This paper offers insights into the dynamics of carbon emissions in metropolitan regions. These emerge from a system dynamics model of urban land-atmospheric interactions. The paper provides contextual background, outlines modeling methodology, inventories insights and documents policy implications. Section One considers climate change, worldwide urbanization, urban CO2 emissions and urban land-use/transportation dynamics. Section Two identifies the study area, the modeling tool, its dynamic organizing principle, its structure and the scenarios used to explore system behavior. Section Three considers urban CO2 emissions and the mitigating effects of land-use and transportation policies. It compares these to practicable improvements in fossil fuel combustion efficiencies and finds that modifying urban form compare favorably to improving combustion efficiencies. Section Four asserts that, given today’s global-scale inter-metropolitan economic competition, today’s urban challenge will be largely met by cooperation at the metro-regional scale to tame the dynamics of carbon-based metropoli.