纽约联储-供应链风险下的投入品采购_来自美国制造企业的证据（英）-2025.2_65页_8mb

Summary of "Input Sourcing Under Supply Chain Risk: Evidence from U.S. Manufacturing Firms"

Introduction

• Focus: Examines the impact of climate and supply chain risks on input sourcing decisions by U.S. manufacturers.
• Key Risk Source: Weather-induced ocean shipping time variability, measured using.transaction-level data and wave height data.
• Findings: Shipping delays negatively affect firms' financial outcomes. Firms mitigate risk by diversifying routes and suppliers.

Methodology

• Data: Transaction-level U.S. import data combined with NOAA wave height data. Measures weather-induced shipping risk using residualization and rolling standard deviations.
• Empirical Design: Analyzes effects of weather delays on firm outcomes and correlates traffic with diversification margins (extensive and intensive).
• Theoretica Framework: Extends general equilibrium importing models to incorporate firm heterogeneity and shipping risk.

Empirical Findings

• Weather Effects: Unexpected shipping delays reduce importer sales (6.5%), profits (3.5%), and employment (1%) by one standard deviation.
• Risk Diversification: Higher shipping risk leads to:
  • More routes and suppliers.
  • Reduced concentration in spend across routes/suppliers.
  • Lower total imports due to risk cost.
• Policy-Relevant Shocks: Climate variability, geopolitical disruptions (e.g., Red Sea attacks), and port congestion reduce U.S. real income by 0.4%-1.33%.

Model Contribution

• Theory: Incorporates shipping time risk into a quantitative importing model to show how diversification and domestic substitution respond to risk.
• Calibration: Matches firm-level risk responses. Simulates scenarios for climate change, geopolitical events, and port congestion.

Policy Implications

• Rising climate and geopolitical risks limit firms' ability to avoid narrow sourcing concentrations, potentially constraining supply chain resilience.
• Fragmentation and reshoring may be partial and constrained by delivery risk.

Conclusion

• The study demonstrates that climate-related supply chain risks force U.S. manufacturers to diversify extensively, but this comes with aggregate costs. Firms adapt through multi-modal shipping, yet risks like climate change persistently hinder efficiency gains.

The above summary captures the core findings and structure of the paper in a neutral and professional manner, using markdown formatting for readability.