
As of 2010, urban areas are home to more than half of the world's population, produce at least 70% of carbon-dioxide emissions from fossil fuels, and emit a significant amount of anthropogenic methane, but represent a small fraction of the Earth’s land surface. Currently, greenhouse gas emissions estimates for many cities are either unavailable or are generated using self-reported data from particular sectors, and contain significant uncertainties. Although methods for comprehensive measurement of urban emissions have been tested in smaller cities with stable emissions, these techniques...