Atmospheric CO2 hits ominous milestone

Duncan McCue has the story of the Keeling curve, considered by some to be one of the greatest achievements of modern science, which documents the rise in carbon dioxide in the Earth's atmosphere.

'I honestly think we're already in dangerous territory,' researcher says

Duncan McCue visits an observatory that was set up 5 decades ago to measure carbon dioxide levels 8:23

Dave Keeling was a California chemist who in the 1950s had a theory that industrial emissions of carbon dioxide weren't all being absorbed in the sea.

To test his theory, Keeling set up a station atop a Hawaiian volcano known as Mauna Loa to measure carbon dioxide in the Earth's atmosphere in a simple but precise way.

CBC's Duncan McCue reports that the data collected over the decades has now hit a key milestone.