China’s urban agglomerations contribute 64 percent to China’s energy-related CO 2 emissions and thus play a vital role in determining the future of climate change. There is little information available about city-level energy consumption and CO 2 emissions; thus, we employ spatiotemporal modeling using Defense Meteorological Satellite Program/Operational Line-scan System (DMSP/OLS) nighttime light imagery. Our findings show that such agglomerations have in fact experienced a remarkable decline in CO 2 emission intensity—from 0.43 t/thousand yuan to 0.20 t/thousand yuan between 1995 and 2013, which constitutes an average annual decline of 4.34 percent. Despite still very high CO 2 intensities in western China, a convergence of CO 2 intensities across the country has occurred over the last few decades. Using panel regression modeling, we analyze differences in the decline of CO 2 emission intensities due to regional differences in socioeconomic variables such as economic growth, population, economic structure, population density, and characteristics of urbanization. Factors that have hampered the decline of CO 2 intensities are the ongoing industrialization that demands the increase in the production of heavy industry, in infrastructure investment, and in housing stock.