城市生态系统服务功能的价值结构分析

本文从城市生态系统价值体系出发,探讨城市自然资本,经济资本和社会资本综合测算的理论与方法,结果表明：示范区的自然总资本以年均４％的速度递减,其真实总资本年均增长率为４．５％而不是国内生产总值的１２．６％,自然资本的增减应成为衡量一个城市或区域是否实现可持续发展的核心指标。城市生态系统中自然资本由持续递减变为递增,是实现人类共同追求的可持续发展目标必由之路。     

Hartwick's rule and maximin paths when the exhaustible resource has an amenity value

This paper studies the maximin paths of the canonical Dasgupta–Heal–Solow model when the stock of natural capital is a direct argument of well-being, besides consumption. Hartwick's rule then appears as an efficient tool to characterize solutions in a variety of settings. We start with the case without technical progress. We obtain an explicit solution of the maximin problem in the case where production and utility are Cobb–Douglas. When the utility function is CES with a low elasticity of substitution between consumption and natural capital, we show that it is optimal to preserve forever a critical level of natural capital, determined endogeneously. We then study how technical progress affects the optimal maximin paths, in the Cobb–Douglas utility case. On the long run path of the economy capital, production and consumption grow at a common constant rate, while the resource stock decreases at a constant rate and is therefore completely depleted in the very long run. A higher amenity value of the resource stock leads to faster economic growth, but to a lower long run rate of depletion. We then develop a complete analysis of the dynamics of the maximin problem when the sole source of well-being is consumption, and provide a numerical resolution of the model with resource amenity. The economy consumes, produces and invests less in the short run if the resource has an amenity value than if it does not, whereas it is the contrary in the medium and long runs. However, and without surprise, the resource stock remains for ever higher with resource amenity than without.     

Disaggregated intertemporal models with an exhaustible resource and technical advance

We compare results of four organizations of an economy that is dependent upon an irreplenishable resource but may develop a new technology that releases that dependence. We find a decentralized competitive organization can replicate the behavior of a centrally planned economy, given an appropriate distribution of initial wealth. This holds whether the R&D is done by the government or by the natural resource sector, so long as borrowing from other sectors is possible. Further, the economy's behavior is independent of whether the resource sector is monopolistic or competitive if and only if the production function is Cobb-Douglas.     

A free lunch in the commons

We derive conditions under which raising costs through a regulatory constraint or a fully expropriated tax can increase the profits arising from a common-pool resource. The basic model assumes a fixed number of identical agents with linear costs selling in a single period at an exogenous price. A necessary and sufficient condition for a cost increase to be profitable is that aggregate output from the resource be locally convex in aggregate effort. We also show that cost increases can be profitable even if price is endogenous, agents are heterogeneous, entry is costless, or agents are playing a Markov-perfect equilibrium of a dynamic game. We also discuss more general welfare implications of the result along with its relation to existing results for a Cournot oligopoly.     

The Role of Prices in Conserving Critical Natural Capital

Abstract: Until recent decades, economic decision makers have largely ignored the nonmarket benefits provided by nature, resulting in unprecedented threats to ecological life‐support functions. The economic challenge today is to decide how much ecosystem structure can be converted to economic production and how much must be conserved to provide essential ecosystem services. Many economists and a growing number of life scientists hope to address this challenge by estimating the marginal value of environmental benefits and then using this information to make economic decisions. I assessed this approach first by examining the role and effectiveness of the price mechanism in a well‐functioning market economy, second by identifying the issues that prevent markets from pricing many ecological benefits, and third by focusing on problems inherent to valuing services generated by complex and poorly understood ecosystems subject to irreversible change. I then focus on critical natural capital (CNC), which generates benefits that are essential to human welfare and have few if any substitutes. When imminent ecological thresholds threaten CNC, conservation is essential and marginal valuation becomes inappropriate. Once conservation needs have been met, remaining ecosystem structure is potentially available for economic production. Demand for this available supply will determine prices. In other words, conservation needs should be price determining, not price determined. Conservation science must help identify CNC and the quantity and quality of ecosystem structure required to ensure its sustained provision.     

Social Capital in Biodiversity Conservation and Management

Abstract:  The knowledge and values of local communities are now being acknowledged as valuable for biodiversity conservation. Relationships of trust, reciprocity and exchange, common rules, norms and sanctions, and connectedness in groups are what make up social capital, which is a necessary resource for shaping individual action to achieve positive biodiversity outcomes. Agricultural and rural conservation programs address biodiversity at three levels: agrobiodiversity on farms, nearby nature in landscapes, and protected areas. Recent initiatives that have sought to build social capital have shown that rural people can improve their understanding of biodiversity and agroecological relationships at the same time as they develop new social rules, norms, and institutions. This process of social learning helps new ideas to spread and can lead to positive biodiversity outcomes over large areas. New ideas spread more rapidly where there is high social capital. There remain many practical and policy difficulties, however, not least regarding the need to invest in social capital formation and the many unresolved questions of how the state views communities empowered to make their own decisions. Nonetheless, attention to the value of social relations, in the form of trust, reciprocal arrangements, locally developed rules, norms and sanctions, and emergent institutions, has clearly been shown to deliver a biodiversity dividend in many contexts. This suggests a need to blend both the biological and social elements of conservation.     

Cheap talk efficacy under potential and actual Hypothetical Bias: A meta-analysis

Cheap Talk (CT) is a common technique employed in stated preference methods of nonmarket valuation to reduce Hypothetical Bias (HB). However, multiple studies have documented its mixed usefulness. Using meta-analysis of 67 studies identified after reviewing over 400 articles, we first show the efficacy of CT while controlling for publication bias. We then investigate when CT is likely to be effective. Our results indicate that on average CT is significant in reducing estimated economic values by about 20% compared to the baseline treatment without implementing CT. Further analysis demonstrates that using CT in the context of public goods, using a budget/substitute reminder, and using CT in conjunction with other HB mitigation strategies improves its efficacy. In addition, we show that CT works better when the actual HB is larger thus one potential reason for previous studies failing to identify positive reduction in potential HB through CT may be because actual HB is small instead of CT being ineffective.     

Resource Depletion and Sustainability in Small Open Economies

Exogenous price changes affect the amount that a small country exporting natural resource commodities must invest to sustain its consumption level. The necessary amount is given by the difference between Hotelling rent and the discounted sum of future terms-of-trade effects (capital gains). The latter term is found to be large relative to the former in the case of petroleum depletion in Indonesia. This suggests that resource-rich countries will need to invest more than previously expected to sustain their consumption levels, if natural resource prices continue their long-term historical decline.     

Towards a 3D National Ecological Footprint Geography

In the last decades several indicators have been proposed to guide decision makers and help manage natural capital. Among such indicators is the Ecological Footprint, a resource accounting tool with a biophysical and thermodynamic basis. In our recent paper (Niccolucci et al., 2009), a three dimensional Ecological Footprint (^3DEF) model was proposed to better explain the difference between human demand for natural capital stocks and resource flows. Such ^3DEF model has two relevant dimensions: the surface area (or Footprint size - EF_size) and the height (or Footprint depth - EF_depth). EF_size accounts for the human appropriation of the annual income from natural capital while EF_depth accounts for the depletion of stocks of natural capital and/or the accumulation of stocks of wastes. Building on the 2009 Edition of the National Footprint Accounts (NFA), global trends (from 1961 to 2006) for both EF_size and EF_depth were analyzed. EF_size doubled from 1961 to 1986; after 1986 it reached an asymptotic value equal to the Earth's biocapacity (BC) and remained constant. Conversely, EF_depth remained constant at the “natural depth” value until 1986, the year in which global EF first exceeded Earth's BC. A growing trend was observed after that. Trends in each Footprint land type were also analyzed to better appraise the land type under the higher human induced stress. The usefulness of adopting such ^3DEF model in the National Footprint Accounts was also discussed. In comparing any nation's demand for ecological assets with its own biocapacity in a given year, four hypothetical cases were identified which could serve as the basis for a new Footprint geography based on both size and depth concepts. This ^3DEF model could help distinguish between the use of natural capital flows and the depletion of natural capital stocks while maintaining the structure and advantages of the classical Ecological Footprint formulation.     

The role of technological change

We develop an optimal growth model that includes several important new features. First, technological change is endogenously related to the growth of “knowledge.” Investment may be directed either towards physical capital or knowledge (or both). Knowledge becomes an effective substitute for scarce resources by increasing the technical efficiency of resource utilization both for consumption and in capital. Nevertheless, a finite quantity resource must be embodied in capital and a finite flow is required for depreciation. Thus, there is an upper limit to technical efficiency and economic growth is thus ultimately limited by the availability of renewable resources. For a simple aggregate production function it is shown that technical efficiency never approaches unity on an optimal path.     

Contingent valuation of ecotourism development in country parks in the urban shadow

To optimise the use and management of Hong Kong's country parks, ecotourism has recently been promoted by the government and echoed by the leisure sector. Visitors' valuation of ecotourism development hitherto remains scant and could add a new dimension to the knowledge and management base. This study estimated the potential value of ecotourism development using the contingent valuation method (CVM). A total of 613 visitors in three country parks were interviewed. The results showed that the bid amounts and the motives to experience and learn more about nature were significant predictors of willingness-to-pay (WTP). The mean and median WTP were, respectively, HK$101.1 and HK$85.0 annually, varying slightly between parks. The differences were associated with the special ecological and accessibility characteristics of individual parks. The results could justify financial support from the government for ecotourism development and associated nature conservation endeavours and promote the incorporation of natural resource valuation in formulation of public policies in Hong Kong and other developing regions.     

Economic growth,international trade,and the depletion or conservation of renewable natural resources

Conservation of renewable natural resources and promotion of economic growth are both sustainable development goals. Here, we study the interdependency between economic growth, international trade, and the use of renewable natural resources—under alternative institutional settings of either open access or full property rights—in an endogenous growth model. We find that if the resource is depleted over time, consumption growth is reduced. Economic growth and international trade only impact resource use when the resource is harvested under full property rights. Then, widening international trade can lead countries to shift from conservation to depletion. Changes in the institutional setting of resource use in one country may have repercussions on trading partners. Our results indicate potential trade-offs between the sustainable development goals and imply that policies focusing on resource use or trade (e.g., international trade bans or certified trade) are not sufficient to prevent resource depletion.     

Social networks and non-market valuations

This paper considers the role of social networks in the non-market valuation of public goods. In the model individuals derive utility both from their own direct enjoyment of the public good and from the enjoyment of those in their network. We find that network structure almost always matters, both for utility and for valuation. The network increases aggregate valuation when it assigns higher importance, that is, stronger connections, to individuals with higher private values for the public good. The model provides a theoretical foundation for the idea of opinion leaders who have disproportionate influence over their communities. Specifically, opinion leaders are individuals assigned high importance by the network, and projects favored by opinion leaders tend to be favored by the network as a whole. The model can also guide future empirical studies by enabling a more structural approach to non-market valuation in a socially connected group.     

The interpretation of capitalized hedonic prices in a dynamic environment

This paper considers the biases in hedonic price estimates of environmental variables. It is shown that using the current values of such variables can seriously bias the measure of the true effect of that variable when the future is changing. Although the bias can be in either direction most plausible examples considered show that we tend to underestimate such prices. A discussion of the relation between rental and capital value of hedonic prices follows from the distinction between present and future levels of environmental effects.     

Using the paired comparison methodology to assess environmental values in the coastal zone of Ghana

Like many developing countries, Ghana is grappling with environmental issues, such as the degradation of coastal natural resources. In an attempt to ameliorate the current state of affairs, broad institutional arrangements and policy interventions have been put in place. However coastal natural resources are still being overexploited and the effects of this are felt more strongly by certain groups (such as women and the rural poor) than others. This has led to the argument pointing to an urgent need to include local resource users as active participants in environmental decision making and to incorporate their environmental values in the management of coastal natural resources. Using empirical data from women in two Ghanaian coastal communities, this paper highlights the importance of exploring how the environmental attitudes and values of women might be considered in the management of local coastal natural resources. It assesses effectiveness of the paired comparison methodology in this respects and how this method can be also used to prioritise their environmental concerns. The results show that in both areas respondents place the greatest importance on the coastal natural resources as sources of wealth creation and of food, values which are often described as being “anthropocentric”. The paper thus argues that having discovered that the ecological value placed on natural resources is low, initiatives that could win the support of people would be those that link the livelihood and wellbeing to coastal NRM. It emphasizes the fact that conservation cannot exist outside of people and social systems; nor will it succeed unless they are linked to the welfare of resource users.     

Valuation of natural capital under uncertain substitutability

Natural capital is complex to value notably because of the high uncertainties surrounding the substitutability of its future ecosystem services. We examine a Lucas economy in which a consumption good is produced by combining different inputs, one of them being an ecosystem service that is partially substitutable with other inputs. The growth rate of these inputs and the elasticity of substitution evolve in a stochastic way. We characterize the socially efficient ecological discount rates that should be used to value future ecosystem services at different time horizons. We show that the inverse of the elasticity of substitution can be interpreted as the CCAPM beta of natural capital. We also show that any increase in risk of this beta reduces the ecological discount rate. If our collective beliefs about the elasticity of substitution of ecosystem services are Gaussian, the ecological discount rates go to minus infinity for finite maturities. In that case, a marginal increase in natural capital has an infinite value. We provide a realistic calibration of the model that is coherent with observed asset prices by using the model of extreme events of Barro (2006). The bliss maturity for infinite discount factors is less than 100 years in this calibration.     

Uncertainty,benefit-cost analysis,and the treatment of option value

This paper proposes a new conceptual framework for defining welfare measures under uncertainty: the planned expenditure function. This function describes the locus of expenditures on contingent claims that are required to realize a given level of expected utility. To illustrate the convenience of the framework, it is used to consider the definition of the option price, the appropriate treatment of option value, the valuation of risk changes, and the definition of non-use benefits under uncertainty.     

Price perceptions in water demand

Economists advocate for using the price mechanism to manage water scarcity, but complex nonlinear rate structures prevalent in markets for municipal water obscure price signals. We conduct a randomized field experiment that jointly elicits knowledge about the cost of water and examines the impact of improved information on demand by linking a survey to water billing records. Half of our sample of 30,000 single family homeowners are randomly sent an invitation to a survey that asks questions about the water bill and the costs of water-use activities (e.g. the cost of taking a shower), and subsequently provides personalized accurate information. Results show that consumers have poor information about the marginal price of water and overestimate the costs of using water. Respondents are relatively better informed about their total bill and water consumption. In aggregate, respondents increase water use in response to the survey, potentially due to learning that water is cheaper than they previously thought. Increased consumption is concentrated among low users who are more likely to over-estimate the costs of using water.     

Estimation Using Contingent Valuation Data from a "Dichotomous Choice with Follow-Up" Questionnaire

Dichotomous-choice (referendum) contingent-valuation questions are inefficient in that a very large number of observations is required to identify a distribution of resource values with any degree of accuracy. An alternative questioning strategy introduces a follow-up dichotomous-choice question. We generalize upon previous analyses of this type of data by relaxing the assumption that the identical unobserved resource value motivates both responses. While values implied by the first and second responses are highly correlated and may be drawn from the same distribution, they are definitely not identical. Furthermore, assuming that they are can severely distort the estimated valuation distribution.     

Environmental policy and human capital inequality: A matter of life and death

This paper analyzes the economic implications of an environmental policy when we account for the life expectancy of heterogeneous agents. In a framework in which everyone suffers from pollution but health status also depends on individual human capital, we find that the economy may be stuck in a trap in which inequality rises steadily, especially when the initial pollution intensity of production is too high. We emphasize that such inequality is in the long run costly for the economy in terms of health and growth. Therefore, we study whether a tax on pollution associated with an investment in pollution abatement can be used to address this situation. We show that a stricter environmental policy may allow the economy to escape from the inequality trap while enhancing the long-term growth rate when the initial inequality in human capital is not too large.