Faculty of Economics, University of Cambridge, Cambridge CB3 9DD, UK.
Science. 2013 Apr 19;340(6130):324-8. doi: 10.1126/science.1224664.
Growing concerns that contemporary patterns of economic development are unsustainable have given rise to an extensive empirical literature on population growth, consumption increases, and our growing use of nature's products and services. However, far less has been done to reach a theoretical understanding of the socio-ecological processes at work at the population-consumption-environment nexus. In this Research Article, we highlight the ubiquity of externalities (which are the unaccounted for consequences for others, including future people) of decisions made by each of us on reproduction, consumption, and the use of our natural environment. Externalities, of which the "tragedy of the commons" remains the most widely discussed illustration, are a cause of inefficiency in the allocation of resources across space, time, and contingencies; in many situations, externalities accentuate inequity as well. Here, we identify and classify externalities in consumption and reproductive decisions and use of the natural environment so as to construct a unified theoretical framework for the study of data drawn from the nexus. We show that externalities at the nexus are not self-correcting in the marketplace. We also show that fundamental nonlinearities, built into several categories of externalities, amplify the socio-ecological processes operating at the nexus. Eliminating the externalities would, therefore, require urgent collective action at both local and global levels.
人们越来越担心当代经济发展模式是不可持续的，这引发了大量关于人口增长、消费增加以及我们对自然产品和服务的日益增长的使用的实证研究。然而，对于理解人口-消费-环境关系中起作用的社会-生态过程，我们所做的理论研究还远远不够。在这篇研究文章中，我们强调了我们每个人在生育、消费和使用自然环境方面所做决策的外部性（即对他人包括未来的人的未被计算的后果）的普遍性。外部性是资源在空间、时间和意外情况下分配效率低下的一个原因；在许多情况下，外部性也加剧了不平等。在这里，我们确定和分类了消费、生殖决策和自然环境使用中的外部性，以便为来自关系交点的数据构建一个统一的理论框架。我们表明，在市场中，交点处的外部性不会自我纠正。我们还表明，几种外部性类别中内置的基本非线性会放大交点处的社会-生态过程。因此，消除外部性需要在地方和全球各级采取紧急的集体行动。
