I already wrote a few articles on dark skies and light pollution. It seems the phenomenon is even worse as one can see with the image on left (courtesy of Stellarium, a great astronomy freeware)
This also has an important impact on greenhouse gases emissions. In Australia alone, public lightning is responsible for 1.15 million tonnes of CO2 emissions each year. I guess it’s high time to install more efficient lights in our streets.
Barcelona have a great idea that should be replicated all around the world. This way, streets would be lit only when needed and with energy efficient lights. This would reduce consumption by 30 percent.