Article written by 2008 DPDF Human Dimensions of Global Environmental Change Fellow Seth D. Baum and William E. Easterling, featured in Mitigation and Adaptation Strategies for Global Change, Volume 15, No. 6: 

Discounting is traditionally interpreted as the technique for comparing the values of costs and benefits which occur at different points in time. It endeavors to incorporate how humans trade off values to be received in the future versus value received immediately into economic analysis. Interpreted as such, discounting neglects important spatial influences on how values are compared, thereby hindering cost-benefit analyses of climate change adaptation. In this article, we present new theory on space-time discounting and use it to analyze aspects of how humans adapt to climate change. Three climate change adaptation cases are considered. First, analysis of crop indemnity payments to farmers shows that failure to discount across space and time yields inaccurate evaluations of adaptation projects. Second, adaptation efforts of the Commonwealth of Nations show irregular patterns of international cooperation that suggest spatial discounting of adaptation which are not found in temporal discounting. Third, the nexus between climate change, migration, and conflict shows how various forms of space-time discounting can influence whether climate change and migration will lead to conflict. Collectively, these cases demonstrate the analytical power of the space-time discounting theory and also show how the complexity of climate change adaptation can challenge and strengthen this theory. Finally, this article’s analysis demonstrates that proper discounting must include space as well as time.