Optimal emission-extraction policy in a world of scarcity and irreversibility

This paper extends the classical exhaustible-resource/stock-pollution model with irreversibility of pollution decay, meaning that after reaching some threshold there is no decay of the pollution stock. Within this framework, we answer the question how the potential irreversibility of pollution affects the extraction path. We investigate the conditions under which the economy will optimally adopt a reversible policy, and when it is optimal to enter the irreversible region. In the case of irreversibility it may be optimal to leave a positive amount of resource in the ground forever. As far as the optimal extraction/emission policy is concerned, several types of solutions may arise, including solutions where the economy stays at the threshold for a while. Given that different programs may satisfy the first order conditions for optimality, we further investigate when each of these is optimal. We show that it is never optimal for the economy to stay at the threshold for a while before entering the irreversible region. The optimality analysis is then illustrated by means of a calibrated example. To sum up, for any pollution level, we can identify a critical resource stock such that there exist multiple optima i.e. a reversible and an irreversible policy that yield exactly the same present value. For any resource stock below this critical value, the optimal policy is reversible whereas with large enough resources, irreversible policies outperform reversible programs.     

The environmental Kuznets curve in a world of irreversibility

This paper develops an overlapping generations model where consumption is the source of polluting emissions. Pollution stock accumulates with emissions but is partially assimilated by nature at each period. The assimilation capacity of nature is limited and vanishes beyond a critical level of pollution. We first show that multiple equilibria exist. More importantly, some exhibit irreversible pollution levels although an abatement activity is operative. Thus, the simple engagement of maintenance does not necessarily suffice to protect an economy against convergence toward a steady state having the properties of an ecological and economic poverty trap. In contrast with earlier related studies, the emergence of the environmental Kuznets curve is no longer the rule. Instead, we detect a sort of degenerated environmental Kuznets curve that corresponds to the equilibrium trajectory leading to the irreversible solution. I would like to thank Alain Venditti, Mabel Tidball, Alain Jean-Marie and Thierry Bréchet for their helpfull comments and suggestions. I am deeply grateful to an anonymous referee whose comments have greatly improved the paper.     

Optimal fiscal policy in a world liquidity trap

We construct a model of the international transmission of ‘liquidity trap’ shocks, and examine the case for international coordination of fiscal policy to respond to the liquidity trap. Integrated financial markets tend to propagate liquidity traps. In a global environment, fiscal policy may be effective in raising GDP when the economy is stuck in a liquidity trap, but it does so in a ‘beggar thy neighbor’ fashion; when one economy is in a liquidity trap, the cross country spillover effect of fiscal policy is negative. We examine the welfare optimizing policy response to a liquidity trap when countries coordinate on fiscal policy. Fiscal policy may be an effective tool in responding to a liquidity trap, although it is never optimal to use fiscal expansion sufficiently to fully eliminate a downturn. Moreover, there is little case for coordinated global fiscal expansion. For the most part, the country worst hit by a liquidity trap shock should use its own policies to respond, without much help from foreign policies.     

Optimal monetary policy in a New Keynesian model with endogenous growth

We study optimal monetary policy in a New Keynesian (NK) model with endogenous growth and knowledge spillovers external to each firm. We find that, in contrast with the standard NK model, the Ramsey dynamics implies deviation from full inflation targeting in response to technology and government spending shocks, while the optimal operational rule is backward looking and responds to inflation and output deviations from their long-run levels.     

Optimal fiscal policy in the Uzawa-Lucas model with externalities

Summary. This paper devises a fiscal policy by means of which the first-best optimum equilibrium is attained as a market equilibrium in the Uzawa-Lucas model when average human capital has an external effect on productivity. The optimal policy requires the use of a subsidy to investment in human capital which can be financed by a tax on labor income. Lump-sum taxation is not required to balance the government budget either in the steady state or in the transitional phase. Physical capital income should not be taxed. Alternatively, the optimal growth path can be attained by means of a subsidy to human capital. Received: March 21, 2002; revised version: September 4, 2002 RID="*" ID="*" Financial support from the Spanish Ministry of Science and Technology through PNICDYIT grant SEC2002-03663 is gratefully acknowledged.     

Optimal simple rules for the conduct of monetary and fiscal policy

Stabilization policy involves joint monetary and fiscal rules. We develop a model enabling us to characterize systematic simple monetary and fiscal policy over the business cycle. We principally focus on the following question. What are the key properties of the joint simple rule governing the conduct of systematic stabilization policy? We find that conducting stabilization policy incorporates not only a set of monetary policy choices governed by the so-called ‘Taylor principle’ but also fiscal policy that gives considerable force to automatic stabilizers. Recent US and UK monetary and fiscal choices seem broadly consistent with this model. This result is found to be robust to a number of alternate modeling strategies.     

Optimal monetary policy in a Phillips-curve world

In this paper, we study optimal monetary policy in a model that integrates the modern theory of unemployment with a liquidity model of monetary transmission. Two policy environments are considered: period-by-period optimization (time consistency) and full commitment (Ramsey allocation). When the economy is subject to productivity shocks, the optimal policy is pro-cyclical. We also characterize the long-term properties of monetary policy and show that with commitment the optimal inflation rate is inversely related to the bargaining power of workers. Both results find empirical support in the data.     

Optimal choice of monetary policy instruments under velocity and fiscal shocks

This paper, in the spirit of Poole [Poole, William, 1970. The Optimal Choice of Monetary Policy Instruments in a Simple Macro Model. Quarterly Journal of Economics, 84, 192–216.], studies how differently monetary and fiscal shocks influence the appropriate choice of the monetary policy regime. Velocity shocks are introduced by embedding a stochastic cash-in-advance constraint within the New Keynesian framework. In addition to optimal policy under discretion, three classic rules, interest rate targeting, monetary targeting, and the Taylor rule are ranked under both fiscal and velocity shocks. The non-stationarity of prices under the Taylor rule makes it inferior to the other rules under which prices are stationary. Monetary targeting, by stabilizing aggregate demand under fiscal shocks, outperforms interest rate targeting, while the latter provides a better insulation against velocity shocks. Monetary targeting (under fiscal shocks) and interest rate targeting (under velocity shocks) even outperform the optimal policy under discretion for sufficiently high intertemporal elasticities of consumption substitution.     

An empirical analysis of air pollution emissions policy for the U.K. residential sector

In this paper an analysis of the U.K. government's air pollution emissions policy for the residential sector is undertaken. The analysis covers emissions arising from water and space heating, electric appliances and cooking appliances. Using an integrated economic-engineering model, the effects of the Energy Savings Trust and the imposition of Value Added Tax on residential fuel will be evaluated in terms of energy consumption and pollution emissions. It is found that the initial proposed policy was not sufficiently stringent to meet the government's environmental objectives, and that subsequent events have undermined the government's programme even further. Unless alternative policies are introduced, emissions from the residential sector will play an important role in jeopardizing the ability of the U.K. government to meet its international obligations.     

Financial frictions and optimal stabilization policy in a monetary union

Financial frictions differ across countries and thus cause international differences in the transmission of shocks. This paper shows how the optimal mix of monetary and fiscal policy depends on these country-specific financial frictions. To this end, we build a two-country DSGE-model of a monetary union. Financial frictions are captured by the cost channel approach. We show that the traditional solution to the assignment problem – the common central bank stabilizes the inflation rate at the union level and the national fiscal authorities stabilize the national economies – does not hold in a world with financial frictions. The cost channel decreases the efficiency of monetary policy and increases the need for fiscal stabilization even at the union level. Moreover, the more heterogeneous the union, the more important is fiscal policy in stabilizing shocks. Finally, we evaluate the scenarios in terms of welfare of the representative household.     

Optimal fiscal and monetary policy with sticky wages and sticky prices

We determine the optimal degree of price inflation volatility when nominal wages are sticky and the government uses state-contingent inflation to finance government spending. We address this question in a well-understood Ramsey model of fiscal and monetary policy, in which the benevolent planner has access to labor income taxes, nominally risk-free debt, and money creation. Our main result is that sticky wages alone make price stability optimal in the face of shocks to the government budget, to a degree quantitatively similar as sticky prices alone. Key for our results is an equilibrium restriction between nominal price inflation and nominal wage inflation that holds trivially in a Ramsey model featuring only sticky prices. Our results thus show that when nominal wages are sticky, setting real wages as close as possible to their efficient path is a more important goal of optimal monetary policy than is financing innovations in the government budget via state-contingent inflation. A second important result is that the nominal interest rate can be used to indirectly tax the rents of monopolistic labor suppliers. Taken together, our results uncover features of Ramsey fiscal and monetary policy in the presence of a type of labor market imperfection that is widely-believed to be important.     

Discretionary policy in a monetary union with sovereign debt

This paper examines the interactions between multiple national fiscal policymakers and a single monetary policy maker in response to shocks to government debt in some or all of the countries of a monetary union. We assume that national governments respond to excess debt in an optimal manner, but that they do not have access to a commitment technology. This implies that national fiscal policy gradually reduces debt: the lack of a commitment technology precludes a random walk in steady-state debt, but the need to maintain national competitiveness avoids excessively rapid debt reduction. If the central bank can commit, it adjusts its policies only slightly in response to higher debt, allowing national fiscal policy to undertake most of the adjustment. However, if it cannot commit, then optimal monetary policy involves using interest rates to rapidly reduce debt, with significant welfare costs. We show that in these circumstances the central bank would do better to ignore national fiscal policies in formulating its policy.     

Optimal monetary policy under Calvo pricing with Bertrand competition

We consider a NK model characterized by a small and fixed number of firms competing in prices à la Bertrand and we study the implications for monetary policy under both exogenous and endogenous market concentration. We find that the implied NKPC has a lower slope compared to a standard NK model with atomistic firms, and the determinacy region enlarges assuming a standard Taylor rule. We characterize the impact of competition on the optimal monetary rules within the linear-quadratic approach of Rotemberg–Woodford. The optimal monetary rule requires a less aggressive reaction to inflationary shocks compared to monopolistic competition, but an increase in competition, due to either an increase in substitutability between the goods or in the number of firms, makes it optimal to adopt a more aggressive reaction in front of inflationary shocks. Finally, more competition increases the gains from commitment.     

Monetary policy, oil shocks, and TFP: Accounting for the decline in US volatility

An equilibrium model is used to assess the quantitative importance of monetary policy for the post-1984 decline in US inflation and output volatility. The principal finding is that monetary policy played a substantial role in reducing inflation volatility, but a small role in reducing real output volatility. The model attributes much of the decline in real output volatility to smaller TFP shocks. We also investigate the pattern of output and inflation volatility under an optimal monetary policy counterfactual. We find that real output volatility would have been somewhat lower, and inflation volatility substantially lower, had monetary policy been set optimally.     

Optimal information acquisition and monetary policy

I study optimal monetary policy with an expectational AS curve and private agents who optimally choose their amount of information pertinent to predicting policy. Shocks with time-varying variance (ARCH) induce interesting information acquisition (IA) dynamics; optimal IA affects optimal policy and vice versa. Under discretion, IA dynamics cause time-varying effectiveness of policy because of the expectational AS curve; policy may be rendered completely ineffective. In policy game equilibrium, a fall in the shock’s variance typically induces less IA and raises welfare. In one exceptional case the opposite occurs, a result which does not require implausible unstable equilibria. An agent becoming informed increases the endogenous component of economic volatility; IA therefore has a negative externality. Under commitment policy’s effectiveness is again time-varying, but policy is never completely ineffective: commitment enables the central bank to credibly limit policy’s volatility; this limits private agents’ incentive to become informed, so limits expectation-induced policy neutrality.     

Optimal fiscal policy in a dynamic multicountry world with public services

The authors construct a dynamic one‐good multicountry growth model with productive government spending and perfect capital mobility to study fiscal interdependence among countries. In the case of a source‐based tax, it is found that there is no strategic interaction and that the equilibrium spending/tax mix coincides with the optimal one. In the case of a residence‐based tax system, however, there is strategic interaction across countries and, under noncooperation, countries tend to spend and tax over and above the optimal Pigouvian level.     

Optimal fiscal policy, uncertainty, and growth

This paper analyzes the macroeconomic effects of fiscal policy in a stochastic endogenous growth model. Due to externalities in human capital accumulation, the market allocation is inefficient, thereby justifying government intervention. The uncertainty stemming from technological disturbances affects the growth rate, which can be explained by precautionary motives of risk averse agents. Fiscal policy means consist of a consumption tax, investment subsidies, and bonds. We obtain counter-acting growth effects of investment subsidies, which are differentiated with respect to deterministic and stochastic capital income components. The policy implications from the deterministic model are substantially extended in the stochastic context. A general rule for a welfare maximizing policy is derived, which is represented by a continuum of alternative tax-transfer-schemes. We discuss three benchmark cases, which crucially differ with respect to their implications regarding the size of the government expenditure share.     

Optimal penalty and accounting policy

This study considers risky investment projects under adverse selection and examines optimal penalties for erroneous auditing reports to maximize social welfare. These penalties give firms an incentive to choose accounting policies that maximize social welfare. We characterize the optimal penalties such that efficient firms choose an aggressive accounting policy and inefficient firms choose a conservative accounting policy.     

Optimal fiscal policy in the neoclassical growth model revisited

This paper studies optimal taxation in a version of the neoclassical growth model in which investment becomes productive within the period, thereby making the supply of capital elastic in the short run. Because taxing capital is distortionary in the short run, the government׳s ability/desire to raise revenues through capital income taxation in the initial period or when the economy is hit with a bad shock is greatly curtailed. Our timing assumption also leads to a tractable Ramsey problem without state-contingent debt, which can give rise to debt-financed budget deficits during recessions.