自由贸易及跨界污染背景下的国际环境政策协调

摘要

This paper builds a welfare function considering transboundary pollution damages,and derives one country’ s optimal pollution tax and compares it with the optimal tax when the world welfare maximizes in the context of free trade in order to show the need for the coordination of environmental policies among different countries.This paper considers four cases,and the analysis results show only when this country is small and pollution does not cross borders,is there no need for international coordination.But when this country is large or pollution crosses borders,this country acting individually will not usually achieve desirable world welfare,thus there is the need for international coordination to maximize world welfare.The pollution policies of large countries have the trade term effects,therefore exporting countries have an incentive to set too high pollution tax,whereas importing countries to set too low pollution tax,both seeking to turn the terms of trade in their own favor.When pollution crosses borders,individual country usually has an incentive to free-ride,thus sets relaxed environmental policies.%文章构建了一个考虑跨界污染损害的福利函数,推导出自由贸易背景下某国的最优污染税,并与世界福利最大化时的最优污染税进行比较,以说明国家间环境政策协调的必要性。文章考虑了四种情况,分析结果表明,只有在该国为小国且污染不跨界时不需要国际协调;当该国为大国或者污染跨界时,单个国家的独立行为通常不会产生合意的世界福利水平,此时需要国际协调以实现世界福利最大化。大国的污染政策具有贸易条件效应,因而出口国有设定过高污染税的激励,而进口国则会设定过低的污染税,双方都寻求转变贸易条件以有利于本方。而污染跨界时单个国家通常会有＂搭便车＂的激励,此时会实施较为宽松的环境政策。