The nickel famine
A cooling mantle starves methane-making microbes of a trace metal, and the greenhouse begins to fail.
- When
- Known to
- ± 100 million years
- Era
- Neoarchean, Archean
Methanogens depend on nickel-bearing enzymes, and nickel reached the oceans mainly through eruption of magnesium-rich komatiite lavas. As the mantle cooled and komatiites ceased, dissolved nickel fell sharply through the late Archean. Starved methanogens produced less methane, weakening the haze that had been suppressing oxygen accumulation. It is one leading explanation for why oxygen finally broke through when it did, hundreds of millions of years after cyanobacteria evolved.