Multiple adaptation types with mitigation: a framework for policy analysis

Mitigation and adaptation will be simultaneously implemented in a policy portfolio to reduce the risks of climate change, yet significant differences between the two responses have inhibited understanding of how to appropriately view these two key strategies in a coherent policy framework. For example, the climate-related effects of mitigation are homogenous, global, and realized over the long term, while those of adaptation are heterogeneous over temporal, technological, and damage scales, even within a fixed locality and with a single implementing agent and affected sector.

This paper presents a new framework that conceptualizes tradeoffs across the two strategies in a coherent and policy-relevant way. Two of these differences are fundamental to understanding the relevant relationships and tradeoffs that occur when mitigation and adaptation are considered together: 1) strategy investment lifetimes and limits in relation to climate damages, and 2) strategy behavior under uncertainty. When implemented jointly with mitigation, the most accurate representation of adaptation is as a portfolio of three classes of adaptation investment types with different lifetimes and design capacity ranges for different damage sectors, namely, flexible and short-lived flow spending, committed and long-lived new stock investments, and retrofitting of pre-existing adaptation stock investments. These distinct adaptation types can be integrated with mitigation into an explicit decision analysis framework in order to explore portfolios of mitigation and different adaptation responses over time. We conclude that adaptation should be incorporated into planning as characterized by its longevity as it relates to uncertain but expected damages.