Is Trade in Permits Good for the Environment?
研究了当国家间交易差异化商品时，排放许可证交易对环境政策的影响，发现可交易许可证总是导致更高污染，且许可证价格低于国内边际损害。
We analyze the impact of trade in emission permits on environmental policy when countries trade a differentiated good. Pollution is always higher with tradable permits as compared to the case where permits are not internationally tradable. If pollution is a pure global public bad, i.e., the marginal damage from transboundary pollution is the same as that from local pollution, the permit price under trade equals the domestic marginal damage from own emissions. If pollution is not a pure global public bad, i.e., the marginal damage from transboundary pollution is less than that from local pollution, trade results in a permit price lower than the domestic marginal damage from own emissions—pollution is higher under trade relative to autarky. Regardless of the nature of transboundary pollution, the permit price (equivalent pollution tax) is lower and pollution is higher with internationally tradable permits than with nontradable permits.