Cities are a key driver of environmental and climatic change, and at the same time significantly impacted by that change. Vulnerability varies spatially and over time, and the complex relationships among climate, ecosystem health, and socioeconomic development call for an integrated theoretical framework within which to study the world's cities. Advances in the fields of industrial ecology, urban metabolism and urban ecology shed light on these relationships. However, much of the current research is found in the form of case studies. Though detailed and relevant, the lack of a cohesive theory precludes standardization of and comparison between methodical experiments pertaining to the relationship between urban systems and global climate change. Aiming to identify and connect underlying issues, and to drive research forward, this study is a synthesis of key emergent theories and continuities in the body of research surrounding urban systems and global change. Thinking of cities as complex open systems integrated within a larger environmental and social context brings us closer to understanding how cities impact/are impacted by climate change and variability. The physical realism and interdisciplinary nature of a unified urban systems theory will facilitate more grounded and effective policy to shape and govern our cities.