endogenous growth convexity of damage and climate risk how nordhaus framework supports deep cuts in carbon emissions to slow or not to slow nordhaus 1991 was the first economic appraisal of greenhouse gas emissions abatement and founded a large literature on a topic of worldwide importance we offer our assessment of the original article and trace its legacy in particular nordhaus s later series of dice models from this work many have drawn the conclusion that an efficient global emissions abatement policy comprises modest and modestly increasing controls we use dice itself to provide an initial illustration that if the analysis is extended to take more strongly into account three essential elements of the climate problem the endogeneity of growth the convexity of damage and climate risk optimal policy comprises strong controls

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

corporate social responsibility for supply chain management a literature review and bibliometric analysis corporate social responsibility csr in supply chain management scm has gained an increasing research attention in recent years extant studies have discussed stakeholder interests performance evaluation ethical sourcing and sustainable production the purpose of this paper is to develop a systematic study quantitatively depicting the knowledge structure and the intellectual progress of csr for scm this research adopts bibliometric analysis in conjunction with network analysis to systematically evaluate the csr related publications for scm the analysis involves 628 peer reviewed articles identified with careful selection of influential work data analytic techniques including citation analysis co citation analysis and co word analysis are used key findings for researchers include 1 an analytical discussion of the five sub fields that constitute the intellectual structure of csr for scm 2 theoretical and conceptual research significantly dominate in this field 3 the topics of sustainable development and economic and social effects are more frequently discussed among scholars 4 key research gaps include lacking of practical and normative modeling research and considering from the supplier perspectives in emerging economies the findings suggest that future research would emerge a greater depth of practical and modeling analysis to enrich the theories

scientific ambiguity and climate policy economic evaluation of climate policy traditionally treats uncertainty by appealing to expected utility theory yet our knowledge of the impacts of climate policy may not be of sufficient quality to be described by unique probabilistic beliefs in such circumstances it has been argued that the axioms of expected utility theory may not be the correct standard of rationality by contrast several axiomatic frameworks have recently been proposed that account for ambiguous knowledge in this paper we apply static and dynamic versions of a smooth ambiguity model to climate mitigation policy we obtain a general result on the comparative statics of optimal abatement and ambiguity aversion and then extend our analysis to a more realistic dynamic setting where we introduce scientific ambiguity into the well known dice model of the climate economy system for policy relevant exogenous mitigation policies we show that the value of emissions abatement increases as ambiguity aversion increases and that this ambiguity premium can in some plausible cases be very large in these cases the effect of ambiguity aversion on welfare is comparable to that of other much studied welfare parameters thus ambiguity aversion may be an important neglected aspect of climate change economics and seems likely to provide another argument for strong abatement policy

fat tails exponents extreme uncertainty simulating catastrophe in dice abstract the problem of low probability catastrophic risk is increasingly central to discussion of climate science and policy but the integrated assessment models iams of climate economics rarely incorporate this possibility what modifications are needed to analyze catastrophic economic risks in an iam we explore this question using dice a well known iam we examine the implications of a fat tailed probability distribution for the climate sensitivity parameter a focus of recent work by martin weitzman and the shape of the damage function one of the issues raised by the stern review forecasts of disastrous economic outcomes in dice can result from the interaction of these two innovations but not from either one alone

climate change policy under polar amplification abstract polar amplification is an established scientific fact which has been associated with the surface albedo feedback and with heat and moisture transport from the equator to the poles in this paper we unify a two box climate model which allows for heat and moisture transport from the southern region to the northern region with an economic model of welfare optimization our main contribution is to show that by ignoring spatial heat and moisture transport and the resulting polar amplification the regulator may overestimate or underestimate the tax on greenhouse gas emissions the direction of bias depends on the relations between marginal damages from temperature increase in each region we also determine the welfare cost when a regulator mistakenly ignores polar amplification numerical simulations confirm our theoretical results while ballpark estimates indicate that the tax bias could be as high as 20 while welfare cost could reach 2 of global effective steady state consumption

rationalizing hyperbolic discounting abstract we show that if agents are uncertain about their discount rates it may be rational for them to discount the distant future hyperbolically rather than exponentially our findings thus may rationalize a common observation in experimental work which indicates that people discount the future at hyperbolic rates we show that under some assumptions uncertainty over hazard rates may lead to non constant discounting but not imply dynamically inconsistent behavior under other assumptions uncertainty over discount rates can lead to dynamically inconsistent behavior like violating planned consumption profiles by bringing consumption forward

asymmetric effects of the business cycle on carbon dioxide emissions abstract long term carbon dioxide emissions forecasts rely on the assumption that the economic growth rate is constant over long time horizons and exclude the business cycle thereby ignoring a fundamental component of the macroeconomy this paper considers how the business cycle affects emissions forecasts and shows the implicit assumption in current forecasts that the elasticity of emissions is constant with respect to gdp is wrong in the united states emissions fall more sharply when gdp declines than they rise when gdp increases this is partly due to a decrease in industrial energy intensity as gdp declines a simulation shows that accounting for the business cycle results in 5 lower cumulative emissions through 2050 relative to the baseline forecast

risk aversion intergenerational equity and climate change the paper investigates a climate economy model with an iso elastic welfare function in which one parameter measures relative risk aversion and a distinct parameter measures resistance to intertemporal substitution we show both theoretically and numerically that climate policy responds differently to variations in the two parameters in particular we show that higher but lower leads to increase emissions control we also argue that climate economy models based on intertemporal expected utility maximization i e models where may misinterpret the sensitivity of the climate policy to risk aversion

on decomposing the wage gap a critical comment on blinder s method many studies have found that the impact of schooling on earnings is greater for females than for males despite the fact that females tend to earn less both absolutely and controlling for personal characteristics this study investigates possible

inter linking issues and dimensions in sustainability reporting during the last decade sustainability reporting sr has been increasingly adopted by corporations worldwide this is evidenced by the adoption of several guidelines such as the iso 14000 series the social accountability 8000 standard and the gri sustainability guidelines sr shows promise to help corporate leaders and their employees to contribute towards achieving sustainable societies however most of the guidelines and standards address sustainability issues through comparmentalisation thereby leading to the separation of the economic environmental and social dimensions due to these divisive approaches holistic assessments of the effects of their efforts are seldom properly integrated into coporate decisions and procedures to make improvements for example through cleaner production worker health and safety consumer safety and reductions in the negative short and long term social and environmental impacts this paper analyses sr reports from three companies with the help of grounded theory s constant comparative analysis this analytical framework helped the authors to systematically assess the degree to which the companies addressed economic ecological and social issues separately or in an integrated and inter linked manner from the inter linkages found a new category is proposed to be added to future sr this new category can help corporate sr planners and researchers on sustainability reports to better understand how the company leaders understand their responsibilities with regard to sd these inter connectednesses are highly relevant in many short and long term dimensions of supply chain management global warming ecological disruption and societal equity issues especially with regard to the local national and global energy issues of fuels and oils the central themes of the conference at which this paper was originally presented it also plays a key role in real long term changes towards sustainability where the time dimension plays a key role in human survival on planet earth

carbon pricing carbon sequestration and social discounting abstract this paper studies the optimal taxation of carbon emissions in a dynastic economy when the welfare function places direct pareto weights on unborn generations the social discount rate is lower than the discount rate of the current generation i show that this welfare criterion has important consequences for the structure of the optimal regulatory system in particular i show that i the optimal carbon tax does not in general equal the social cost of carbon ii a subsidy on oil reserves is sometimes optimal and iii carbon trading programs should limit the award of carbon offset allowances

supply chain specific understanding the patchy success of ethical sourcing initiatives as a number of high profile companies have found to their cost corporate reputations can be significantly affected by firms management of sustainability issue including those that are outside their direct control such as the environmental and social impacts of their supply networks this paper begins by examining the relationship between corporate social responsibility reputation and supply network conditions it then looks at the effectiveness of one tool for managing supply network sustainability issues ethical sourcing codes of conduct by examining how the characteristics of three supply networks branded clothes diy wood products and branded confectionary affects the implementation ethical sourcing codes of conduct it ends by setting out conclusions on why implementation of such codes has been so much more successful in some sectors than others and recommendations on effective approaches to managing sustainability issues in supply networks

economic growth effects of alternative climate change impact channels in economic modeling despite increasing empirical evidence of strong links between climate and economic growth there is no established model to describe the dynamics of how different types of climate shocks affect growth patterns here we present the first comprehensive comparative analysis of the long term dynamics of one time temporary climate shocks on production factors and factor productivity respectively in a ramsey type growth model damages acting directly on production factors allow us to study dynamic effects on factor allocation savings and economic growth we find that the persistence of impacts on economic activity is smallest for climate shocks directly impacting output and successively increases for direct damages on capital loss of labor and productivity shocks related to different responses in savings rates and factor specific growth recurring shocks lead to large welfare effects and long term growth effects directly linked to the persistence of individual shocks endogenous savings and shock anticipation both have adaptive effects but do not eliminate differences between impact channels or significantly lower the dissipation time accounting for endogenous growth mechanisms increases the effects we also find strong effects on income shares important for distributional implications this work fosters conceptual understanding of impact dynamics in growth models opening options for links to empirics

the agnostic s response to climate deniers price carbon with the election of president trump climate deniers feel emboldened and moved from the fringes to the centre of global policy making we study how an agnostic approach to policy based on pascal s wager and allowing for subjective prior probability beliefs about whether climate deniers are right prices carbon using the dice integrated assessment model we find that assigning a 10 chance of climate deniers being correct lowers the global price on carbon in 2020 only marginally from 21 to 19 per ton of carbon dioxide if policymakers apply nordhaus discounting and from 91 to 84 per ton of carbon dioxide if they apply stern discounting agnostics reflection of remaining scientific uncertainty leaves climate policy essentially unchanged the robustness of an ambitious climate policy also follows from using the max min or the min max regret principle letting the coefficient of relative ambiguity aversion vary from zero corresponding to expected utility analysis to infinity corresponding to the max min principle we show how policy makers deal with fundamental climate model uncertainty if they are prepared to assign prior probabilities to different views of the world being correct allowing for an ethical discount rate and a higher market discount rate and for a wide range of sensitivity exercises including damage uncertainty we show that pricing carbon is the robust response under rising climate scepticism

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

why the far distant future should be discounted at its lowest possible rate abstract a critical feature of the distant future is currently unresolvable uncertainty about what will then be the appropriate rate of return on capital to use for discounting this paper shows that there is a well defined sense in which the lowest possible interest rate should be used for discounting the far distant future part of any investment project some implications are discussed for evaluating long term environmental projects or activities like measures to mitigate the possible effects of global climate change

male female earnings differentials in malaysia empirical studies on male female earnings differentials in asian ldcs are few and far between this study finds that differences in productive endowments account for only about 54 per cent of the monthly earnings differential in malaysia the major part of this difference may be attributable to a more favourable occupational distribution among males overall females tend to be concentrated in subordinate occupations and appear to be paid less for similar human capital endowments

learning and climate feedbacks optimal climate insurance and fat tails we study the effect of potentially severe climate change on optimal climate change policy accounting for learning and uncertainty in the climate system in particular we test how fat upper tailed uncertainty over the temperature change from a doubling of greenhouse gases the climate sensitivity affects economic growth and emissions policy in addition we examine whether and how fast uncertainties could be diminished through bayesian learning our results indicate that while overall learning is slow the mass of the fat tail diminishes quickly since observations near the mean provide evidence against fat tails we denote as partial learning the case where the planner rejects high values of the climate sensitivity with high confidence even though significant uncertainty remains fat tailed uncertainty without learning reduces current emissions by 38 relative to certainty indicating significant climate insurance or paying to limit emissions today to reduce the risk of very high temperature changes is optimal however learning reduces climate insurance by about 50 the optimal abatement policy is strongly influenced by the current state of knowledge even though greenhouse gas ghg emissions are difficult to reverse non fat tailed uncertainty is largely irrelevant for optimal emissions policy

abrupt positive feedback and the social cost of carbon optimal climate policy should act in a precautionary fashion to deal with tipping points that occur at some future random moment the optimal carbon tax should include an additional component on top of the conventional present discounted value of marginal global warming damages this component increases with the sensitivity of the hazard to temperature or the stock of atmospheric carbon if the hazard of a catastrophe is constant no correction is needed of the usual pigouvian tax the results are applied to a tipping point resulting from an abrupt and irreversible release of greenhouse gases from the ocean floors and surface of the earth which set in motion a positive feedback loop convex enough hazard functions cause overshooting of the carbon tax but a linear hazard function gives rise to undershooting a more convex hazard function and a high discount rate speed up adjustment

consumption pollution tradeoffs in an environment vulnerable to pollution related catastrophic collapse abstract this paper considers the consequences of an avoidable risk of irreversible environmental catastrophe for society s optimal long run consumption pollution tradeoffs the risk is assumed to be a nondecreasing function of pollution concentration which evolves as a dynamic environmental renewal process the main objective of the paper is to derive qualitative insights regarding the effects of such risk on optimal management

pricing uncertainty induced by climate change geophysicists examine and document the repercussions for the earth s climate induced by alternative emission scenarios and model specifications using simplified approximations they produce tractable characterizations of the associated uncertainty meanwhile economists write highly stylized damage functions to speculate about how climate change alters macroeconomic and growth opportunities how can we assess both climate and emissions impacts as well as uncertainty in the broadest sense in social decision making we provide a framework for answering this question by embracing recent decision theory and tools from asset pricing and we apply this structure with its interacting components to a revealing quantitative illustration

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

climate tipping and economic growth precautionary capital and the price of carbon the optimal reaction to a climate tipping point that becomes more imminent with global warming is to be precautionary in adjusting capital to prepare for the calamity and to price carbon to make catastrophic change less imminent the saving response can be positive or negative if the mean lag for the impact of the catastrophe is long enough the saving response will be negative because the precautionary return in the keynes ramsey rule becomes negative we also show the separate effects of the elasticity of intertemporal substitution eis and the relative risk aversion rra using duffie epstein preferences focusing on a productivity catastrophe we calibrate our model and show how sensitive the policy responses are to the degrees of eis and rra the trend rate of economic growth the hazard rate and how long it takes for the catastrophe to have its full impact

determining the social cost of carbon under damage and climate sensitivity uncertainty this article quantifies the impact on optimal climate policy of both damage elasticity and equilibrium climate sensitivity uncertainty under separable preferences for risk and intergenerational inequality the primary findings are as follows 1 such preferences can depress the social cost of carbon scc when calibration aims at matching actual economic outcomes countering the prevailing view that the scc is greater with separable than with conventional entangled preferences 2 damage elasticity uncertainty has larger effects on climate policy than equilibrium climate sensitivity uncertainty even under high impact tail risk of the latter 3 risk aversion decisively strengthens optimal climate policy under joint damage and climate sensitivity uncertainty than with a single source of uncertainty alone indeed failing to account for the interaction between damage and climate sensitivity uncertainty underestimates the cost of climate change by more than us dollars 1 trillion

uncertainty of climate policies and implications for economics and finance an evolutionary economics approach the assessment of the socio economic and financial impacts of climate change represents a main source of uncertainty for policy makers and investors however traditional climate economics and financial risk models are not properly equipped to consider the characteristics of climate risks and the opportunities from climate alignment being constrained by equilibrium conditions and linearity of impacts as well as by representative agents and intertemporal optimization given the closing window of opportunity to achieve the 2 c target there is an urgent need for a new wave of models able to embrace uncertainty and complexity deriving not only from climate impacts on socio economic systems but also from their reaction in this regard approaches rooted on evolutionary economics and complexity science could provide complementary insights to traditional climate economics models this special issue contributes to fill in this knowledge gap by collecting nine papers applying evolutionary and complex systems approaches and agent based and network models to climate change economics presented at the special session of the research area environment economics interactions of the european association of evolutionary political economy eaepe s conference 2016 by introducing conceptual and methodological innovations in climate economics and finance the nine articles analyse the conditions for effective climate policies and financial instruments to align countries to the global climate targets compared to the costs of inaction this information is crucial to support decision makers in the analysis of climate finance policies and instruments to foster the transition to a sustainable and inclusive low carbon economy

accounting for global warming risks resource management under event uncertainty abstract optimal management of atmospheric pollution is discussed with a special emphasis on the uncertainty concerning the occurrence of undesirable events associated with the greenhouse effect the uncertainty considered here stems from our ignorance of the exact pollution level required to trigger the event rather than from the genuinely stochastic nature of the processes involved taking atmospheric pollution level as the state variable it is found that uncertainty implies the existence of an equilibrium interval within which the emission rate of the greenhouse gases should be kept equal to the natural removal rate of these gases processes initiated outside the equilibrium interval must converge monotonically to its nearest endpoint the determination of the interval requires no knowledge of the optimal policy in contrast ignoring event occurrence risk implies a single equilibrium level attracting the optimal process from any initial level

carbon prices for the next hundred years this paper examines the socially optimal pricing of carbon emissions over time when climate change impacts are unknown potentially high consequence events the carbon price tends to increase with income but learning about impacts or their absence decouples the carbon price from income growth the price should grow faster than the economy if the past warming is not substantial enough for learning the true long run social cost it grows slower than the economy as soon as the warming generates information about events that could have arrived but have not done so a quantitative assessment shows that the price grows roughly at the rate of the economy for the next 100 years

discounting the distant future how much do uncertain rates increase valuations abstract we demonstrate that when the future path of the discount rate is uncertain and highly correlated the distant future should be discounted at significantly lower rates than suggested by the current rate we then use two centuries of us interest rate data to quantify this effect using both random walk and mean reverting models we compute the certainty equivalent rate that summarizes the effect of uncertainty and measures the appropriate forward rate of discount in the future under the random walk model we find that the certainty equivalent rate falls continuously from 4 to 2 after 100 years 1 after 200 years and 0 5 after 300 years at horizons of 400 years the discounted value increases by a factor of over 40 000 relative to conventional discounting applied to climate change mitigation we find that incorporating discount rate uncertainty almost doubles the expected present value of mitigation benefits

optimal taxes on fossil fuel in general equilibrium we analyze a dynamic stochastic general equilibrium dsge model with an externality through climate change from using fossil energy our central result is a simple formula for the marginal externality damage of emissions or equivalently for the optimal carbon tax this formula which holds under quite plausible assumptions reveals that the damage is proportional to current gdp with the proportion depending only on three factors i discounting ii the expected damage elasticity how many percent of the output flow is lost from an extra unit of carbon in the atmosphere and iii the structure of carbon depreciation in the atmosphere thus the stochastic values of future output consumption and the atmospheric co2 concentration as well as the paths of technology whether endogenous or exogenous and population and so on all disappear from the formula we find that the optimal tax should be a bit higher than the median or most well known estimates in the literature we also formulate a parsimonious yet comprehensive and easily solved model allowing us to compute the optimal and market paths for the use of different sources of energy and the corresponding climate change we find coal rather than oil to be the main threat to economic welfare largely due to its abundance we also find that the costs of inaction are particularly sensitive to the assumptions regarding the substitutability of different energy sources and technological progress

women wages and discrimination some evidence from taiwan in 1982 male employees in taiwan earned an average monthly salary of nt 11 008 us 275 women earned under two thirds of this at nt 7 087 this paper examines whether the male female earnings differential in taiwan can be explained by different endowments between the sexes of productivity related characteristics such as education and work experience if men and women are paid according to the same wage structure different endowments will account for all the observed earnings differential any wage gap that remains as a residual after adjustment for endowments can be interpreted as evidence of wage discrimination between the sexes following the work of oaxaca and malkiel and malkiel there is now a large number of american studies that use human capital theory as the basis for decomposing sex specific earnings into an endowment component and a discrimination component estimates also exist for canada and britain 2 house in his calculations for cyprus has provided the first estimates for a developing country 3 a case study for taiwan is particularly interesting not only because of the role of female employment in taiwan s industrial growth but also because the quality of the data makes possible a sharper test of discrimination than most other studies

a 4 stated dice quantitatively addressing uncertainty effects in climate change we introduce a version of the dice 2007 model designed for uncertainty analysis dice is a wide spread deterministic integrated assessment model of climate change climate change long term economic development and their interactions are highly uncertain the quantitative analysis of optimal mitigation policy under uncertainty requires a recursive dynamic programming implementation of integrated assessment models such implementations are subject to the curse of dimensionality every increase in the dimension of the state space is paid for by a combination of exponentially increasing processor time lower quality of the value or policy function approximations and reductions of the uncertainty domain the paper promotes a state reduced recursive dynamic programming implementation of the dice 2007 model we achieve the reduction by simplifying the carbon cycle and the temperature delay equations we compare our model s performance and that of the dice model to the scientific aogcm models emulated by magicc 6 0 and find that our simplified model performs equally well as the original dice model our implementation solves the infinite planning horizon problem in an arbitrary time step the paper is the first to carefully analyze the quality of the value function approximation using two different types of basis functions and systematically varying the dimension of the basis we present the closed form continuous time approximation to the exogenous discretely and inductively defined processes in dice and we present a numerically more efficient re normalized bellman equation that in addition can disentangle risk attitude from the propensity to smooth consumption over time

be careful what you calibrate for social discounting in general equilibrium abstract concerns about intergenerational equity have led to an influential practice of setting social utility discount rates based on ethical considerations rather than to match household behavior particularly in climate change economics e g stern 2006 this paper formalizes the broader policy implications of this approach in general equilibrium by characterizing jointly optimal environmental and fiscal policies in a climate economy model with differential planner household discounting first i show that decentralizing the optimal allocation requires not only high carbon prices but also fundamental changes to tax policy if the government discounts the future less than households implementing the optimal allocation requires an effective capital income subsidy a negative intertemporal wedge and in a setting with distortionary taxation an effective labor consumption tax wedge that is decreasing over time second if the government cannot subsidize capital income the constrained optimal carbon tax may be up to 50 below the present value of marginal damages the social cost of carbon due to the general equilibrium effects of climate policy on household savings third given the choice to optimize either carbon capital or labor income taxes the socially discounting planner s welfare ranking is ambiguous over a standard range of parameters overall in general equilibrium a policy maker s choice to adopt differential social discounting may thus overturn conventional recommendations for both environmental and fiscal policy

gender differences in observed and offered wages in canada 1980 according to the 1981 census of canada the female rate of pay is 30 percent less than the male rate the average female wage offer however is only around one half of that received by males other things being equal slightly more than one half of the difference in observed wages can be explained by diffe rences in wage related characteristics between males and females two fifths of the disparity between wage offers can be explained by the same set of factors analysis of the distribution of wage offers indicates greater wage inequality in the canadian labor market than suggested by study of observed wages

optimal management with potential regime shifts we analyze how the threat of a potential future regime shift affects optimal management we use a simple general growth model to analyze four cases that involve combinations of stock collapse versus changes in system dynamics and exogenous versus endogenous probabilities of regime shift prior work in economics has focused on stock collapse with endogenous probabilities and reaches ambiguous conclusions on whether the potential for regime shift will increase or decrease intensity of resource use and level of resource stock we show that all other cases yield unambiguous results in particular with endogenous probability of regime shift that affects system dynamics the potential for regime shift causes optimal management to become precautionary in the sense of maintaining higher resource stock levels

taxes and quotas for a stock pollutant with multiplicative uncertainty we compare taxes and quotas when firms and the regulator have asymmetric information about the slope of firms abatement costs damages are caused by a stock pollutant we calibrate the model using cost and damage estimates of greenhouse gasses taxes dominate quotas as with additive uncertainty this model with multiplicative uncertainty allows us to compare expected stock levels under the two policies and to investigate the importance of stock size and the magnitude of uncertainty on the policy ranking

emissions targets and the real business cycle intensity targets versus caps or taxes for reducing greenhouse gas emissions intensity targets are attracting interest as a flexible mechanism that would better allow for economic growth than emissions caps for the same expected emissions however the economic responses to unexpected productivity shocks differ using a real business cycle model we find that a cap dampens the effects of productivity shocks in the economy on all variables except for the shadow value of the emissions constraint an emissions tax leads to the same expected outcomes as a cap but with greater volatility certainty equivalent intensity targets maintain higher levels of labor capital and output than other policies with lower expected costs and no more volatility than with no policy

sex differences in earnings an analysis of malaysian wage data the conventional human capital earnings function is applied to a rich set of malaysian wage data in an attempt to determine the origins of sex differences in average earnings several findings are of interest the first being that the relationships estimated from the earnings function are similar to those typically reported for non ldcs second less than a third of the average monthly wage difference between the sexes of about 34 per cent appears to be the consequence of either females having lower measured productivity than males or females receiving lower rates of return to human capital than males the major part of the earnings difference is apparently a consequence of employment distributions females are much more likely to be in the low paying occupations

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

the nobel memorial prize for william d nordhaus william d nordhaus and paul m romer received the 2018 sveriges riksbank prize in economic sciences in memory of alfred nobel this paper surveys nordhaus contributions on integrating climate change into long run macroeconomic analysis for which he was recognized with this prize

bayesian learning growth and pollution abstract environmental problems such as climate change have great uncertainties current expectations are that uncertainties about climate change will be resolved quickly we examine this hypothesis theoretically and computationally we consider bayesian learning about the relationship between greenhouse gas levels and global mean temperature changes a key uncertainty learning is non trivial because of a stochastic shock to the realized temperature we find theoretically the expected learning time which is related to the variance of the shock and the emissions policy implying a tradeoff between the benefits of controlling emissions and information we imbed the learning model into an optimal growth model with a climate sector and solve the resulting dynamic program we find computationally that learning takes on average over 90 yr far longer than currently believed

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

the impact of climate change on the balanced growth equivalent an application of fund the stern review added balanced growth equivalents bge to the economic climate change research agenda we first propose rigorous definitions of the bge for multiple regions and under uncertainty we show that the change in the bge is independent of the assumed scenario of per capita income for comparable welfare economic assumptions as the stern review we calculate lower changes in bge between a business as usual scenario and one without climate impacts with the model fund than the stern review found with the model page we find that mitigation policies give even lower changes in bge and argue that those policy choices should be the focus of the research effort rather than total damage estimates according to our results the current carbon tax should be below 55 tc sensitivity analyses show that the stern review chose parameters that imply high impact estimates however for regionally disaggregated welfare functions we find changes in bge that are significantly higher than the results from the stern review both for total damage as for policy analysis with regional disaggregation and high risk aversion we observe fat tails and with that very high welfare losses

a review of the stern review on the economics of climate change how much and how fast should we react to the threat of global warming the stern review argues that the damages from climate change are large and that nations should undertake sharp and immediate reductions in greenhouse gas emissions an examination of the review s radical revision of the economics of climate change finds however that it depends decisively on the assumption of a near zero time discount rate combined with a specific utility function the review s unambiguous conclusions about the need for extreme immediate action will not survive the substitution of assumptions that are consistent with today s marketplace real interest rates and savings rates

assessing social risks of global supply chains a quantitative analytical approach and its application to supplier selection in the german automotive industry abstract risk management in supply chains has gained increasing attention over the last years at the same time the pressure to consider social issues in global and interconnected supply chains has risen as well these issues pose risk to supply chains since their occurrence may cause adverse stakeholder reaction through e g reputational losses despite the growing importance of supplier management as a key process within supply chains and the frequently articulated demand for a quantitative assessment of associated risks such approaches are missing so far thus the aim of this paper is to develop a model to efficiently estimate and assess social risks along global supply chains for this purpose leontief s input output model is combined with country risks and sector specific labour intensities in addition a fuzzy analytical hierarchy process is used to weigh the various considered social risks thereby the focus is on the upstream supply chain of actors in a supply chain the approach is developed generally opening the possibility of adaption to different types of input output data bases and using different social risks discussed in social life cycle assessment the fuzzy analytical hierarchy process facilitates the operational application in companies where different people with differing preferences are involved e g in procurement decisions the model is applied to a case study of a german premium car manufacturer to demonstrate and validate the approach it is shown how based on the developed model the assessment of supply chains risks can be carried out the approach allows an assessment of the supply chain as a whole i e considering all upstream tiers and of specific tiers furthermore a sensitivity analysis with regard to the obtained weights is conducted to verify the final aggregative risk values the results show that there are huge differences in the social risks associated with different suppliers as well as different risk structures along the n tier chain this helps prioritizing any projects with the aim to improve the living and working conditions in summary the model has a great benefit for practitioners in purchasing functions of focal companies and can be a helpful tool to support the efficient handling of social issues along supply chains at the same time its academic contributions lie in extending the life cycle sustainability analysis through a multi regional socially extended input output model seio for social risk assessment in sustainable supply chain management

optimal climate change mitigation under long term growth uncertainty stochastic integrated assessment and analytic findings abstract economic growth over the coming centuries is one of the major determinants of today s optimal greenhouse gas mitigation policy at the same time long run economic growth is highly uncertain this paper is the first to evaluate optimal mitigation policy under long term growth uncertainty in a stochastic integrated assessment model of climate change the sign and magnitude of the impact depend on preference characteristics and on how damages scale with production we explain the different mechanisms driving optimal mitigation under certain growth under uncertain technological progress in the discounted expected utility model and under uncertain technological progress in a more comprehensive asset pricing model based on epstein zin weil preferences in the latter framework the dominating uncertainty impact has the opposite sign of a deterministic growth impact the sign switch results from an endogenous pessimism weighting all of our numeric scenarios use a dice based assessment model and find a higher optimal carbon tax than the deterministic dice base case calibration

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

regulating environmental threats environmental consequences of natural resource exploitation often entail threats of future occurrences of detrimental abrupt events rather than or in addition to inflicting a damage gradually the possibility of abrupt occurrence of climate change related calamities is a case in mind the uncertainty associated with the realization of these threats and their public bad nature complicate the design of optimal economic response we derive a pigouvian hazard tax schedule that implements the socially optimal outcome the tax is based on the expected cost of the hazard generating activities and serves to reduce hazardous emissions well in advance of the catastrophic occurrence a numerical example illustrates possible effects of the proposed regulation scheme implications for climate policy are discussed

on modeling and interpreting the economics of catastrophic climate change with climate change as prototype example this paper analyzes the implications of structural uncertainty for the economics of low probability high impact catastrophes even when updated by bayesian learning uncertain structural parameters induce a critical tail fattening of posterior predictive distributions such fattened tails have strong im plications for situations like climate change where a catastrophe is theoretically possible because prior knowledge cannot place sufficiently narrow bounds on overall damages this paper shows that the economic consequences of fat tailed structural uncertainty along with unsureness about high temperature damages can readily outweigh the effects of discounting in climate change policy analysis

regime shifts and uncertainty in pollution control we develop a simple model of managing a system subject to pollution damage such as climate change under the risk of an abrupt and random jump in the damage function the model allows the full dynamic characterization of the optimal emission policies under uncertainty the results imply precautionary behavior in contrast with the ambiguous outcomes reported in the literature for models of catastrophic occurrences the framework is used to analyze the adaptation vs mitigation dilemma and provides a simple criterion to determine when adaptation activities should be undertaken

precautionary saving in the small and in the large the theory of precautionary saving is shown to be isomorphic to the arrow pratt theory of risk aversion making possible the application of a large body of knowledge about risk aversion to precautionary saving and more generally to the theory of optimal choice under risk in particular a measure of the strength of the precautionary saving motive analogous to the arrow pratt measure of risk aversion is used to establish a number of new propositions about precautionary saving and to give a new interpretation of the dreze modigliani substitution effect copyright 1990 by the econometric society

time perspective and climate change policy the tendency to foreshorten time units as we peer further into the future provides an explanation for hyperbolic discounting at an inter generational time scale we study implications of hyperbolic discounting for climate change policy when the probability of a climate induced catastrophe depends on the stock of greenhouse gasses we characterize the set of markov perfect equilibria mpe of the inter generational game amongst a succession of policymakers each policymaker reflects her generation s preferences including its hyperbolic discounting for a binary action game we compare the mpe set to a restricted commitment benchmark we compare the associated constant equivalent discount rates and the willingness to pay to control climate change with assumptions and recommendations in the stern review on climate change ymy picture of the world is drawn in perspectivey i apply my perspective not merely to space but also to time ramsey

endogenous discounting and climate policy under risk of abrupt climate change the occurrence hazard is added to the social discount rate as a result the social discount rate 1 increases and 2 turns endogenous to the global warming policy the second effect bears profound policy implications that are magnified by economic growth in particular we find that greenhouse gases ghg emission should be terminated at a finite time so that the ensuing occurrence risk will vanish in the long run due to the public bad nature of the catastrophic risk the second effect is ignored in a competitive allocation and unregulated economic growth will give rise to excessive emissions in the long term the ghg emission paths under the optimal and competitive growth regimes lie at the extreme ends of the range of feasible emissions