加征关税如何影响美国贸易逆差及全球福利——基于美元本位下两国动态一般均衡框架的分析

本文构建了一个包含美元本位特征的两国模型,在此基础上分析了美国加征关税及引发的贸易摩擦对美国贸易逆差和全球福利的影响,并详细探讨了相关传导机制。在基准模型设定下,美国单方面加征20%关税会使得美国贸易逆差占GDP比重小幅缩小约0.40个百分点,美国长期稳态GDP下降约2.50%,其他国家GDP下降约1.10%,美国居民福利上升约0.60%,其他国家居民福利下降约1.20%。美国单方面加征关税在抑制全球贸易和生产的同时,会通过更加不公平的国际贸易恶化全球福利分配。当其他国家采取报复性措施时,其他国家自身福利并不会进一步恶化,但美国福利会大幅下滑,同时美国贸易逆差相对规模变化不大。贸易摩擦博弈的“囚徒困境”特征在一定程度上能够解释贸易战的发生。削弱美元本位地位能促进国际贸易公平性的提升,进而能减弱贸易摩擦带来的负面影响、提升全球福利水平,并能有效缩窄美国贸易逆差。

How Increasing Tariffs Affects the U.S. Trade Deficit and Global Welfare: An Analysis Based on a Two-Country Dynamic General Equilibrium Framework Incorporating the Dollar Standard

During recent years protectionism has come to dominate U.S. trade policy. The U.S. has tried to narrow its long-standing large trade deficit and to protect its industries by imposing tariffs on other countries, refusing to support multilateral trading systems, and by other means. Relevant data show that since the collapse of the Bretton Woods system and the establishment of the Jamaican system in the 1970s, the global economic imbalances that are exemplified by the U.S. trade deficit have continued for more than 40 years. Although these imbalances have shown some volatility, in essence they are a set of long-term phenomena. In addition, the U.S. has maintained a long-term trade deficit with almost all of its main trading partners, not just China, and thus the U.S. trade deficit is also a structural phenomenon. In fact, the dollar-standard characteristic of the current international monetary system is one of the root causes of the long-term U.S. trade deficit. The questions explored in this paper are as follows. If the important role of the dollar standard in determining the persistent U.S. trade deficit is taken into account, can the U.S. tariffs draw down the size of the U.S. trade deficit, and how do these tariffs affect the welfare of global residents？ What would happen if other economies retaliated against the U.S.？ In the face of a U.S.-sponsored trade war, could weakening the dollar standard boost the welfare of other economies？ To answer these questions, this paper constructs a two-country dynamic general equilibrium model that incorporates the characteristics of the dollar standard. Based on this model, the paper analyzes the impacts of U.S. tariffs and the trade war on both the U.S. trade deficit and on global welfare, while discussing the relevant transmission mechanism in detail. Under the benchmark model setting, if the U.S. unilaterally imposes an extra 20% tariff, it will reduce the U.S. trade deficit-GDP ratio by about 0.40 percentage points. In addition, the U.S. long-term steady-state GDP will fall by about 2.50%, while the overall GDP of other countries will fall by about 1.10%. U.S. welfare will rise by about 0.60%, and the welfare of other countries will fall by about 1.20%. The unilateral increase in tariffs imposed by the U.S. will curb global trade and production, and worsen the distribution of global welfare through unfair terms of international trade. When other countries take retaliatory measures, that is, when the trade war breaks out, the welfare of other countries will not deteriorate further, but U.S. welfare will fall sharply, and the relative scale of the U.S. trade deficit will not change much. The “prisoner's dilemma” feature of the trade war game can, to a certain extent, explain the occurrence of the trade war. Weakening the dollar standard can help to promote fairness in international trade, which can weaken the negative impacts of the trade war, raise the level of global welfare, and effectively narrow the U.S. trade deficit. This paper offers two main contributions to the existing literature. First, it analyzes the long-term effects that the U.S. tariffs and trade war have on the U.S. trade deficit and on global economic imbalances. This analysis involves constructing a quantitative macroeconomic general equilibrium model, which has been lacking in the existing literature. Second, this paper discusses the impacts of the U.S. tariff and trade war with full consideration for the factor of the dollar standard, which is one important factor that has been neglected in the existing literature. Therefore, this paper's analysis is better aligned with the reality of the world economy than previous studies.