Climate variability and the intensifying impacts of climate change present a growing range of socio-economic challenges. Even if mitigation efforts expand in the next decade, significant climate change will continue to impact such areas as water availability and quality, public health, the frequency and intensity of damage from extreme weather events, and the availability of ecosystem services. A growing sense of urgency is spurring the search for effective adaptation strategies that can reduce the vulnerability of communities to current climate, and prepare them for the coming change. The development of adaptation strategies is challenging because there is considerable uncertainty about the exact nature of the risk posed by climate. Scientific information has the potential to assist decision-making by clarifying the risk and the attendant uncertainty, but communication between the scientific and policy-making communities has not always been effective.

The development of effective adaptation strategies based on climate science is hampered by lack of evidence documenting the approaches that have worked, the conditions under which they work, for whom they work, and why. Evidence that clearly attributes outcomes to particular interventions would help to build the knowledge needed to design climate science-based adaptation programs that are effective under different conditions. The well-developed discipline of program evaluation has been applied to rigorously assess the effectiveness of social programs such as educational initiatives, job training programs, and anti-poverty programs for a long time, but the methods of program evaluation have rarely been extended to programs in other sectors. However, interest in adaptation to climate is growing in the evaluation community, along with attention to tailoring evaluation methods that meet the special challenges posed by climate science-based adaptation programs.

The paper will review the main approaches to program evaluation, and will discuss the challenges that climate science-based adaptation strategies pose for existing approaches to program evaluation. We will focus on evaluation problems posed by strategies that apply science to reduce vulnerability to climate risk in urban settings in the United States, building on lessons from developing an evaluation program for the NOAA-funded RISA program, the Consortium for Climate Risk in the Urban Northeast (CCRUN). The challenges and approaches to evaluation that we discuss should be relevant to other RISA programs as well as to adaptation programs more generally.