Green Golden Rule Research Articles

Monetary Policy, Neutrality, and the Environment

AbstractWe study the interaction between monetary/fiscal policies in a Ramsey–Sidrauski model augmented with the “Green Golden Rule.” We demonstrate conditions whereby monetary and fiscal policy under different utility and preference assumptions are or are not environmentally neutral. Despite its nonseparability in utility, we demonstrate that money is environmentally neutral. Policy impacts the environment via the marginal rate of transformation rather than the marginal rate of substitution between consumption and environment. Fiscal policies under a balanced budget are environmentally nonneutral. Only under a nonbalanced budget, when deficits are monetized, is money environmentally nonneutral. Under cash‐in‐advance and transactions costs, money is environmentally nonneutral.

A Green Fiscal Pact for the EU: increasing climate investments while consolidating budgets

ABSTRACT To ensure sufficiently rapid decarbonization to meet the Paris Agreement goals, investments in green infrastructure will have to increase by an estimated 2% of world GDP annually, according to the International Energy Agency. A significant part of that investment will need to be funded with public resources – raising major tensions between consolidation needs after the high deficits during the pandemic and the need to increase investments. We consider this trade-off in the European Union, which has set itself one of the most ambitious climate targets in the world. The additional public investment required to meet the European Union’s climate goals is around 0.6% of GDP annually during this decade, which might increase if the green transition is accelerated due to Russia’s invasion of Ukraine. Budget consolidation can be done at a moderate pace in line with EU fiscal rules if those rules are interpreted flexibly, but past consolidation episodes resulted in major public investment cuts. A ‘green golden rule’ –excluding net green investment from the fiscal indicators used to measure fiscal rule compliance– is proposed as the most promising option to address this tension and would provide a positive incentive to undertake such investments. However, the uncertain growth impact of green public spending and the risks to growth from climate change create difficult trade-offs in fiscally weaker countries. Better regulatory policy and a higher price on emissions should in parallel incentivise private green investment and reduce public costs. These ingredients should be combined to form a ‘Green Fiscal Pact’. Key policy insights Public investments tend to be cut in fiscal consolidation episodes by vote-maximising politicians and thus need to be treated differently in fiscal rules. Increasing green public investments will be difficult in the upcoming consolidation period. A ‘green golden rule’ –excluding net green public investment from the fiscal rule indicators– is proposed as the best option to incentivise public climate investment. Policymakers need to underpin such a rule by clearly defining what constitutes emission-reducing climate investments and monitoring compliance. Fossil fuel subsidies should also be eliminated, and private climate investment should be incentivised through appropriate taxation and regulation. Climate change may tighten budget constraints in countries with already high debt levels because of its negative growth effects, so these countries should delay the introduction of the green golden rule.

Hyperbolic discounting and the time‐consistent solution of three canonical environmental problems

AbstractIn this paper I propose a time‐consistent method of discounting hyperbolically and apply it to three canonical environmental problems: (i) optimal renewable resource use, (ii) the tragedy of the commons, and (iii) economic growth and pollution. I show that, irrespective of potentially high initial discount rates, time‐consistent hyperbolic discounting leads always to a steady state of maximum yield, or, if the environment enters the utility function, a steady state where the Green Golden Rule applies. While (asymptotic) extinction is a real threat under exponential discounting it is impossible under time‐consistent hyperbolic discounting. This result is also confirmed for open‐access resources. In a model of economic growth and pollution, hyperbolic discounting establishes the Golden Rule of capital accumulation and the modified Green Golden Rule.

Hyperbolic Discounting and the Time-Consistent Solution of Three Canonical Environmental Problems

In this paper I propose a time-consistent method of discounting hyperbolically that contains the discount rate implied by Gamma discounting as a special case. I apply the discounting method to three canonical environmental problems: (i) optimal renewable resource use, (ii) the tragedy of the commons, (iii) economic growth and pollution. I then compare results with those for conventional exponential discounting using the normalization that both methods provide the same present value of an infinite constant flow. I show that, irrespective of potentially high initial discount rates, time-consistent hyperbolic discounting leads always to a steady state of maximum yield, or, if the environment enters the utility function, a steady state where the Green Golden Rule applies. While (asymptotic) extinction is a real threat under exponential discounting it is impossible under time-consistent hyperbolic discounting. This result is also confirmed for open access resources. In a model of economic growth and pollution, hyperbolic discounting establishes the Golden Rule of capital accumulation and the Modified Green Golden Rule.

Monetary Policy, Neutrality and the Environment

We study the interaction between monetary and fiscal policies in a Ramsey-Sidrauski model augmented with environmental capital. Equilibrium solutions are studied through the “Green Golden Rule”. Despite the non-separability of money in utility and intertemporally non-separable preferences, money is environmentally neutral. Policy impacts the environment via the marginal rate of transformation rather than the marginal rate of substitution between consumption and environment. Fiscal policies, lump sum and distortionary, under a balanced budget, are also environmentally non-neutral. Only under a non-balanced budget, when deficits are monetized, is money environmentally non-neutral. In alternative approaches (Cash-in-Advance, Transactions Costs), money is environmentally non-neutral. JEL Classification: E52, E62, H23

On an environmental sustainability problem

SummaryBeltratti et al proposed an environmental sustainability problem and stressed the importance of two related control problems, namely, the discounted utilitarian problem and the long‐run utility problem. From the analysis of the latter, they obtained the definition of the Green Golden Rule (GGR). We discuss the optimal steady‐state solutions of the first problem and provide new results, completing the known information on it. Then we tackle the second problem and its equivalent NLP problem of maximizing the steady‐state utility. We obtain that the solutions to the NLP problem depend on the capital accumulation features, like those of the first problem. This corrects and completes the original analysis of the GGR.

The Green Golden Rule: Habit and Anticipation of Future Consumption

We derive the Green Golden Rule (GGR) in the Habit Formation (HF) and Anticipation of Future Consumption (AFC) frameworks. Since consumption is the key variable of GGR, time non-separabilities in preferences over consumption streams, given by the AFC and HF, may have important impacts on the environment and sustainability. We demonstrate that agents who smooth their consumption patterns, according to the HF hypothesis, are more likely to preserve the environment than those who anticipate future consumption or who do not so smooth consumption. JEL Classification: D90, Q56

The green golden rule: Habit and anticipation of future consumption

We derive the Green Golden Rule (GGR) in the Habit Formation (HF) and Anticipation of Future Consumption (AFC) frameworks. Since consumption is the key variable of GGR, time non-separabilities in preferences over consumption streams, given by the AFC and HF, may have important impacts on the environment and sustainability. We demonstrate that agents who smooth their consumption patterns, according to the HF hypothesis, are more likely to preserve the environment than those who anticipate future consumption or who do not so smooth consumption.

CLIMATE POLICY WITHOUT INTERTEMPORAL DICTATORSHIP: CHICHILNISKY CRITERION VERSUS CLASSICAL UTILITARIANISM IN DICE

Unlike discounting and the damage function, the social welfare function has not received so much attention in the debate on climate economics. An important challenge has been to combine efficiency and equity considerations in a single social welfare framework. The Chichilnisky criterion is one way to resolve this. We consider its implementation in the climate-economy model Dynamic Integrated Climate-Economy (DICE), and compare results for different damage functions, namely the standard one in DICE and the one proposed by Weitzman implying potential large climate damages at high temperature increases. We calculate optimal climate policy for different parameter settings and compare the results with those under the green golden rule (only final utility matters) and classical utilitarianism (no discounting). Optimal emission abatement trajectories turn out to be very different between standard discounted utilitarianism, classical utilitarianism and Chichilnisky specifications. The results are very sensitive to the damage function, the climate sensitivity parameter and especially the “Chichilnisky weight” given to utility of generations in the far future. We discuss conditions and reasons for preferring either classical utilitarianism or the Chichilnisky criterion, and conclude that a critical factor is the time horizon used in climate policy analysis. Adopting sustainable preferences as formalized by the Chichilnisky criterion in climate policy analysis has the advantage that the very long-term implications of greenhouse gases in the atmosphere on the environment and human welfare are not downplayed.

Sustainability and intertemporal equity: a multicriteria approach

In (macro)economics literature, the need to consider sustainability and intertemporal equity issues leads to propose different criteria (discounted utilitarianism, green golden rule, Chichilnisky criterion) in order to define social welfare. We compare and assess the outcomes associated to such alternative criteria in a simple macroeconomic model with natural resources and environmental concern (Chichilnisky et al. in Econ Lett 49:174–179, 1995), by relying on a multicriteria approach. We show that among these three criteria, the green golden rule (discounted utilitarianism) yields the highest (lowest) welfare level, while the Chichilnisky criterion leads to an intermediate welfare level which turns out to be increasing in the weight attached to the asymptotic utility. These results suggest that completely neglecting finite-time utilities and focusing only on the asymptotic utility is not only more sensible from a sustainability point of view but also from a social welfare maximization standpoint.

Menominee implementation of the Chichilnisky criterion for sustainable forest management

For over a century, the Menominee Tribe harvested timber from their forest; during this time the volume of standing timber increased, a sign of sustainable forest management. The Menominee selection of a green golden rule path has been made through consistent and long-standing efforts to reject the analysis provided by industrial forestry. The choices made by the Menominee Tribe in managing its forest are also an empirical application of the Chichilnisky criterion, which seeks to balance the interests of the present generation with those of future generations. The Menominee state that they are “borrowing the forest from their grandchildren,” and hence reject the “tyranny of the present.” They also reject the “tyranny of the future,” because they harvest from the forest in the present and do not spend all resources saving for the future. They emphasize the long term and multiple forest outputs; they limit harvest while using the forest for current generations with a lumber mill. When their system was displaced by the US Government management and by Congressional efforts to terminate the tribe's reservation status, the Menominee utilized judicial alternatives and social movements in order to return to their concept of sustainable forest management.

What really matters: Discounting, technological change and sustainable climate

This paper discusses the interplay between the choice of the discount rate, greenhouse gas mitigation and endogenous technological change. Neglecting the issue of uncertainty it is shown that the Green Golden Rule stock of atmospheric carbon is uniquely determined, but is not affected by technological change. More generally it is shown analytically within the framework of a reduced model of integrated assessment that the optimal stationary stocks of atmospheric carbon depend on the choice of the discount rate, but are independent of the stock of technological knowledge. These results are then reinforced numerically in a fully specified integrated assessment analysis.

Sustainable exploitation of a natural resource: a satisfying use of Chichilnisky’s criterion

Chichilnisky’s criterion for sustainability has the merit to be, so far, the unique explicit, complete and continuous social welfare criterion that combines successfully the requirement of efficiency with an instrumental notion of intergenerational equity (no dictatorship of the present and no dictatorship of the future). But it has one drawback: when applied in the context of renewable resources, and with a constant discount factor, there exists no exploitation path that maximizes this criterion. The present article suggests a way to cope with this problem. The idea is to restrict attention to the set of convex combinations between the optimal discounted utilitarian program and the stationary program leading to the green golden rule. It is shown that an optimal path in this set exists under rather weak sufficient conditions on the fundamentals of the problem. Some ethical properties of this approach are also discussed. In some cases, it turns out that the restricted solution implies no loss of efficiency and benefits intermediate and infinitely distant generations.

A Blueprint for Optimal Intertemporal Consumption Under Environmental Constraints: The Modified Green Golden Rule

The notion of sustainability represents the core of the theoretical and political debate on the potential conflict between economic growth and environmental quality. A clear definition of what sustainability means, although still controversial, is indeed a possible keystone to better understanding what is Environmental Economics needed for. To this end, this paper aims at providing a theoretical analysis by means of a neo-classical framework, and consequently define a modified version of the common green golden rule that an economy might follow to drive the system onto the path where both optimal intertemporal consumption and sustainable growth are finally reconciled.

Sustainable growth, renewable resources and pollution

Our intention is to present a growth model with an environmental resource which has its own regeneration process. The stock of this resource serves as a source of utility and an input to production. We also intend to introduce a negative externality caused by a pollution flow which we assume to be proportional to production. In the context of this model, it is shown that, by using the utility level of the Green Golden Rule as a generalization of the Ramsey's bliss point for solving an optimal growth problems with a zero discount rate, an optimal path converges to the Green Golden Rule configuration.

The Green Golden Rule

We introduce a growth model with environmental assets as a source of utility and an input to consumption and production. In this model we develop the Green Golden Rule, a generalization of the golden rule of neoclassical growth theory. We apply this to the case where the object is the maximization of long-run or limiting utility rather than long-run consumption.

Sustainable Growth and the Green Golden Rule

We study a growth model with an environmental asset which is a source of utility and an input to consumption and production. The stock of this asset follows its own ecological dynamics, which are affected by economic activity. We study the implications of an approach to ranking sequences of consumption and environment over time that place weight both on the characteristics of the sequence over any finite period and on its very long run or limiting characteristics. Chichilnisky [5] has called these preferences. The criterion shows more intertemporal symmetry than the discounted utilitarian approach. which clearly emphasizes the immediate future at the expense of the long run. In this respect Chichilniskys criterion captures some of the concerns of those who argue for sustainability and for a heightened sense of responsibility to the future. To characterize optimal paths we define the green golden rule, the path which maximizes long-run sustainable utility from consumption and environment.

The environment and the long run: a comparison of different criteria

Summary We use growth models with natural resources to study the consequences of a ranking of intertemporal paths, due to Chichilnisky, which places weight on their very long run or limiting characteristics as well as on their characteristics over any finite period. This criterion shows more intertemporal symmetry or egalitarianism than the discounted utilitarian approach, which clearly emphasizes the immediate future at the expense of the long run. In this respect it captures the concenrs of those who argue for sustainability and for a heightened sense of responsibility to the future. In some of the examples that we consider, the long-run characteristics of paths optimal by this criterion are a mixture of those of utilitarian paths and the “green golden rule” (the configuration which maximizes long-run sustainable utility from consumption and environment).