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.      

Intertemporal Emission Permits Trading Under Uncertainty and Irreversibility

This paper analyzes the effect of emission permit banking on clean technology investment and abatement under conditions where the stringency of the future cap is uncertain. We examine the problem of heterogeneous firms minimizing the cost of intertemporal emission control in the presence of stochastic future pollution standards and emission permits that are tradable across firms and through time. A firm can invest in clean capital (an improved pollution abatement technology) to reduce its abatement cost. We consider two possibilities: that investment is reversible or irreversible. Uncertainty is captured within a two period model: only the current period cap is known. We show that if banking is positive and marginal abatement costs are sufficiently convex, there will be more abatement and investment in clean technology under uncertainty than there would be under certainty and no banking. These results are at odds with the common belief that uncertainty on future environmental policy is a barrier to investment in clean capital. Moreover, under uncertainty and irreversibility, we find that there are cases where banking enables firms to invest more in clean capital.     

Pollution Abatement Investment When Environmental Regulation Is Uncertain

In a dynamic model of a risk-neutral competitive firm that can lower its pollution emissions per unit of output by building up abatement capital stock, we examine the effect of a higher pollution tax rate on abatement investment both under full certainty and when the timing or the size of the tax increase is uncertain. We show that a higher pollution tax encourages abatement investment if it does not exceed a certain threshold rate. However, akin to the Diamond-Mirrlees tax anomaly, it is possible that a higher pollution tax rate results in more pollution. The magnitude uncertainty discourages abatement investment, but at the time of the actual tax increase the abatement investment path may shift either upward or downward. On the other hand, when the timing is uncertain, the abatement investment path always jumps upward, thus suggesting that the effect of magnitude uncertainty on the optimal investment path may be more pronounced than that of timing uncertainty. Further, we show that the ad hoc practice of raising the discount rate to account for the uncertainty leads to underinvestment in abatement capital. We show how the size of this underinvestment bias varies with the future tax increase. Finally, we show that a credible threat to accelerate the tax increase can induce more abatement investment.     

An alternative interpretation of multiple bounded WTP data—Certainty dependent payment card intervals

This paper analyzes the multiple bounded format, in which uncertainty is directly incorporated into the WTP question. A new approach for analyzing multiple bounded uncertainty data is presented. The intuition underlying the approach is that uncertain individuals would like to state their WTP as intervals rather than precise values and that the width of the intervals is determined by the degree of uncertainty. The approach is compared to the one applied in Welsh and Poe [Welsh, M., Poe, G.L., 1998. Elicitation effects in contingent valuation: comparisons to a multiple bounded discrete choice approach. Journal of Environmental Economics and Management 36, 170–185] which treats uncertainty by conditioning responses on specific verbal probability statements. We argue that the conditioning approach overestimates mean and median WTP and that conditioning WTP estimates on probability statements like “probably” and “unsure” make them “fuzzy”. To empirically compare the two approaches we use data from 2004 concerning implementation of a predator protection policy in Sweden. Our analysis show that the suggested approach: (1) is more intuitive; (2) better fits the data; (3) estimates mean and median WTP with better precision; (4) is less sensitive to distributional assumptions; and (5) it is better suited for policy analysis.     

Dealing with preference uncertainty in contingent willingness to pay for a nature protection program: A new approach

In this paper, we propose an alternative preference uncertainty measurement approach where respondents have the option to indicate their willingness to pay (WTP) for a nature protection program either as exact values or intervals from a payment card, depending on whether they are uncertain about their valuation. On the basis of their responses, we then estimate their degree of uncertainty. New within this study is that the respondent's degree of uncertainty is “revealed”, while it is “stated” in those using existing measurement methods. Three statistical models are used to explore the sources of respondent uncertainty. We also present a simple way of calculating the uncertainty adjusted mean WTP, and compare this to the one obtained from an interval regression. Our findings in terms of determinants of preference uncertainty are broadly consistent with a priori expectations. In addition, the uncertainty adjusted mean WTP is quite similar to the one derived from an interval regression. We conclude that our method is promising in accounting for preference uncertainty in WTP answers at little cost to interviewees in terms of time and cognitive effort, on the one hand, and without researcher assumptions regarding the interpretation of degrees of uncertainty reported by respondents, on the other.     

Weitzman Revisited: Emission Standards Versus Taxes with Uncertain Abatement Costs and Market Power of Polluting Firms

Studies dealing with the optimal choice of pollution control instruments under uncertainty have invariably taken it for granted that regulated firms face perfectly competitive markets. By introducing the product market into the stochastic framework of Weitzman (Rev Econ Stud 41:477–491, 1974), this paper shows for the case of a polluting symmetric Cournot oligopoly that Weitzman’s policy rule for choosing emission standards versus taxes with uncertain abatement costs is biased in the presence of market power. Since the oligopolists take into account their influence on the market price, their total abatement effort, including the restriction of output, is less vulnerable to miscalculations of the tax rate compared to price-taking firms. Consequently, the comparative advantage of instruments is shifted in favour of taxes. In a further step, the provided policy recommendations are generalised by abolishing the assumption that firms are symmetric.     

Hypothetical Bias in Risk Preferences as a Driver of Hypothetical Bias in Willingness to Pay: Experimental Evidence

This study provides new insight on the established issue of elicitation bias in hypothetical choice settings. In particular, using an experiment that elicits real and hypothetical willingness to pay for the protection of otters, we provide evidence that the observed bias is driven by those who are both uncertain about their value and exhibit hypothetical bias in risk attitudes. This finding provides a reason why calibration approaches based on follow-up certainty questions have proven useful, but also suggests a degree of caution in applying the approach. Our results favour combining uncertainty calibration with CVM-X in which hypothetical bias in risk attitudes is also taken account to correct for hypothetical bias in WTP.     

Protesting and Justifying: A Latent Class Model for Contingent Valuation with Attitudinal Data

This article develops a latent class model for estimating willingness-to-pay (WTP) for public goods using simultaneously contingent valuation (CV) and attitudinal data to identify individuals with similar characteristics, such as WTP and protest attitudes. We find evidence that the answer to the CV question influences the responses to the attitudinal questions. In our case, this influence reflects rational behavior (budget constraint issues) and justification biases related to protest reasons, such as lack of trust in institutions or fairness issues with respect to the distribution of the burden of preservation. The results from our empirical application confirm the importance of accounting for those biases.     

The Implications of Uncertainty for Monetary Policy

This paper uses a simple model of the Australian economy to empirically examine the consequences of parameter uncertainty for optimal monetary policy. Optimal policy responses are derived for a monetary authority that targets inflation and output stability. Parameter uncertainty is characterised by the estimated distribution of the model coefficient estimates. Learning is ruled out, so the monetary authority can commit to its ex ante policy response. For certain shocks, taking account of parameter uncertainty can recommend more, rather than less, activist use of the policy instrument. While this finding is specific to the model specification, parameter estimates and the shocks analysed, it contrasts with the widely held belief that the generic implication of parameter uncertainty is more conservative policy.     

Technology-forcing through environmental regulation

This paper analyzes the demand characteristics of innovation in pollution abatement and the interaction between a regulator and a polluter under a technology-forcing policy. Important demand-driven determinants of innovation in pollution control are examined, such as uncertainties surrounding unexplored technologies, the length of the compliance period and the maximum abatement costs the regulator is willing to accept. We derive the formal condition that the regulator balances the marginal utility of emissions reduction against the marginal disutilities of a longer compliance time and the increased uncertainty about the feasibility of a more stringent standard.     

A CONTINGENT VALUATION STUDY OF UNCERTAIN ENVIRONMENTAL GAINS

Acid deposition in a present and future cause of biodiversity losses in vulnerable upland areas of Scotland important for nature conservation. However, the exact nature of damages under the status quo, and both the timing and extent of recovery of upland ecosystems if deposition is reduced, are subject to uncertainty. this uncertainty complicates damages cost estimation. In this paper, we have explored the use of CVM to measure the willingness to pay (WTP) of the Scottish population for uncertain recovery/damage scenarios from reduced acid rain deposition. An optimally-designed referendum format was used utilising the distribution of open-ended bids from a pilot study to determine bid amounts and sampling size for each bid amount. Eight explanatory variables, including future damage level were selected in a non-linear step-wise regression analysis. Average household WTP for abatement of acid rain was £247 and £351 per year when faced with low and high future damage levels respectively. Recovery level and recovery time did not significantly influence WTP. When faced with risky outcomes regarding future damage and recovery level, respondent were found to be risk averse to both environmental gains and losses.     

Strategic Behavior,Private Information,and Decentralization in the European Union Emissions Trading System

In the European Union Emissions Trading System, the supply of carbon permits is determined in a decentralized manner by Member States. Alternatively, the supply could be determined by an EU central authority. We analyze whether decentralization leads to lower total abatement costs under various assumptions about the behavior of Member States and the privacy of information about their abatement costs. If Member States do not behave strategically, then decentralization is preferred, regardless of whether abatement costs are private information. If the Member States behave strategically, then decentralization may or may not be preferred, depending on the degree of uncertainty about abatement cost parameters, the variation in emission endowments, and the number of Member States.     

Climate Policy,Learning, and Technology Adoption in Small Countries

A significant reduction in global greenhouse gas emissions requires international cooperation in emission abatement as well as individual countries’ investment in the adoption of abatement technology. The existing literature on climate policy pays insufficient attention to small countries, which account for a substantial proportion of global emission. In this study, we investigate how climate policy and learning about climate damage affect investment in abatement technology in small countries. We consider three alternative climate policy instruments: emission standards, harmonized taxes and auctioned permits. We say that learning is feasible if an international environmental agreement (IEA) is formed after the resolution of uncertainty about climate damage. We find that, either with learning and quadratic abatement costs or without learning, harmonized taxes outperform emission standards and auctioned permits in terms of investment efficiency. Without learning, a large cost of nonparticipation (that a country incurs) in the IEA can be beneficial to the country. Whether learning improves investment efficiency depends on the size of this nonparticipation cost.     

Efficient Dynamic Pollution Taxation in an Uncertain Environment

This paper analyzes efficient pollution taxation within a stochastic model of endogenous growth. Pollution is a by-product of production and causes disutility. Furthermore, the productivity which results from environmental quality is uncertain. This reflects e.g. uncertain capital depreciation induced by natural disasters like hurricanes or floods. This uncertainty is shown to raise an ambiguous impact on the optimal pollution level as well as on optimal environmental taxation. Market equilibrium turns out to be suboptimal, since the households mis-perceive their individual impact on pollution. Conditions for welfare maximizing pollution taxation are stated and it is shown that a direct pollution tax is not appropriate to yield Pareto-optimal growth. Instead, a linear capital income tax together with a linear abatement subsidy build an efficient tax scheme, if secondarily the governmental budget is balanced. Moreover, an increase in the riskiness of environmental productivity may even lead to an increase in the optimal pollution level and to a decrease in optimal environmental taxation, depending predominantly on the preference parameters.      

Policy choice for end-of-pipe abatement technology adoption under technological uncertainty

Regulators have increasingly become concerned about end-of-pipe abatement technologies because they not only play a crucial role in air pollution control but also ensure the achievement of the deep carbon emissions reduction target. This paper investigates the effect of emission taxes and standards on the adoption of end-of-pipe abatement technology when the arrival time and degree of improvement of the new emissions abatement technology are uncertain. We find that the ranking of emission taxes and standards in terms of motivating early adoption depends on the policy stringency. More specifically, for high levels of environmental stringency, standards induce an earlier technology adoption than taxes, while the opposite conclusion holds for low levels of environmental stringency. The sensitivity analysis shows that these findings are robust to various relevant crucial parameters. Finally, the implications for the choice of environmental policy have been provided.     

Cost Uncertainty and Unilateral Abatement

Unilateral abatement is sometimes advocated in order to set a good example that will make other countries follow. The aim of this paper is to investigate whether existence of correlated cost uncertainty provides an incentive for a country to undertake unilateral abatement. The theoretical model is driven by two main mechanisms; first, a learning effect, as the follower country might reduce its risk premium as it can observe the cost level in the leader country. Second, there is the public good effect, i.e., the marginal benefit of abatement declines when abatement is a public good and other countries contribute to pollution reductions. Results shows that unilateral abatement would be efficient in reducing uncertainty about the unit costs of abatement if a country with low cost uncertainty would undertake abatement first, while a country with initially high cost uncertainty would follow. However, countries may prefer to act simultaneously because of the larger uncertainties that are inherent in a sequential game.      

Random wastes,imperfect monitoring and environmental quality standards

This paper considers a firm's choice of optimal pollution abatement strategy in an environment where pollution licences are purchased through a market and a fine is levied for pollution in excess of the licences held. The pollution associated with any level of abatement is stochastic and the authority monitors pollution via a random sample of observations. Firms choose cost-minimising values for the mean and variance of emissions and the authority selects its sample size and the number of licences issued to achieve an exogenous level of environmental quality with abatement costs and monitoring costs at a minimum level.     

Local Pollution in Federal Systems

It is widely accepted that decentralized control of local pollution is inefficient if the central and the local authorities are imperfectly informed. This paper shows how the central authority can introduce a flexible grant-in-aid system that induces the local authority to use a weighted combination of local and central information when the local authority suffers from confirmatory bias. If the central authority is highly uncertain about the environmental effects of a specific pollutant, the tax/subsidy scheme can be designed to allow local information to play an essential role in the environmental policy. If the central authority is certain that a pollutant must not exceed a specific limit, the tax/subsidy scheme can be designed to allow local information little influence on the environmental policy.     

Rethinking the optimal level of environmental quality: justifications for strict environmental policy

Traditional environmental theory suggests that the optimal level of a pollution emission occurs when the marginal damage created by the emissions is equal to the marginal cost of reducing the emissions. We argue that the benefits from reducing pollution should be much more broadly defined to include at least three other sources of benefits. First, we develop a game-theoretic model in which firms may under-invest in cost-saving ‘green technologies’. Second, we demonstrate that consideration of future damages and abatement costs leads to a lower current optimal pollution level than that obtained in traditional models. Finally, we show that ecological complexity creates indirect pathways by which greater pollution increases the likelihood of generating irreversible environmental damage. This broader definition of the benefits of pollution abatement yields an optimal level of pollution that may actually be less than the level at which conventionally-measured marginal damages are equal to marginal abatement costs. Thus, environmental policy should be stricter.     

Global Warming and a Potential Tipping Point in the Atlantic Thermohaline Circulation: The Role of Risk Aversion

The risk of catastrophes is one of the greatest threats of climate change. Yet, conventional assumptions shared by many integrated assessment models such as DICE lead to the counterintuitive result that higher concern about climate change risks does not lead to stronger near-term abatement efforts. This paper examines whether this result still holds in a refined DICE model that employs the Epstein–Zin utility specification and that is fully coupled with a dynamic tipping point model describing the evolution of the Atlantic thermohaline circulation (THC). Risk is captured by the possibility of a future collapse of the circulation and it is nourished by fat-tailed uncertainty about climate sensitivity. This uncertainty is assumed to resolve in the middle of the second half of this century and the near-term abatement efforts, which are undertaken before that point of time, can be adjusted afterwards. These modelling choices allow posing the question of whether aversion to this specific tipping point risk has a significant effect on near-term policy efforts. The simulations, however, provide evidence that it has little effect. For the more likely climate sensitivity values, a collapse of the circulation would occur in the more distant future. In this case, acting after learning can prevent the catastrophe, implying the remarkable insensitivity of the near-term policy to risk aversion. For the rather unlikely and high climate sensitivity values, the expected damage costs are not great enough to justify taking very costly measures to safeguard the THC. Our simulations also provide some indication that risk aversion might have some effect on near-term policy, if inertia limiting the speed of decarbonisation is accounted for. As it is highly uncertain how restrictive this kind of inertia will be, future research might investigate the effects of risk aversion if additional uncertainty about inertia is considered.