'Dangerous Territory': Carbon Dioxide Levels Reach Milestone

Pat Lang, of NOAA in Boulder, Colo., measures the amount of greenhouse gases from an air sample. The Boulder lab is part of a global network of air-sampling laboratories that track carbon dioxide levels in the atmosphere.
Pat Lang, of NOAA in Boulder, Colo., measures the amount of greenhouse gases from an air sample. The Boulder lab is part of a global network of air-sampling laboratories that track carbon dioxide levels in the atmosphere.