Monitoring Urban Emissions Hotspots
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 have not yet been extended to the more complex environments in growing megacities, and ultimately, to a global urban- monitoring system that can establish baseline-emissions estimates for large cities and help assess the efficacy of
As part of this effort, a network of 14 surface-monitoring sites located within and around the Los Angeles basin provides continuous measurements of the atmospheric concentrations of carbon dioxide, methane, and carbon monoxide. Remote-sensing instruments provide emissions measurements from multiple sites.
Sustained measurement of atmospheric concentrations and emissions sources of