Limited (Energy) Supply, Monetary Policy, and Sunspots
Authors: Nils Gornemann, Sebastian Hildebrand, and Keith Kuester
Abstract
In a simple New Keynesian open economy setting, the paper analyzes how local input shortages influence policy transmission and equilibrium determinacy. Shortages increase the elasticity of the local price of the scarce factor, affecting the cyclicality of marginal costs and incomes. This alters the slopes of both the Phillips and IS curves, crucially influencing monetary and fiscal policy transmission. These changes depend on factor ownership and consumption propensities. Theoretically, shortages can also raise the risk of self-fulfilling fluctuations if rising prices boost incomes for agents with high consumption propensities.
Introduction
The international macroeconomic environment is increasingly affected by shortages of inputs, driven by various factors such as natural disasters and geopolitical policies. These shortages can significantly change the sensitivity of prices to local demand conditions, even for a small open economy. This paper examines the implications of such supply constraints for monetary transmission and macroeconomic stability in a New Keynesian open economy model. Domestic production uses labor and another input factor, with the latter's income accruing to domestic households and a foreign economy demanding domestic products.
Model Setup
The core of the model is similar to Blanchard and Galí (2009), with additions including liquidity-constrained households, supply constraints for the input factor, and fiscal policy shielding households and firms from fluctuations in the input’s price. Supply constraints alter the cyclicality of the factor's price, changing the slopes of the Phillips curve and the distribution of income across households and countries. This, in turn, affects the effectiveness and distributional consequences of monetary and fiscal policy.
Analytical Framework
To derive the effects of an input shortage, a simplified version of the model is used, assuming the constrained factor is only used in production and trade is balanced. This allows for a representation with three key equations: a Phillips curve, a dynamic IS equation, and a Taylor rule. Two supply regimes are compared: one where the factor is in abundant supply at a fixed price, and another where the factor’s supply to the domestic economy is fixed, with its price moving flexibly to clear the market.
Key Findings
- Phillips Curve: Supply constraints tend to steepen the Phillips curve, except when price movements are accompanied by strong wealth effects on domestic labor supply.
- IS Curve: The impact on the IS curve depends on how the constraints affect the cyclical distribution of incomes, which varies based on the composition of after-tax incomes of different agents (Ricardian households, hand-to-mouth households, and the foreign economy).
- Monetary Policy Effectiveness: Energy supply constraints make monetary easing more inflationary and less effective at stimulating domestic demand, leading to a lower "sacrifice ratio" in terms of real activity and consumption.
- Fiscal Policy Impact: Energy supply constraints mean that fiscal transfers to hand-to-mouth households crowd in domestic consumption less and are more inflationary.
Quantitative Exploration
The model is calibrated to the German economy, associating the input factor with energy and building a scenario reflecting energy shortages before and after the 2022 Russian invasion of Ukraine. The analysis shows that energy supply constraints make monetary easing more inflationary and less effective, while fiscal transfers are less effective in crowding in domestic consumption.
Conclusion
The distribution of income is crucial in determining the implications of supply constraints. Supply constraints can raise the risk of self-fulfilling fluctuations and require a response by monetary policy to inflation stronger than prescribed by the Taylor principle.
