Recent controversy has led to calls for increased standardization and transparency in the methods used to synthesize climate change research. Though these debates have focused largely on the biophysical dimensions of climate change, human dimensions research is equally in need of improved methodological approaches for research synthesis. Systematic review approaches, and more recently realist review methods, have been used within the health sciences for decades to guide research synthesis. Despite this, penetration of these approaches into the social and environmental sciences has been limited. Here, we present an analysis of approaches for systematic review and research synthesis and examine their applicability in an adaptation context. Customized review frameworks informed by systematic approaches to research synthesis provide a conceptually appropriate and practical opportunity for increasing methodological transparency and rigor in synthesizing and tracking adaptation research. This review highlights innovative applications of systematic approaches, with a focus on the unique challenges of integrating multiple data sources and formats in reviewing climate change adaptation policy and practice. We present guidelines, key considerations, and recommendations for systematic review in the social sciences in general and adaptation research in particular. We conclude by calling for increased conceptual and methodological development of systematic review approaches to address the methodological challenges of synthesizing and tracking adaptation to climate change.

We develop and apply a systematic mixed-methods literature review methodology to identify and characterize how climate change adaptation is taking place in developed nations. We find limited evidence of adaptation action. Where interventions are being implemented and reported on, they are typically in sectors that are sensitive to climate impacts, are most common at the municipal level, facilitated by higher-level government interventions, with responses typically institutional in nature. There is negligible description of adaptation taking place with respect to vulnerable groups, with reporting unequal by region and sector. The methodology offers important insights for meta-analyses in climate change scholarship and can be used for monitoring progress in adaptation over time.