uncertainty and endogenous technical change in climate policy models until recently endogenous technical change and uncertainty have been modeled separately in climate policy models in this paper we review the emerging literature that considers both these elements together taken as a whole the literature indicates that explicitly including uncertainty has important quantitative and qualitative impacts on optimal climate change technology policy

climate change uncertainty irreversibility and the precautionary principle this paper begins with a critique of the option value argument used by economists to explain and justify the precautionary principle the argument is shown to misrepresent both uncertainty and irreversibility an alternative justification of the precautionary principle is discussed under conditions of keynesian uncertainty and irreversibility interpreted in terms of incommensurability recent formal decision theories under keynesian uncertainty are reviewed and their limitations explored with particular reference to the insights that decision theory can bring to understanding the precautionary principle throughout the decision problems under consideration are those faced by climate change policy makers copyright oxford university press

active learning and optimal climate policy this paper develops a climate economy model with uncertainty irreversibility and active learning whereas previous papers assume learning from one observation per period or experiment with control variables to gain additional information this paper considers active learning from investment in monitoring specifically in improved observations of the global mean temperature we find that the decision maker invests a significant amount of money in climate research far more than the current level in order to increase the rate of learning about climate change this helps the decision maker make improved decisions the level of uncertainty decreases more rapidly in the active learning model than in the passive learning model with only temperature observations as the uncertainty about climate change is smaller active learning reduces the optimal carbon tax the greater the risk the larger is the effect of learning the method proposed here is applicable to any dynamic control problem where the quality of monitoring is a choice variable for instance the precision at which we observe gdp unemployment or the quality of education

the irreversibility effect in environmental decisionmaking we provide a new more general definition for the irreversibility effect and demonstrate its relevance to problems involving environmental and other decisions under uncertainty we establish several analytical and numerical results that suggest both that the effect holds more widely than generally recognized and that an existing result epstein s theorem giving a sufficient condition for determining whether the effect holds can be applied more widely than previously indicated in particular to problems involving intertemporally nonseparable benefit functions we further show that a low elasticity of intertemporal substitution will however result in failure of the effect

environmental regulation with technology adoption learning and strategic behavior we analyze a model of environmental regulation with learning about environmental damages and endogenous choice of emissions abatement technology by a polluting firm we compare environmental policy under discretion in which policy is updated upon learning new information versus under rules in which policy is not updated when investment in abatement technology is made prior to the resolution of uncertainty neither discretion nor rules with either taxes or standards achieve an efficient solution except in special cases when there is little uncertainty rules are superior to discretion because discretionary policy gives the firm an incentive to distort investment in order to influence future regulation however when uncertainty is large discretion is superior to rules because it allows regulation to incorporate new information taxes are superior to standards under discretion regardless of the relative slopes of marginal costs and marginal damages for the case of quadratic abatement costs and damages

global warming irreversibility and learning a number of economists have argued that the literature on the irreversibility effect implies that current abatement of greenhouse gas emissions should be greater when there is the possibility of obtaining better information in the future about the potential damages from global warming than when there is no possibility of obtaining better information in this paper we show that even the simplest model of global warming does not satisfy either of epstein s 1980 sufficient conditions so it is not possible to use epstein s analysis to tell whether the irreversibility effect applies to models of global warming we derive an alternative sufficient condition for the irreversibility effect to hold

climate policy under uncertain and heterogeneous climate damages we highlight that uncertainty about climate damages and the fact that damages will be distributed heterogeneously across the global population can jointly be an argument for substantially stricter climate policy even if uncertainty and heterogeneity in isolation are not the reason is that a given climate risk borne by fewer people implies greater welfare losses however these losses turn out to be significant only if society is both risk and inequality averse and if climate damages are highly heterogeneous we discuss how insurance and self insurance of climate risk could theoretically mitigate this joint effect of uncertainty and heterogeneity and thus admit weaker climate policy insurance provides more efficient risk sharing and self insurance allows strongly impacted individuals to compensate damages by increasing savings we first use a simple analytical model to introduce the different concepts and then provide more realistic results from the integrated assessment model dice

the role of uncertainty and learning for the success of international climate agreements abstract transnational externalities e g transboundary pollution trade contagious diseases and terrorism warrant coordination and cooperation between governments but this proves often difficult one reason for the meager success is the public good character of many of these economic problems encouraging free riding another reason one might suspect is uncertainty surrounding most environmental problems and in particular climate change this provides often an excuse for remaining inactive paradoxically some recent papers have concluded just the opposite the veil of uncertainty can be conducive to the success of international environmental cooperation in this paper we explain why and under which conditions this can be true however we argue that those conditions are the exception rather than the rule most important we suggest a mechanism for those conditions where learning has a negative effect on the success of cooperation which removes this effect or even turns it into a positive effect our results apply beyond the specifics of climate change to similar problems where cooperation generates positive externalities

optimal learning on climate change why climate skeptics should reduce emissions climate skeptics typically argue that the possibility that global warming is exogenous implies that we should not take additional action towards reducing emissions until we know what drives warming this paper however shows that even climate skeptics have an incentive to reduce emissions such a directional change generates information on the causes of global warming since the optimal policy depends upon these causes they are valuable to know although increasing emissions would also generate information that option is inferior due its irreversibility we show that optimality can even imply that climate skeptics should actually argue for lower emissions than believers

impact of pension privatization on foreign direct investment summary we explore the causal effect of market oriented pension reform on net foreign direct investment fdi inflows in latin america and among the transitional economies of eastern europe and central asia both of which have experienced waves of pension privatization and fdi over the last two decades with our balanced panel of 42 countries over the 1991 2006 period we implement fixed effects models controlling for the decision to enact full or partial privatization of the public pension system and several other covariates whose choice is informed by the rich empirical literature on fdi our econometric results indicate that pension privatization triggers a significant increase in net fdi inflows and that the effect does not wane over time we estimate that full privatization increases fdi as a percentage of gdp by about 57 ceteris paribus

uncertainty learning and international environmental policy coordination in this paper we construct a simple model of global warming which captures a number of key features of the global warming problem i environmental damages are related to the stock of greenhouse gases in the atmosphere ii the global commons nature of the problem means that these are strategic interactions between the emissions policies of the governments of individual nation states iii there is uncertainty about the extent of the future damages that will be incurred by each country from any given level of concentration of greenhouse gases but there is the possibility that at a future date better information about the true extent of environmental damages may become available an important aspect of the problem is the extent to which damages in different countries may be correlated in the first part of the paper we consider a simple model with two symmetric countries and show that the value of perfect information is an increasing function of the correlation between damages in the two countries in both the cooperative and non cooperative equilibria however while the value of perfect information is always non negative in the cooperative equilibrium in the non cooperative equilibrium there is a critical value of the correlation coefficient below which the value of perfect information will be negative in the second part of the paper we construct an empirical model of global warming distinguishing between oecd and non oecd countries and show that in the non cooperative equilibrium the value of perfect information for oecd countries is negative when the correlation coefficient between environmental damages for oecd and non oecd countries is negative the implications of these results for international agreements are discussed

looking for a guide to protect the environment the development of the precautionary principle abstract if the precautionary principle is to become the guide of the international community for environmental protection policies an economic interpretation of the principle is in order the analysis of case studies and a survey of the recent decision theoretic literature show the lack of a fully satisfactory economic model more generally various theoretical and empirical results show that the principle cannot be assumed to apply a priori though it has been proposed by international treaties as a rule of thumb for situations of scientific uncertainty the precautionary principle could actually be inefficient

a cost benefit analysis of slowing climate change there are many conflicting views regarding the true dimensions of the climate change problem often these viewpoints are based on different estimates of key parameters with little indication as to why parameter estimates vary so much and which ones might be the more reliable the prospects for a co ordinated strategy to tackle climate change appear dim little consensus has emerged for example regarding the costs of abating carbon emissions some take the view that considerable improvements in energy efficiency are available at negative cost by setting minimum efficiency standards for vehicles and domestic appliances e g mills et al 1991 others regard the macroeconomic costs of even small reductions in carbon emissions as substantial manne and richels 1993 in the judgement of other researchers a proportion of carbon emissions arise purely as a result of institutional failings either at a regional level in the subsidies paid to fossil fuel energy producers in the erroneous belief that this promotes economic growth shah and larsen 1994 in failure to deal with air pollution glomsrod et al 1992 and vehicle congestion in urban areas hughes 1994 or at a global level in failing to make appropriate transfers to those countries whose forests contain rich biodiversity which we would wish to preserve pearce 1991

regulatory actions under adjustment costs and the resolution of scientific uncertainty food system regulators often decide whether to ban existing practices or approve new technologies without conclusive scientific evidence on possible damage and knowing that resolution is likely in the future in a model with three decision points and stochastic resolution of uncertainty we study interactions between expected losses due to regulation and information availability when a regulator is deciding on an early reversible ban and on a later reversible ban adjustment costs create inertia concerning intermediate signals such that earlier decisions are not overturned and also a bias against imposing an early ban the prospect of more later stage information can increase or decrease the incentive to ban early but research decreases the incentive to ban early

optimal climate policy is a utopia from quantitative to qualitative cost benefit analysis abstract the dominance of quantitative cost benefit analysis cba and optimality concepts in the economic analysis of climate policy is criticised among others it is argued to be based in a misplaced interpretation of policy for a complex climate economy system as being analogous to individual inter temporal welfare optimisation the transfer of quantitative cba and optimality concepts reflects an overly ambitious approach that does more harm than good an alternative approach is to focus the attention on extreme events structural change and complexity it is argued that a qualitative rather than a quantitative cba that takes account of these aspects can support the adoption of a minimax regret approach or precautionary principle in climate policy this means implement stringent ghg reduction policies as soon as possible

environmental prices uncertainty and learning there is an increasing demand for putting a shadow price on the environment to guide public policy and incentivize private behaviour in practice setting that price can be extremely difficult as uncertainties abound there is often uncertainty not just about individual parameters but about the structure of the problem and how to model it a further complication is the second best nature of real environmental policy making in this paper we propose some practical steps for setting prices in the face of these difficulties drawing on the example of climate change we consider how to determine the overall target for environmental protection how to set shadow prices to deliver that target and how we can learn from the performance of policies to revise targets and prices perhaps most significantly we suggest that estimates of the marginal cost of environmental protection rather than the marginal benefit will often provide the more consistent and robust prices for achieving targets

labor disputes and the economics of firm geography a study of domestic investment in india abstract acrimonious relations between employers and employees in developing countries have often been cited as impediments to progress this article considers various measures of labor disputes and investigates whether these have detrimental effects on the location choice of new domestic investment across the various states of india conventional wisdom holds that an increase in measures such as the number of strikes the number of man days lost in work stoppages and the percentage of unionized workers would hinder the location of new projects using panel data and a fixed effects methodology that controls for the effect of state specific unobservables we find significant evidence that this is indeed the case in india furthermore disaggregation by industrial classifications shows that although labor disputes continue to exert negative effects location choices are also conditioned on factors such as proximity to raw materials and minerals

climate change mitigation and adaptation with uncertainty and learning one of the major issues in climate change policy is how to deal with the considerable uncertainty that surrounds many of the elements some of these uncertainties will be resolved through the process of further research this process of learning raises a crucial timing question should society delay taking action in anticipation of obtaining better information or should it accelerate action because we might learn that climate change is much more serious than expected much of the analysis to date has focussed on the case where the actions available to society are just the mitigation of emissions and where there is little or no role for learning we extend the analysis to allow for both mitigation and adaptation we show that including adaptation weakens the effect of the irreversibility constraint and so for this model makes it more likely that the prospect of future learning should lead to less action now to deal with climate change we review the empirical literature on climate change policy with uncertainty learning and irreversibility and show that to date the effects on current policy are rather small though this may reflect the particular choice of models employed

regulation with anticipated learning about environmental damages a regulator anticipates learning about the relation between environmental stocks and economic damages for a model with linear quadratic abatement costs and environmental damages and a general learning process we show analytically that anticipated learning decreases the optimal level of abatement at a given information set if learning causes the regulator to eventually decide that damages are higher than previously thought learning eventually increases abatement learning also favors the use of taxes rather than quotas using a model that is calibrated to describe the problem of global warming we show numerically that anticipated learning causes a significant reduction in first period abatement and a small increase in the preference for taxes rather than quotas even if the regulator s initial priors about environmental damages are much too optimistic he is able to learn quickly enough to keep the expected stock trajectory near the optimal trajectory

optimists pessimists and the precautionary principle the precautionary principle has emerged as a leading guide to public decision making about environmental risks under irreversibility and uncertainty in this paper we adopt a two period model with irreversibility and agents differentiated by their degree of optimism to characterize the conditions under which the precautionary principle applies we show in particular that it is more often applied if the decision maker has an intermediate optimism index if scientific research is more effective at reducing uncertainty and if the same decision maker makes the decisions for both periods moreover we show that socially optimal decisions lead to apply the precautionary principle more often than an elected decision maker does

risk averse mitigation decisions in an unpredictable climate system risk aversion plays a central role in the decisions made in the face of uncertainties and climate change mitigation should be no exception however the interlinkage of risk aversion and climate change uncertainties has hardly been investigated numerically in part because of the computational difficulties of stochastic optimization in this paper we apply the numerical techniques of stochastic optimization to the economic modeling of climate change with the aim of modeling the decision preferences of a risk conscious agent in the face of unpredictable climate change the model underlines the critical role played by the risk aversion parameter in determining the effects of uncertainties on mitigation not only in level but also in sign

a dynamic game of emissions pollution with uncertainty and learning we introduce learning in a dynamic game of international pollution with ecological uncertainty we characterize and compare the feedback non cooperative emissions strategies of players when the players do not know the distribution of ecological uncertainty but they gain information learn about it we then compare our learning model with the benchmark model of full information where players know the distribution of ecological uncertainty we find that uncertainty due to anticipative learning induces a decrease in total emissions but not necessarily in individual emissions further the effect of structural uncertainty on total and individual emissions depends on the beliefs distribution and bias moreover we obtain that if a player s beliefs change toward more optimistic views or if she feels that the situation is less risky then she increases her emissions while others react to this change and decrease their emissions

research frontiers in the economics of climate change academic and policy debates over climate change risks and policies have stimulated economic research in a variety of fields in this article i briefly discuss eight overlapping areas of current research in which further effort is particularly warranted these areas include decision criteria for policy risk assessment and adaptation uncertainty and learning abatement cost and the innovation and diffusion of technology and the credibility of policies and international agreements further analysis in these areas not only will advance academic understanding but also will provide insights of considerable importance to policymakers

labor regulations and job quality evidence from india the authors examine whether measures of job quality in india s manufacturing sector differ systematically across states with varying types of labor regulation their analysis uses repeated cross sections of india s national sample survey organization nsso household survey data from 1983 to 2004 merged with data on state level regulations covering employment adjustment and dispute resolution results from a differences in differences procedure show that restrictions on employment adjustment and dispute settlement in a pro worker direction contribute to improved job quality for women along most measures such regulations yield mixed results for men however results indicate that higher wages come at the expense of fewer hours substitution toward in kind compensation and less job security the authors conclude that india s labor legislation does have a silver lining with respect to job quality but that silver lining applies selectively

optimal investment in clean production capacity for the mitigation of long term pollution threats one must consider that both the process of environmental degradation and the switchover to new and cleaner technologies are dynamic we develop a model of a uniform good that can be produced by either a polluting technology or a clean one the latter is more expensive and requires investment in capacity we derive the socially optimal pollution stock accumulation and creation of nonpolluting production capacity weighing the tradeoffs among consumption investment and djustment costs and environmental damages we consider the effects of changes in the pollution decay rate the capacity depreciation rate and the initial state of the environment on both the steady state and the transition period the optimal transition path looks quite different with a clean or dirty initial environment with the former investment is slow and the price of pollution may overshoot the long run optimum before converging with the latter capacity may overshoot

optimal climate change policies when governments cannot commit this paper examines the optimal design of climate change policies in the context where governments want to encourage the private sector to undertake significant immediate investment in developing cleaner technologies but the carbon taxes and other environmental policies that could in principle stimulate such investment will be imposed over a very long future the conventional claim by environmental economists is that environmental policies alone are sufficient to induce firms to undertake optimal investment however this argument requires governments to be able to commit to these future taxes and it is far from clear that governments have this degree of commitment we assume instead that governments cannot commit and so both they and the private sector have to contemplate the possibility of there being governments in power in the future that give different relative weights to the environment we show that this lack of commitment has a significant asymmetric effect compared to the situation where governments can commit it increases the incentive of the current government to have the investment undertaken but reduces the incentive of the private sector to invest consequently governments may need to use additional policy instruments such as r d subsidies to stimulate the required investment

quasi option value and climate policy choices in the climate change issue the environmental irreversibility risk of an acceleration of mitigation policies if the worst happens has to be balanced with the investment irreversibility risk of over cautious policies to explore this balance we define an option value for a precautionary climate policy using the simplest decision making model we expose how option value relates to the expected value of future information using quantitative data from an integrated assessment model we find that most of the time the environmental irreversibility dominates the investment irreversibility for all cases explored here the order of magnitude of the option value was significant about 50 of the opportunity cost

strategic exploitation with learning and heterogeneous beliefs abstract we study the effect of learning with heterogeneous beliefs on the exploitation of a renewable common pool resource to that end we extend the great fish war model of levhari and mirman 1980 to a learning environment in which several agents interact strategically and learn about the distribution of the stochastic evolution of the resource we find that the effect of anticipation of learning with heterogeneous beliefs is twofold first the anticipation of learning makes future payoffs more uncertain which induces the agents to decrease present exploitation due to the precautionary motive second under heterogeneity of beliefs there is a differential informational externality that induces the agents to increase or decrease present exploitation we also perform a comparative analysis on the cournot nash equilibrium with learning by studying the effect of optimism and riskiness on resource exploitation

uncertainty learning and heterogeneity in international environmental agreements this paper concerns the formation of international environmental agreements under uncertainty about environmental damage with different models of learning complete learning partial learning or no learning the results of the existing literature are generally pessimistic the possibility of either complete or partial learning generally reduces the level of global welfare that can be achieved from forming an iea relative to no learning that literature regards uncertainty as a parameter common to all countries so that countries are identical ex ante as well as ex post in this paper we extend the literature to the case where there is no correlation between damage costs across countries each country is uncertain about a particular parameter in our case the benefit cost ratio drawn from a common distribution but ex post each country s realized parameter value is independently drawn consequently while countries remain identical ex ante they may be heterogeneous ex post we show that this change reinforces the negative conclusions about the effects of partial learning on international environmental agreements but under certain conditions moderates the negative conclusions about the effects of complete learning

cold houses in warm climates and vice versa a paradox of rational heating houses in cold climates are kept warmer in winter than those in warm climates des pite the greater cost of heating in colder climates it is shown that this is not only consistent with but also implied by rationality the contrary intuition is based on a confusion between average and ma rginal cost the same analysis implies that it is rational to keep th e thermostat setting constant throughout the heating season rather th an changing it with changes in external temperature copyright 1987 by university of chicago press

global environmental risks the need to manage climate risks is not a new it has shaped social institutions for many centuries in medieval england a peasant farmer s land was broken into many widely dispersed parcels economic historians interpret this as a way of hedging climate risk see references in bromley 9 land in different locations would be affected differently by droughts floods and frosts by spreading land holdings over different locations as well as by organizing agricultural cooperatives and buying insurance farmers have managed climate risk for many centuries

optimal diversity increasing returns versus recombinant innovation abstract choices regarding diversity play an important role in economics and innovation management but often remain implicit once made explicit the objectives of efficiency and diversity are usually posed as in conflict as efficiency relates positively and diversity negatively to various increasing returns to scale in markets such a perspective however neglects the benefits of diversity in terms of realizing system improvements through recombinant innovation or spillovers the latter implies a contribution of diversity to long term efficiency dominant economic approaches that address diversity such as option value and real options theories regard benefits of diversity as exogenous this paper proposes a simple model of variable endogenous diversity to analyse the optimal balance between increasing returns to scale and recombinant innovation it is discussed under which conditions one of four solutions is optimal complete specialization regardless of which option complete specialization in one specific option symmetric diversity perfect balance and asymmetric diversity the results give rise to a number of policy insights

addressing global environmental externalities transaction costs considerations is there a way to understand why some global environmental externalities are addressed effectively whereas others are not the transaction costs of defining the property rights to mitigation benefits and costs is a useful framework for such analysis this approach views international cooperation as a contractual process among country leaders to assign those property rights leaders cooperate when it serves domestic interests to do so the demand for property rights comes from those who value and stand to gain from multilateral action property rights are supplied by international agreements that specify resource access and use assign costs and benefits including outlining the size and duration of compensating transfer payments and determining who will pay and who will receive them four factors raise the transaction costs of assigning property rights i scientific uncertainty regarding mitigation benefits and costs ii varying preferences and perceptions across heterogeneous populations iii asymmetric information and iv the extent of compliance and new entry these factors are used to examine the role of transaction costs in the establishment and allocation of property rights to provide globally valued national parks implement the convention on the international trade in endangered species of wild fauna and flora execute the montreal protocol to manage emissions that damage the stratospheric ozone layer set limits on harvest of highly migratory ocean fish stocks and control greenhouse gas emissions jel d23 p14 q22 q51 q54 q58

investment in risky r d programs in the face of climate uncertainty we analyze how the socially optimal technology rd and that uncertainty in damages interacts with uncertainty in the returns to rd and r d that reduces the emissions to output ratio and argue that this is a good representation of r d into fossil fuel technologies for r d programs into non carbon technologies optimal investment is higher in riskier programs our empirical model indicates that the optimal investment in a risky program is about 3 1 2 times larger than in a program with certain returns for r d programs aimed at reducing emissions in fossil fuel based technologies our results show that qualitatively investment is higher in less risky programs under most uncertain damage scenarios our empirical model shows however that the risk profile of fossil fuel based r d programs generally has little quantitative impact on optimal investment the exception is that when the probability of a catastrophe inducing full abatement is very high investment is about twice as high in risky programs compared to programs with certain returns

spatial renewable resource extraction under possible regime shift how will countries harvesting mobile natural resources react to the possibility of regime shift we address the non cooperative exploitation of a migratory renewable resource in the presence of possible regime shift that affects its movement motivated by the anticipated effects of climate change we model a regime shift that will alter the spatial movement patterns of the resource at some point in the future we develop a stochastic spatial bioeconomic model to address the effects of this class of regime shift on non cooperative harvest decisions made by decentralized owners such as countries exploiting a migratory fish or other natural resource stock we find that the threat of a future shift modies the standard golden rule and may induce more aggressive harvest everywhere irrespective of whether the owner will be advantaged or disadvantaged by the shift we also identify conditions under which the threat of regime shift induces owners to reduce harvest rates in advance of the shift our analysis suggests that different property rights structures single ownership vs common property or heterogeneous growth can give rise to previously unexplored incentives and can even reverse conventional wisdom about how countries will react to the prospect of future environmental change

the stability likelihood of an international climate agreement results derived from empirical analyses on the stability of climate coalitions are usually very sensitive to the large uncertainties associated with the benefits and costs of climate policies this paper provides the methodology of stability likelihood sl that links uncertainties about benefits and costs of climate change to the stability of coalitions we show that the concept of sl improves upon the robustness and interpretation of stability analyses moreover our numerical application qualifies conclusions from a recent strand of literature based on stylised models with ex ante symmetric players that learning has a negative impact on the success of coalition formation in context of uncertainty

uncertainty and climate change uncertainty is pervasive in analysis of climate change how should economists allow for this and how have they allowed for it this paper reviews both of

should we beware of the precautionary principle precautionary principle the economic perspective how should society deal with risks when there is scientific uncertainty about the size of these risks there has been much recent discussion of the precautionary principle which states that lack of full scientific knowledge should not be used as a reason to postpone cost effective preventive measures we show in this paper that the precautionary principle contradicts one important intuition about the right way to act in the face of risk namely the principle of looking before you leap when we expect to learn more about the future the effectiveness of our preventive measures will be greater if we learn before we act however a number of other ways of taking uncertainty into account are consistent with a reasonable interpretation of the precautionary principle first postponing preventive measures may increase our vulnerability to damage which induces a precautionary motive for risk prevention similar to the precautionary savings motive secondly stronger preventive actions often yield more flexibility for the future so that acting early has an option value thirdly when better information comes from a process of learning by doing the risk associated with early events is amplified by the information they yield about the future this plays a role analogous to that of an increase in risk aversion making us more cautious fourthly because imperfect knowledge of the risk makes it difficult to insure the social cost of risk should include a risk premium finally uncertainty about the economic environment enjoyed by future generations should be taken into account this raises the benefit of acting early to prevent long term risks if the precautionary principle sometimes gives good and sometimes gives bad advice there is no escape from the need to undertake a careful cost benefit analysis we show that standard cost benefit analysis can be refined to take account of scientific uncertainty in ways that balance the precautionary principle against the benefits of waiting to learn before we act furthermore it is important that they be used to do so for instinct is an unreliable guide in such circumstances abandoning cost benefit analysis in favour of simple maxims can result in some seriously misleading conclusions christian gollier

climate change environmental and technology policies in a strategic context there are a number of features of climate change which make it one of the most challenging problems confronting policy makers and policy analysts in this paper we consider three such features i climate change is a global pollutant so there are strategic interactions between governments over climate policy ii cutting greenhouse gas emissions can have significant cost effects across a number of sectors of the economy raising concerns about the implications of climate change policy on competitive advantage iii the long time scales on which climate change operates means that an important dimension of climate change policy is policy towards r d to cut the costs of dealing with climate change in ulph and ulph 1996 ulph a ulph d 1996 in carraro c katsoulacos y xepapadeas a eds environmental policy and market structure kluwer dordrecht pp 181 208 we presented a model to analyse these issues but considered only environmental policies in this paper we extend that analysis to allow for both a richer set of policy instruments environmental and technology policies and a richer strategic context

revocability and reversibility in societal decision making abstract reversibility and irreversibility are poorly defined in the decision making literature defining reversibility as the ability to maintain and to restore the functional performance of a system is consistent with thermodynamics specification of its crucial terms is case dependent reversibility is coming in degrees from flexibility over rigidity to preclusion with irreversibility as an absolute end further substantiating reversibility considers three variables duration of impacts revoking costs and substitutability substitutability depends on weights assigned to the strict identity or to the functional performance of something valued for given degrees of substitutability revocability of an action is measurable in time dependent revoking costs together with future time and doubt reversibility sets a three dimensional context for societal decision making revealing domes of expanding complexity cost benefit analysis is a useful decision tool at lower complexity but falters at high complexity because there prevail non monetary trade offs a revival and proper use of the concept reversibility are recommended for improved dialog on major societal issues with climate change outstanding as the case where reversibility could turn into absolute irreversibility also shown is the correspondence between reversibility and ecological concepts like resilience lock in tipping points and others

global warming endogenous risk and irreversibility this paper develops two period analytical and numerical models to study the question given a stock of greenhouse gases that poses a risk of future damages of unknown magnitude and the possibility of learning about damages how do sunk abatement capital and a nondegradable stock of greenhouse gases affect optimal first period investment we show that both affect investment the former negatively and the latter positively additionally endogenous risk the risk of damages dependent on the stock of gases results in an increase in optimal investment for any level of capital sunkness or greenhouse gas degradability quantitatively the effect of sunk capital is stronger than the effect of greenhouse gas irreversibility or that of endogenous risk

experimentation with accumulation abstract we study signal dependent experimentation in the presence of accumulation and show that the passive learner s action surprisingly coincides with the experimentor s when the unknown term is the one determining the decay rate of the stock while they differ when the parameter being learned is the one measuring the accumulation rate these results highlight the importance of the dynamic structure of the problem in signal dependent experimentation moreover they have important consequences for the pollution accumulation debate currently in progress

scientific progress and irreversibility an economic interpretation of the precautionary principle abstract we consider the problem of the optimal use of a good whose consumption can produce damages in the future scientific progress is made over time that provides information on the distribution of the intensity of damages we show that this progress induces earlier prevention effort only if prudence is larger than twice absolute risk aversion this paper thus identifies the class of quite restrictive but plausible conditions such that scientific uncertainties justify an immediate reduction of the consumption of a potentially toxic substance

strategic information acquisition and the mitigation of global warming abstract we consider the strategic role of uncertainty and information acquisition for the mitigation of global warming before the countries decide on their contribution to a mitigation of global warming they may invest in information about the country specific benefit of reductions of the emissions of greenhouse gases we show that information acquisition has a substantial strategic value countries may prefer not to learn their benefit of climate protection even if information acquisition does not involve a direct cost this strategic information choice may further decrease the efficiency of the public good provision

specifications of social welfare in economic studies of climate policy overview of criteria and related policy insights an important assumption in economic studies of climate policy is the social welfare function this paper shows that applying distinct decision or social welfare criteria can result in different optimal policies of climate control notably if climate change impacts are uncertain first decision criteria in current climate economic studies are reviewed next the most important alternatives are discussed including their mathematical formalization and incorporation in economy climate models most of these alternative criteria suggest more stringent climate policies to be optimal than the standard discounted utilitarianism approach however several important welfare criteria have not or hardly seen any application in the economic analysis of climate policy we conclude that there is clear need for systematic research on this theme for which the current review provides a solid basis

taking one for the team is collective action more responsive to ecological change debate persists around the timing of risk reduction strategies for large scale ecological change for three reasons risks are difficult to predict they involve irreversibilities and they impact multiple jurisdictions the combination of these three factors creates a general class of filterable spatial dynamic externalities fsde in which one person s risk reduction investments reduce or filter undesirable events experienced by others and underestimates the option value placed on being able to respond to new information about the consequences of ecological change by focusing on the optimal intervention decision we illustrate how and when the opposing forces created by an fsde will lead to a divergence in private and collective risk reduction strategies we use bioinvasions as our motivating example the bioinvasion first hits one jurisdiction and that jurisdiction s risk reduction investment reduces the risk faced by all other jurisdiction we find that efforts to internalize the full benefits of risk reduction investments may have unintended consequences on the responsiveness of environmental policy there is a social welfare gain from asking the first jurisdiction to delay a risk reduction investment to internalize the option values of all at risk jurisdictions

policy experimentation political competition and heterogeneous beliefs abstract we consider a two period model in which an incumbent political party chooses the level of a current policy variable unilaterally but faces competition from a political opponent in the future both parties care about voters payoffs but they have different beliefs about how policy choices will map into future economic outcomes we show that when the incumbent party can endogenously influence whether learning occurs through its policy choices policy experimentation future political competition gives it a new incentive to distort its policies it manipulates them so as to reduce uncertainty and disagreement in the future thus avoiding facing competitive elections with an opponent very different from itself the model thus demonstrates that all incumbents can find it optimal to over experiment relative to a counterfactual in which they are sure to be in power in both periods we thus identify an incentive for strategic policy manipulation that does not depend on parties having conflicting objectives but rather stems from their differing beliefs about the consequences of their actions

energy transition under irreversibility a two sector approach in this paper we analyze the optimal energy transition of a two sector economy energy and final goods with exhaustible oil reserves a renewable source of energy and a pollution threat the latter corresponds to a pollution threshold above which a part of the capital is lost following flooding for instance we show that the optimal energy transition path may correspond to a corner regime in which the economy starts using both resources then crosses the pollution threshold and therefore loses a part of its capital at the end the sole adoption of the renewable energy is optimal only in the long run this result is in line with the asymptotic energy transition arguments stating that the transition to clean energy may happen only in the long run we also show that economy reduces the use of energy resource as long as the productivity of capital and energy services is high therefore public policies should promote investments in energy innovation that targets productive sector home appliances and buildings and helps to save both money and energy we extend the present model to allow for additional investment in energy saving technologies our main results show that this additional investment favours the energy transition in the sense that it increases the time within which the economy may experience the catastrophe and the welfare of the society for policy implications economic instruments such as taxes on dirty energy subsidies on clean energy or incentives for energy saving technologies need to be implemented in order to promote the energy transition this is particularly important for developing countries that mostly rely on polluting energy resources and are the most vulnerable to climate change but those economic instruments should be carefully designed in line with the asymptotic energy transition result

uncertainty learning and international environmental agreements the role of risk aversion this paper analyses the formation of international environmental agreements ieas under uncertainty learning and risk aversion it bridges two strands of the iea literature i the role of learning when countries are risk neutral ii the role of risk aversion under no learning combining learning and risk aversion seems appropriate as the uncertainties surrounding many international environmental problems are large often highly correlated e g climate change but are gradually reduced over time through learning the paper analyses three scenarios of learning a key finding is that risk aversion can change the ranking of these three scenarios of learning in terms of welfare and membership in particular the negative conclusion about the role of learning in a strategic context under risk neutrality is qualified when countries are significantly risk averse then it pays them to wait until uncertainties have been largely resolved before joining an iea this may suggest why it has been so difficult to reach an effective climate change agreement

the climate change learning curve abstract the purpose of this paper is to confront economic models of climate change with the reality that limited information exists with which to form expectations about the evolution of the climate a key element in the tension between those who believe we should impose aggressive climate change mitigation policies and those who do not is the question of if we are merely in a long period of shock induced above average temperatures or if observed increases in temperature are a result of carbon emissions this paper characterizes learning dynamics resulting from the use of observations of temperature to update beliefs about two key characteristics of global climate the persistence of natural trends and the sensitivity of temperature to atmospheric carbon levels this paper shows that contrary to predictions in the literature that uncertainty may be resolved very quickly the time to learn the true processes may be in the order of thousands of years further this paper shows the effects of uncertainty on the likelihood that observations from the statistical record lead to important estimate and policy errors

using fast and slow processes to manage resources with thresholds economists have relied on convexity assumptions for a long time but many natural resources that stem from ecosystems have non convexities in their dynamics this article illustrates the consequences of relaxing convexity assumptions for management and the role of fast and slow variables the paper presents a general framework to handle systems with fast and slow variables and illustrates the method using a model of coral reefs subject to fishing pressure the insights obtained are used to discuss alternative management strategies