Variability among climate change scenarios produces great uncertainty in what is the best allocation of resources among investments to protect environmental goods in the future. Previous research shows Modern Portfolio Theory (MPT) can help optimize environmental investment targeting to reduce outcome uncertainty with minimal loss of expected level of environmental benefits, but no work has yet identified the types of cases for which MPT is most useful. This article assembles data on 26 different conservation cases in three distinct ecological settings and develops new metrics to evaluate how well MPT can reduce uncertainty in future outcomes of a set of environmental investments. We find MPT is broadly but not universally useful and works best when multiple investments have negatively correlated outcomes across climate scenarios; a second‐best investment has expected value almost as good as the value in the best investment; or multiple investments have little uncertainty in ecological outcomes.

中文翻译：

---

投资组合理论何时可以帮助环境投资计划降低气候风险，以降低未来的环境结果，而它何时不能

气候变化情景之间的可变性对于未来在保护环境商品的投资中最佳的资源分配方式产生了极大的不确定性。先前的研究表明，现代证券组合理论（MPT）可以帮助优化环境投资目标，以最大程度地减少预期的环境效益损失，从而减少结果的不确定性，但是目前尚无任何工作能够确定MPT最有用的案例类型。本文在三个不同的生态环境中收集了有关26个不同保护案例的数据，并开发了新的指标来评估MPT可以如何降低一系列环境投资的未来结果的不确定性。我们发现，MPT广泛但并非普遍有用，并且当多种投资在整个气候情景中的结果具有负相关关系时，MPT效果最佳。次优投资的预期价值几乎与最优投资的价值相同；或多项投资在生态结果方面几乎没有不确定性。