio-economic costs and benefits are expected to exhibit abrupt changes. However, different results are obtained when we examine simultaneously the two interrelated decisions, namely, the optimal threshold of emissions abatement and the optimal abatement level. In this case, an increase in the size and/or probability of a jump increases the critical values of both pollutant stock levels and socio-economic costs but leads to higher optimal abatement.

Maritime trade and migratory species management to protect biodiversity

Invasive species threaten biodiversity worldwide. Ships inadvertently carry marine invasive species to vulnerable ports. An empirical game theoretic analysis is presented to explore this transboundary biological pollution topic. This analysis utilizes data on marine invasive species and maritime trade as a vector of impact on native species at different public port locations along the Pacific coast of the North American countries. Preventative and reactive abatement strategies are compared. The countries are not identical and a comparison of noncooperative game strategies and payoffs to the cooperative game is presented. With the asymmetry between countries, optimal sharing rules are quantified. Results show that cooperative and preventative abatement is optimal compared to all other strategies dealing with stock and flow pollution.