January 7, 2013
How the Early Earth Avoided a Deep Freeze
Scott Johnson, Ars Technica
Although life seems to have gotten a quick start on it, the early Earth was a nasty place. Very early on (and perhaps again later), meteors frequently peppered the surface. The atmosphere contained no oxygen, and consequently no ozone, to shield the surface from UV radiation.
TAGGED: nitrogen, hydrogen, greenhouse effect, ice age