A methane-hazed sky
Methanogens fill the air with methane, and Earth is wrapped in orange smog.
- When
- Known to
- ± 100 million years
- Era
- Neoarchean, Archean
With no oxygen to destroy it, biological methane accumulates to perhaps a thousand times modern levels. Ultraviolet light turns some of it into an organic haze of hydrocarbon particles, tinting the sky orange and shielding the surface from radiation while cooling it slightly. The methane greenhouse is probably what kept the planet habitable under a faint Sun — and its eventual destruction by oxygen is what triggers the first great glaciations.