不确定条件下环境政策的时机选择

本文建立了一个连续时间模型，用于分析不确定条件下环境政策的时机选择。模型结果显示，环境政策的采用有两种不可逆性，而且它们在相反的方向上起作用：第一，旨在降低生态危害的政策对社会施加了沉淀成本。它产生立即采用这一政策而不是等待有关生态影响及其经济后果的更多信息的机会成本，这种机会成本使等待而不是现在就采纳政策更可取；第二，环境危害可能部分或完全不可逆。这就意味着立即采用一项政策而不是等待具有沉没收益，即负的机会成本。这种负的机会成本偏离了政策采用中传统的成本一收益分析。因此，现在立即采用一项政策可能是更合适的，即使传统的分析宣称它是不经济的。文章表明，不确定性对环境政策的时机选择有着重要的影响。

Timing Choice of Environmental Policy under Uncertainty

This paper uses a continuous-time model to illustrate an optimal timing problem of environmental policy under uncertainty. The model shows that environmental policy involves two kinds of irreversibilities, and they work in opposite directions. First, policies aimed at reducing ecological damage impose sunk costs on the society. Sunk costs create an opportunity cost of adopting a policy now, rather than waiting for more information about ecological impacts and their economic consequences. Second, environmental damage can be partial or totally irreversible. This means that adopting a policy now rather than waiting has a sunken benefit, i. e. , a negative opportunity cost, which biases traditional cost-benefit analysis of policy adopted. Hence, it may be desirable to adopt a policy now, even though the traditional analysis declares it is uneconomical. This paper shows that the uncertainty does, in general, have significant impact on the timing of environmental policy.