This report examines adaptation and mitigation within an integrated framework. Global and regional costs of adaptation are assessed dynamically and the resulting benefits are quantified. This is accomplished by developing a framework to incorporate adaptation as a policy variable within three Integrated Assessment Models (IAMs); the global Dynamic Integrated model of Climate and the Economy (DICE), the Regional Integrated model of Climate and the Economy (RICE), and the World Induced Technical Change Hybrid (WITCH) model. The framework developed here takes into account investments in reactive adaptation and in adaptation "stocks", as well as investments in building adaptive capacity. This report presents the first inter-model comparison of results on adaptation costs using the emerging category of adaptation-IAMs. Results show that least-cost policy response to climate change will need to involve subsantial amounts of mitigation efforts, investments in adaptation stock, reactive adaptation measures and adaptive capacity to limit the remaining damages.

SummaryIt has become commonly accepted that a successful climate strategy should compound mitigation and adaptation. The accurate combination between adaptation and mitigation that can best address climate change is still an open question. This paper proposes a framework that integrates mitigation, adaptation, and climate change residual damages into an optimisation model. This set-up is used to provide some insights on the welfare maximising resource allocation between mitigation and adaptation, on their optimal timing, and on their marginal contribution to reducing vulnerability to climate change. The optimal mix between three different adaptation modes (reactive adaptation, anticipatory adaptation, and investment in innovation for adaptation purposes) within the adaptation bundle is also identified. Results suggest that the joint implementation of mitigation and adaptation is welfare improving. Mitigation should start immediately, whereas adaptation somehow later. It is also shown that in a world where the probability of climate-related catastrophic events is small and where decision makers have a high discount rate, adaptation is unambiguously the preferred option. Adaptation needs, both in developed and developing countries, will be massive, especially during the second half of the century. Most of the adaptation burden will be on developing countries. International cooperation is thus required to equally distribute the cost of adaptation. Keywords AbstractIt has become commonly accepted that a successful climate strategy should compound mitigation and adaptation. The accurate combination between adaptation and mitigation that can best address climate change is still an open question. This paper proposes a framework that integrates mitigation, adaptation, and climate change residual damages into an optimisation model. This set-up is used to provide some insights on the welfare maximising resource allocation between mitigation and adaptation, on their optimal timing, and on their marginal contribution to reducing vulnerability to climate change. The optimal mix between three different adaptation modes (reactive adaptation, anticipatory adaptation, and investment in innovation for adaptation purposes) within the adaptation bundle is also identified. Results suggest that the joint implementation of mitigation and adaptation is welfare improving. Mitigation should start immediately, whereas adaptation somehow later. It is also shown that in a world where the probability of climate-related catastrophic events is small and where decision makers have a high discount rate, adaptation is unambiguously the preferred option. Adaptation needs, both in developed and developing countries, will be massive, especially during the second half of the century. Most of the adaptation burden will be on developing countries. International cooperation is thus required to equally distribute the cost of adaptation.

SummaryThis work develops a framework for the analysis at the macro-level of the relationship between adaptation and mitigation policies. The FEEM-RICE growth model with stock pollution, endogenous R&D investment and emission abatement is enriched with a planned-adaptation module where a defensive capital stock is built through adaptation investment. Within this framework the optimal path of planned adaptation, the optimal inter and intra temporal mix between adaptation, mitigation and investment in R&D, and the sensitivity of a strategy to each other is identified. The major conclusions of this research show that adaptation, mitigation and R&D are strategic complements as all concur together to the solution of the climate change problem; nonetheless the possibility to adapt reduces the need to mitigate and partly crowds out other forms of investment like those in R&D. The optimal intertemporal distribution of strategies is also described: it requires to anticipate mitigation effort that should start already when climate damages are low and postpone adaptation intervention until they are substantial. Thus the possibility to adapt is not a justification to delay abatement activities. A sensitivity analysis demonstrates the robustness of these results to different parameterizations, in particular to changes in expected climate-change damages and in the discount rates. Keywords AbstractThis work develops a framework for the analysis at the macro-level of the relationship between adaptation and mitigation policies. The FEEM-RICE growth model with stock pollution, endogenous R&D investment and emission abatement is enriched with a planned-adaptation module where a defensive capital stock is built through adaptation investment. Within this framework the optimal path of planned adaptation, the optimal inter and intra temporal mix between adaptation, mitigation and investment in R&D, and the sensitivity of a strategy to each other is identified. The major conclusions of this research show that adaptation, mitigation and R&D are strategic complements as all concur together to the solution of the climate change problem; nonetheless the possibility to adapt reduces the need to mitigate and partly crowds out other forms of investment like those in R&D. The optimal intertemporal distribution of strategies is also described: it requires to anticipate mitigation effort that should start already when climate damages are low and postpone adaptation intervention until they are substantial. Thus the possibility to adapt is not a justification to delay abatement activities. A sensitivity analysis demonstrates the robustness of these results to different parameterizations, in particular to changes in expected climate-change damages and in the discount rates.