Of carbon and mega-cities

Los Angeles and Paris are serving as guinea pigs for an emerging global effort to track the carbon footprints of cities with more than 10 million people.

As worldwide levels of carbon dioxide reach unprecedented recorded levels—a Hawaii measuring station recently recorded the benchmark CO2 concentration of nearly 400 parts per million—scientists are looking to mega-cities they believe are increasingly responsible for climate change, according to SFGate.com.

High-tech sensors mounted at points overlooking Paris and L.A. have been installed in hopes of determining whether localized efforts (like switching buses from diesel to alternative fuel) have made a significant dent in greenhouse-gas emissions, and that the cities are on the right course to meet self-implemented climate goals.