The bioeconomics of tritrophic systems: applications to invasive species

Adapted species in nature are assumed to have solved renewable resource management problems, and this is examined here using a physiologically based model of energy acquisition and allocation. Newly established invasive species are merely in an early phase of this process in their new environment. Analogies between the economies of humans and other species are used to develop an objective function for individual utility of energy allocation. The objective function includes the physiologically based population dynamics models of the consumer and resource species in a food chain as constraints. The model applies to all trophic levels in a food chain including human harvesting of renewable resources (see also Regev et al. (Regev, U., Gutierrez, A.P., Schreiber, S., Zilberman, D., 1998. Biological and Economic Foundation of Renewable Resource Exploitation. Ecological Economics. 26 (3), 227-242.)).Specifically, the analysis:

• (1)Attempts to combine ecological and economic theory;
• (2)Points out the importance of time frame in the two economies (evolutionary vs. market time);
• (3)Examines the effects of expected uncertainty due to environmental hazards in defining energy acquisition and allocation strategies in two invasive aphid species at the extremes of so called r- and K-strategies and the well adapted Central American cotton–cotton bollweevil system;
• (4)Evaluates the effects of changes in behavioral and physiological parameters and environmental degradation on the abundance of resource and consumer species.

     

Hope springs eternal: learning and the stability of cooperation in short horizon repeated games

This paper considers learning rates in finitely repeated prisoners’ dilemmas. If players think their opponents might be relatively cooperative (e.g., tit-for-tat or grim types), they will cooperate in finitely repeated prisoners’ dilemmas (see Kreps et al., J. Econom. Theory 27 (1982) 245). However, if there are actually no cooperative types, players will eventually learn this and cooperation will break down. This paper shows that this learning is extremely slow, so it will take an extremely long time for cooperation to break down.Thus, suppose the world is either “good” or “bad.” The probability of a grim type is δ>0 if the world is good, and zero if the world is bad. Successive generations pair up to play finitely repeated prisoners’ dilemmas. Players observe play in previous generations and use Bayes’ rule to update their prior, π, that the world is good. We show that, if the world is really bad, then π falls per generation on average. Thus, if δ is small, there is less cooperation if the world is good, but cooperation may become more stable. For a representative 19 period repeated prisoners’ dilemma, beliefs fall one percentage point on average after a thousand generations.To derive these learning rates, we must refine existing results on the sensitivity of repeated games to Kreps et al. (1982) type perturbations. Specifically, we show cooperation is possible in perturbed prisoners’ dilemmas repeated O(log(1/δ)) times. This improves significantly on the O(1/δ) results in previous work. The paper thus provides two new reasons why cooperation tends to be stable, even in short horizon repeated games.     

On the spatial representation of preference profiles

Given a set of alternatives with multiple attributes, I characterize the set of preference profiles that are representable by weighted versions of a class of utility functions indexed by a parameter δ > 0, where δ ≥ 1 corresponds to the set of Minkowski’s (1886) metric functions. In light of the starkly different consequences between representability with δ ≤ 1 or with δ > 1, I propose a test to empirically estimate δ and I discuss the theoretical and empirical implications for spatial models of political competition.     

Market dynamics, dynamic resource management and environmental policy in the context of (strong) sustainability

In this paper, we investigate the relationship between market dynamics, dynamic resource management and environmental policy. In contrast to static market entry games, this paper draws attention to the effects of market dynamics on resource dynamics et vice versa, because (1) we show that feedback processes are necessary for obtaining a better understanding of what drives the dynamics between the evolution of common-pool resources and the number of harvesters and more importantly, (2) this analysis provides an environment discussing sustainability in an appropriate inasmuch dynamic way. The paper makes the following points: based on a co-evolutionary model, which incorporates resource and market dynamics simultaneously, it is shown that an increasing number of harvesters does not necessarily imply a lower stock of the common-pool resource in the long run. Further it is shown that a tax-scheme establish an output-sharing solution for coping with the overuse of common-pool resources. This results is in contrast to the prevailing literature, which mainly discusses tax-schemes and out-sharing as substitutes rather than as complements for solving the commons-problem. This conclusion holds even if we additionally assume harvesting-cost-reducing technological progress. On the other side if policy interventions ceased, strong resource sustainability in the sense of resource conservation is not possible, given technological progress is a relevant issue.     

Transboundary Marine Resources and Trading Neighbours

The importance of space in analyzing issues pertaining to renewable resources can hardly be overstated. Many such resources are mobile and spatially heterogeneous with respect to bio-economic variables, with important implications for both domestic management regimes and for international externalities and policy interactions. This paper uses a simple general-equilibrium framework to show that acknowledging the inter-jurisdictional mobility of a resource such as fish has the potential to alter or qualify some of the conservation and welfare results obtained in the canonical models. The previous literature on trade and renewable resources has focused on cases where national resource stocks are independent. Brander and Taylor (Can J Econ 30(3):526?C552, 1997a; Resour Energy Econ 19(4):267?C297, 1997b; J Int Econ, 1998a; Am Econ Rev, 1998b) find that trade leads to resource stock depletion for an open-access resource-exporting country, while the non-resource exporter is necessarily diversified. In contrast, we find that the country with a comparative advantage in the resource good may gain from a conservation standpoint, while its partner can specialize in the manufactured good and may incur conservation and even welfare losses from trade.     

On two competing mechanisms for priority-based allocation problems

We consider the priority-based allocation problem: there is a set of indivisible objects with multiple supplies (e.g., schools with seats) and a set of agents (e.g., students) with priorities over objects (e.g., proximity of residence area). We study two well-known and competing mechanisms. The agent-optimal stable mechanism (AOSM) allots objects via the deferred acceptance algorithm. The top trading cycles mechanism (TTCM) allots objects via Gale's top trading cycles algorithm. We show that the two mechanisms are equivalent, or TTCM is fair (i.e., respects agents’ priorities), or resource monotonic, or population monotonic, if and only if the priority structure is acyclic. Furthermore, if AOSM fails to be efficient (consistent) for a problem, TTCM also fails to be fair (consistent) for it. However, the converse is not necessarily true.     

The economics of the illicit drugs-for-guns trade and growth

Ever since US president Richard Nixon declared a war on drugs in 1971, different drug control policies have been implemented in both consumer and producer countries. These include policies ranging from crop eradication to an interdiction of drug shipments to outright legalization of drug possession. In this paper we develop a novel endogenous growth framework that unifies international trade, drugs control and accounts for consumers’ rational addiction and optimizing choice of drug consumption. Our results emphatically show that a one size-fits-all approach to drug control is ineffective. We show that there exists a production - consumption growth trade-off around the policy priority not previously documented in the literature. Moreover, we show that in the absence of a fundamental change to drug demand, drug control policies are unlikely to reduce illicit trades for drugs and guns in the long run.     

How not to measure sustainable value (and how one might)

Sustainability is a complex multidimensional concept that entails economic, environmental, and social aspects. The sustainable value (SV) method developed by F. Figge and T. Hahn [Ecol. Econ. 48(2004) 173-187] is one of the most promising attempts to measure sustainability performance of firms. SV measures corporate contributions to sustainability by valuing resource use based on the opportunity cost, which must be estimated. This paper critically examines Figge and Hahn's estimator for opportunity cost, and shows that the proposed estimator rests on a number of strong, unrealistic assumptions. Evidence from Monte Carlo simulations conducted by authors shows that the proposed estimator performs very poorly even under ideal conditions. Having identified shortcomings in the SV method, we review some econometric approaches with a proven statistical foundation, which might be usefully applied in the present context.     

Spatial Welfare Economics Versus Ecological Footprint: A Sensitivity Analysis Introducing Strong Sustainability

The aim of this paper is a sensitivity analysis with the core-periphery model of ‘new economic geography’ put forward in Grazi et al. (Environ Resour Econ 38:135–153, 2007). This model comprises interregional trade, agglomeration advantages and resource (land) use or environmental externalities. Grazi et al. (2007, GBR) compare a social welfare (SW) indicator with the ecological footprint (EF) indicator for measuring spatial sustainability of a set of land use configurations. Their main result is that the SW and the EF indicator can yield completely different rankings and only for extreme parameterizations of environmental externalities the rankings coincide. We adapt the model by interpreting total natural land as a resource constraint and differentiate between weak and strong sustainability. In a sensitivity analysis we show that the main results of GBR (2007) correspond to the case of weak sustainability in our adapted model version. In the case of strong sustainability our adapted model version shows the same welfare rankings for both indicators without the extreme parameterization that is necessary to obtain the same results in the original GBR (2007) model.     

The fundamentals of sovereign debt sustainability: evidence from 15 OECD countries

We study the sustainability of sovereign debt accumulation in 15 OECD countries using quarterly data from 1980 to 2010 with a focus on how and in what countries debt sustainability changed after the commencement of the Euro Convergence Criteria in 1997 as well as after the financial meltdown in 2007. We define sustainability as the validity of the inter-temporal budget constraint of the government and test a sufficient condition motivated by Bohn (Q J Econ, 113(3):949–963, 1998) using single-country and pooled regressions. We find evidence that the Euro Convergence Criteria contributed to the sustainability of debt accumulation. Further, while the yield spreads suggest the debt crisis is a problem of the southern Euro countries, we find a lack of debt sustainability for Greece, Portugal and France but not for Italy and Spain. In terms of debt sustainability, the crisis adversely affected primarily stand-alone countries rather than members of the European Monetary Union. Nevertheless, yield spreads increased more in the southern countries of the monetary union than in stand-alone countries. Our results support the view that countries within a monetary union are more prone to investors’ sentiments than stand-alone countries.     

Foresight: A major tool in tackling sustainable development

For many decades, the concept of sustainability has been highly successful in public policies and even in the business world.¹ Nowadays, all initiatives must be sustainable and are primarily assessed on that criterion. However, the efforts made to construct specific methods dedicated to building sustainable strategies seem rather weak. Futurists themselves underestimate the relationship between sustainable development and foresight, even if they are talking about sustainable planning.² They remain generally unaware that foresight could be a major tool in tackling sustainability as well as one of the best methods of preparing sustainable strategies and policies.Indeed, one of the biggest problems in sustainability approaches is the simplistic way used to define the concept, for instance, by using only the very first part of the 1987 the Bruntland report Our Common Future and by limiting the fields of activity on sustainability to the three pillars of the OECD model: economy, social questions, environment.At the Copenhagen United Nations Climate Change Conference (December 2009), it seemed forgotten that sustainability is already an old issue in which futurists were heavily involved at the time of the United Nations Stockholm Environment Conference (1972), in the Limits to Growth Report, published by the Club of Rome (1972)³ and in the OECD Interfutures Foresight, spurred on by Jacques Lesourne (1978).⁴Since that time (forty years ago!) researchers and consultants have learned how to deal with the concept of sustainability, how to analyze it as an ultimate aim for society as a whole as well as a complex object that needs to be approached with adequate methods such as systemic analysis.As Christian Stoffaës said, the aim of foresight is sustainable development in a changing world. As a result, the ultimate aim of strategic foresight appears to be clear: it is sustainability. This article highlights that fundamental relationship as we see it today.⁵     

Conditions for Sustainable Optimal Economic Development

This paper shows that, for dynamic optimizing economies with different types of natural resource, environmental, and human‐made capital stocks, a necessary and sufficient condition for permanently sustaining an optimal utility/consumption level is the stationarity of the current‐value Hamiltonian. For economies whose development is not exogenously and directly affected by time (i.e., time‐autonomous economies), this stationarity condition generalizes Dixit et al.’s (1980 ) “zero‐net‐aggregate‐investment” rule of sustain‐ability, which in turn generalizes Solow‐Hartwick’s sustainability rule. For non‐autonomous economies, the stationarity condition is not generally fulfilled, and the current‐value Hamiltonian under (over) estimates the true welfare level by an amount equal to the discounted value of the net “pure time effect.” For the non‐autonomous case of a time‐dependent utility discount rate, a general condition on the discount rate function (of which the hyperbolic discount rate function is a special case) upholds the results obtained for autonomous cases. The paper concludes with a discussion of policies that promote both optimality and sustainability objectives.     

Technical coefficients for bio-economic farm household models: a meta-modelling approach with applications for Southern Mali

In recent years, different types of bio-economic models have been developed to support the analysis of the potential impact of agrarian policies on changes in land use, sustainable resource management and farmers' welfare. Most bio-economic models rely on series of discrete input–output coefficients for current and improved cropping and livestock activities, whereas mathematical programming procedures are usually applied to analyse optimum allocative choice. Adequate procedures for the smooth integration of biophysical information into economic decision models are, however, not readily available. This article provides a new and comprehensive framework for the incorporation of technical input–output coefficients derived from agroecological simulation approaches into bio-economic farm household models. Therefore, continuous production functions are estimated for the production side of the farm household model, making use of meta-modelling principles. It is shown that meta-modelling offers considerable scope for improving the specification and behaviour of bio-economic farm household models. This procedure is applied in a farm household model developed for the analysis of farmers’ response to agrarian policies in Southern Mali. Results are presented for the behaviour of a typical household, focusing attention on the trade-offs between farm income and soil nutrient balances under free market conditions and with constraints on labour, capital and animal traction markets. The stability and robustness of the model is analysed through a simulation of the impact of higher input costs for land use and fertiliser applications.     

On the Enforcement of Cooperative Environmental Policies

This paper investigates the sustainability of Pareto optimal policies for the replenishment of renewable resources shared by two countries with asymmetrical wealth. It does so within a two-country neoclassical growth model with externality. In the absence of commitment, it identifies simple self-enforcing mechanisms that implement social optima for a typical international resource (clean air) and a parametrization of the model to the United States and a country five times poorer. Such mechanisms are trigger strategies involving transfers of wealth between countries and threats of economic isolation in case of defection. Necessary transfers can represent up to 2.6% of U.S. wealth. Journal of Economic Literature Classification Numbers: Q20, C73, C68     

Repeated games with present-biased preferences

We study infinitely repeated games with perfect monitoring, where players have β-δ preferences. We compute the continuation payoff set using recursive techniques and then characterize equilibrium payoffs. We then explore the cost of the present-time bias, producing comparative statics. Unless the minimax outcome is a Nash equilibrium of the stage game, the equilibrium payoff set is not monotonic in β or δ. Finally, we show how the equilibrium payoff set is contained in that of a repeated game with smaller discount factor.     

Dynamics of the North-South welfare gap and global sustainability

The vast heterogeneity among nations in terms of economic and demographic characteristics is evident, despite being overlooked in some global studies. In this heterogeneity, it is possible to identify some distinct aggregate classes differing at some very fundamental level: developing (South) nations and developed (North) nations may have very different, asymmetric problems, goals and structures. This study investigates these two distinct groups of socio-economic systems, as they interact in a context of global sustainability. We identify population, economic growth, welfare gap, energy supply and pollution as key issues and analyze them using a systems perspective. A dynamic feedback model, which discriminates the two groups of nations, is constructed to study the dynamics of variables related to the above key issues. The model is tested using extensive data between the years 1980-2005. According to the reference behavior covering the period 1980-2050, it is not viable to close the welfare gap between North and South, given the current prevailing non-renewable-resource-based growth system. A non-renewable-resource-based system adopted by the economic system of growing South would take the global system even closer to its limits. It is observed that indicators like reserve-to-demand ratio fail to provide reliable signals for a timely transition to alternative resources, and a very serious economic recession due to resource scarcity is likely to develop in the next couple of decades. By coupling the demographic and economic dynamics, it is shown that an economic slowdown due to a resource scarcity may have a dramatic widening effect on the already existing welfare gap. Scenario and policy experiments verify the widely accepted importance of stabilizing the population growth in South, transition to alternative energy resources, and investment support to the South in this transition simultaneously in order to reduce the welfare gap between the two blocks. It is observed that enthusiastic targets for an energy transition may have a serious negative impact on the welfare level experienced in South, whereas an energy transition in South supported by North seems to have the most desirable outcome regarding the welfare gap.     

Mixed Equilibrium in a Downsian Model with a Favored Candidate

This paper examines competition in the standard one-dimensional Downsian model of two-candidate elections, but where one candidate (A) enjoys an advantage over the other candidate (D). Voters' preferences are Euclidean, but any voter will vote for candidate A over candidate D unless D is closer to her ideal point by some fixed distance δ. The location of the median voter's ideal point is uncertain, and its distribution is commonly known by both candidates. The candidates simultaneously choose locations to maximize the probability of victory. Pure strategy equilibria often fail to exist in this model, except under special conditions about δ and the distribution of the median ideal point. We solve for the essentially unique symmetric mixed equilibrium with no-gaps, show that candidate A adopts more moderate policies than candidate D, and obtain some comparative statics results about the probability of victory and the expected distance between the two candidates' policies. We find that both players' equilibrium strategies converge to the expected median voter as A's advantage shrinks to 0. Journal of Economic Literature Classification Numbers: C72, D72.     

Is an Exhaustible Resource Economy Sustainable?

The paper focuses on two alternative concepts of sustainability dominating the literature: (i) maximum permanently maintainable consumption level (Fisherian income) and (ii) the amount of consumption that leaves total value of wealth intact (Hicksian income). In the context of a pure exhaustible resource economy, the author derives an explicit relationship between the two sustainability criteria and shows that while such an economy is not sustainable in the former sense, it is in the latter sense provided social preferences are represented by a logarithmic utility function. The implications of the two concepts for greening of national income are derived. Finally, the paper shows the range of values of the parameters of the model for which the utilitarian optimal path can be close to paths satisfying the alternative sustainability criteria, suggesting that such outcomes are less likely for very poor resource‐dependent countries than for the rich ones.     

People,skills, and resources: an interaction model for world population growth

A model is set up that yields the equation followed by world population (P), past and present: P = A/(D - t)^M, where t is time and A, D, and M are constants. Cumulated historical population estimates confirm this hyperbolical pattern first noticed by Cailleux, Meyer, and Foerster. Technological indices should grow according to the same pattern; partial confirmation of this part of the model is presented. The growth acceleration crisis that we are now facing may have had a counterpart around 4500 B.C., during the neolithic agricultural revolution. World-population projections up to 2000 A.D. are discussed in the light of the interaction model, with and without resource limitations.