Common Scents

High atop Mount Wilson sits a Panchromatic Fourier Transform Spectrometer. It is tracking the carbon dioxide in Los Angeles's air by its smell. There are Spectrometers in Paris, now, and São Paolo, too, and the goal is to have them in 40 cities worldwide to track the trends of one of the major causes of climate change (video): http://www.weather.com/video/smelling-los-angeles-35989