The inception of the "Keeling Curve," a history of atmospheric carbon dioxide levels, marked a key moment in American science history. The record began in March, 1958 at a small observatory on the top of Hawaii's Mauna Loa.

Biological activity in the oceans might make the difference between clear skies and cloudy, Scripps researchers say.

An ancient global warming episode drastically changed the planet. Life on Earth needed 200,000 years to recover. What we're headed for in the next century could be even bigger.