市场结构、环境税与福利效应分析

运用短期局部均衡分析方法研究完全竞争市场和垄断市场条件下环境税对社会福利的影响.结果显示:在完全竞争市场条件下,对企业征收环境税可以增进社会福利.而在垄断市场条件下,环境税的福利效应具有不确定性,这取决于垄断造成的扭曲程度.如果垄断造成的扭曲较小,环境税仍然可以提高社会福利.但无论是增进抑或降低社会福利,对垄断企业征收环境税都不可能实现最优化,因为环境税在矫正污染外部性的同时,垄断造成产量水平下降导致福利损失增加,所以只能追求一个次优的结果,次优环境税低于完全竞争条件下的标准环境税.

An Analysis on the Market Structure,Environmental Taxes and Welfare Effects

This paper analysis the effects of environmental tax on the social welfare under the conditions of perfectly competitive market and monopolistic market,using Short-term partial equilibrium analysis method.We find,in the perfectly competitive market,imposing environmental tax on enterprises can improve social welfare.But social welfare has uncertainty in the monopolistic market and it is up to the distortion of monopoly.We can sure that environmental tax can improve the social welfare if the distortion of monopoly slight.From the analysis,we can draw a conclusion that we can’t make an optimal choice between environmental tax and social welfare in the monopolistic market.As we all know,imposing environmental tax on enterprises can decrease contamination but also decrease enterprise’s output,and so decrease social welfare.We finally have only a sub-optimal choice that in the monopolistic market,we choose a sub-optimal environmental tax lower than that in the perfectly competitive market.