Uncertainty and Climate Change

Uncertainty is pervasive in analysis of climatechange. How should economists allow for this? And how have they allowed for it? This paperreviews both of these questions.     

Restoration of a Depleted Transboundary Fishery Subject to Climate Change: A Dynamic Investment Under Uncertainty with Information Updates

Environmental and Resource Economics - We model the evolution of a trans-boundary marine fishery, which is based on the harvesting of a single “highly-migratory” stock and is beginning...     

Updating Beliefs Under Risk and Uncertainty

It is possible to represent decision makers’ beliefs on the algebra , rather than alone. Doing so allows us to represent decision makers’ perceptions of risk on one part of the algebra, and their perceptions of uncertainty on the other. This paper shows that such beliefs can be updated in a ‘Bayesian’ manner and that the resulting representation of beliefs is reasonable relative to some other approaches. The model of belief formation and decision making is then used to explain some instances of anomalous economic behaviour.     

新兴技术风险评估中的风险性和不确定性

在技术的风险评估中,人们首先往往要确定环境条件是有风险的,还是不确定有风险的.尤其是在新兴高技术不断涌现的环境下,人们通常没有足够的信息对决策环境做出明确的分类.本文以碳纳米管的风险评估作为案例指出,对高技术的风险评估,关键的要素是技术发展判断和结果预见.因此,在对新兴技术风险进行定量评估的同时,应持有适当的风险怀疑态度,最好能够考虑到不确定性条件下风险评估的决策策略,由此可以划分为风险性条件下的决策和不确定性条件下的决策.两点值得考虑的建议是:第一,加强决策的现实化和逼真度,在某种意义上,可以将决策选择作为现实世界的实验来看待;第二,加强对决策环境定量信息的审议,建立多方叁与的风险评定和决策选择机制.     

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.     

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.     

Optimal Policy under Uncertainty and Learning about Climate Change: A Stochastic Dominance Approach

Global climate change presents a classic problem of decision making under uncertainty with learning. We provide stochastic dominance theorems that provide new insights into when abatement and investment into low carbon technology should increase in risk. We show that R&D into low-carbon technologies and near-term abatement are in some sense opposites in terms of risk. Abatement provides insurance against the possibility of major catastrophes; R&D provides insurance against the possibility that climate change is marginally worse than average. We extend our results to the comparative statics of learning.     

Flood Risk Information,Actual Floods and Property Values: A Quasi‐Experimental Analysis

Hedonic property price analysis tells us that property prices can be affected by natural hazards such as floods. This paper examines the impact of flood‐related variables (among other factors) on property values, and examines the effect of the release of flood risk map information on property values by comparing the impact with the effect of an actual flood incidence. An examination of the temporal variation of flood impacts on property values is also made. The study is the first of its kind where the impact of the release of flood risk map information to the public is compared with an actual flood incident. In this study, we adopt a spatial quasi‐experimental analysis using the release of flood risk maps by Brisbane City Council in Queensland, Australia, in 2009 and the actual floods of 2011. The results suggest that property buyers are more responsive to the actual incidence of floods than to the disclosure of information to the public on the risk of floods.     

Biofuels and Climate Change Mitigation: A CGE Analysis Incorporating Land-Use Change

We examine the impact of a “green network effect” in a market characterized by consumers’ environmental awareness and competition between firms in terms of both environmental quality and product prices. The unique aspect of this model comes from the assumption that an increase in the number of consumers of green (brown) product increases the satisfaction of each green (brown) consumer. We show that, paradoxically, when the network effect of a green product is higher than that of a brown product, this externality reduces product environmental quality and raises consumption of the green product. Conversely, when the network effect of the brown product is higher, the externality improves product environmental quality and raises consumption of the brown product. In both cases, the network effect does not affect the overall pollution level. The externality correction requires the use of three optimal fiscal policies: an ad valorem tax on products, an emission tax, and a subsidy or a tax on the green purchase. A second-best optimum can also be reached through the green taxation.     

Valuation and Management of Fishing Resources Under Price Uncertainty

The traditional expected-net-present-value methods cannot properly capture the management flexibility and strategic value aspects of a fishery, and may understate its value. Instead, this paper develops a Real Options model to conceptualize and evaluate fishery exploitation flexibility. Specifically, general models to value the opportunity to either exploit or invest in a fishery are presented. They suffice to determine not only these values, but also the optimal policy for opening, closing, delaying and setting its harvest rate. The sustainable case in which the harvest rate equals the natural net growth function is also considered. Concerning the exploitation decision, it is found that, as could be expected, the higher the resource price the higher the value of this opportunity in both models (general and sustainable). However, the resource stock affects both models differently. As to the investment opportunity, its value is always lower than the exploitation opportunity because of investment costs. Finally, numerical simulations are run in order to illustrate the nature of the solution. Sensitivity analysis concerning the influence of the tax rate, convenience yield, risk-free interest rate and price volatility on the value of the fishery is also reported. Earlier versions of this paper have benefited from conference participants at the Young Economists Conference 2000 (Oxford University), Tenth Biennial Conference of the International Institute of Fisheries Economics and Trade (Oregon State University), XXV Simposio de Análisis Económico (Universidad Autónoma de Barcelona, Spain) and Seminar at the Dpt. Fundamentos del Análisis Económico (Universidad del País Vasco, Spain). We especially thank Prof. Ian Bateman and two anonymous referees whose insightful comments have enabled us to eliminate several errors and to improve the presentation. Murillas gratefully acknowledges doctoral fellowship from Ministerio de Educación y Ciencia (AP96), and financial support from the Xunta de Galicia (PGIDT01PXI30004PR) and from the Ministerio de Ciencia y Teconología (SEC 2001-3700). The usual disclaimer applies.     

On the Uncertainty About the Total Economic Impact of Climate Change

This paper uses a vote-counting procedure to estimate the probability density function of the total economic impact as a parabolic function of global warming. There is a wide range of uncertainty about the impact of climate change up to 3°C, and the information becomes progressively more diffuse beyond that. Warming greater than 3°C most likely has net negative impacts, and warming greater than 7°C may lead to a total welfare loss. The expected value of the social cost of carbon is about $29/tC in 2015 and rises at roughly 2% per year.     

中国保险企业信息技术外包策略选择及风险分析

信息技术外包是保险公司信息技术资源管理的重要战略,而IT外包成功的关键在于正确选择外包策略。本文就我国保险企业IT外包的动因、面临的问题和现状进行了阐述,进而在外包理论的指导下给出了我国保险企业IT外包策略的选择。同时,结合风险评估方法、修正期望效用理论与项目风险管理技术,建立了一套IT外包项目风险管理模型。     

An Experimental Study of Risk Aversion in Decision-making Under Uncertainty

This paper presents the findings of an experimental study of risk aversion in decision making under uncertainty. When presented with a series of gambles, subjects determined the certainty-equivalent wealth of each gamble. Risk aversion was measured by the Markowitz risk premium of the decision. The fixed effects regression model indicates the significant influence of the first three moments of a probability distribution in determining the risk premium. These results lend support to the rules of mean-variance and third-degree stochastic dominance. The extent of influence is also affected by the individual’s age, but not by gender, wealth or schooling.     

气候变化的经济分析

气候变化在经济学上提出了独一无二的挑战,这是迄今为止范围最大、规模最大的市场失灵现象。文章探讨了经济发展与气候变化之间的互动关系：从市场失灵的角度切入,通过阐述气候变化对经济发展的影响,探讨政府和企业对气候变化所产生的影响做出的反应,从而提出中国应对这种“市场失灵”现象应采取的措施。     

Impact of Climate Change and International Prices Uncertainty on the Sudanese Sorghum Market: A Stochastic Approach

This paper simulates the possible sorghum price change and the related probability of occurrence under different rainfall scenarios and in a context of price uncertainty in international markets. The empirical investigation is based on the stochastic approach. Results indicate an expected increase in sorghum price due to a high level of uncertainty in precipitation and in international market price, the most change likely produced by the latter, and the need to alter the agricultural view of policy making to include a market perspective.     

Climate Policy Under Fat-Tailed Risk: An Application of Dice

Uncertainty plays a significant role in evaluating climate policy, and fat-tailed uncertainty may dominate policy advice. Should we make our utmost effort to prevent the arbitrarily large impacts of climate change under deep uncertainty? In order to answer to this question, we propose a new way of investigating the impact of (fat-tailed) uncertainty on optimal climate policy: the curvature of the optimal carbon tax against the uncertainty. We find that the optimal carbon tax increases as the uncertainty about climate sensitivity increases, but it does not accelerate as implied by Weitzman’s Dismal Theorem. We find the same result in a wide variety of sensitivity analyses. These results emphasize the importance of balancing the costs of climate change against its benefits, also under deep uncertainty.     

新兴技术管理的“评-研-商”模型及其风险评估

本文将新兴技术管理分为技术评估、技术研发和技术产品商业化三个阶段,建立了"评-研-商"阶段模型,并从企业内部研发和外部市场两方面对各阶段可能存在的风险因素进行了分析。针对传统的现金流折现法在评估新兴技术研发推广项目风险方面的不足,本文引用了实物期权方法中的盖斯克模型对新兴技术项目管理进行风险评估。     

气候变化伦理研究评述

气候变化日益成为国际社会的一个热门话题。关于对气候变化问题的国际辩论经历了一个从科学、经济学和政治学争论到伦理争论的历程。气候变化是一个典型的＂全球伦理问题＂,气候变化伦理问题的关键是利益冲突。要解决＂缓解＂和＂适应＂气候变化、碳排量分配的合理性、发展中国家的发展空间及其补偿等一系列问题,必须要对气候公正原则、共同而有区别的责任等问题获得共识。