Atmospheric CO2 hits ominous milestone
'I honestly think we're already in dangerous territory,' researcher says
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.