A global urban carbon monitoring system

Carbon emissions associated with cities - including megacities, smaller urban areas, and power plants - represent the single largest human contribution to climate change. Robust validation of emission changes due to growth or stabilization policies requires that we establish measurement baselines today and begin monitoring representative megacities immediately. An observing system designed to monitor urban carbon emissions must include a tiered set of surface, airborne, and satellite sensors. We present a vision, strategy, requirements, and roadmap for an international framework to assess directly the carbon emission trends of the world's urban areas and megacities. We discuss the LA Megacities Carbon Project as an example of a testbed for developing and validating multiple observational techniques ranging from continuous in-situ analysis to geostationary and polar orbiting sounders to mobile boundary layer profiling.