415: The Most Dangerous Number
By Jeff Goodell
415.26 parts per million: CO2 levels hit historic high
By Patrick Galey
Carbon dioxide hits a level not seen for 3 million years. Here's what that means for climate change — and humanity.
By Denise Chow
CO2 in the atmosphere just exceeded 415 parts per million for the first time in human history
By Jonathan Shieber
Climate change: CO2 levels hit 415 parts per million in human first
By Ryan W. Miller & Doyle Rice