[tgarv]

I was actually wondering recently if there has ever been a huge spike in, say, a new species of algae or something, that caused a large change in the atmosphere. I know that what we're doing as a species isn't "natural", and we know better and could avoid it if we really wanted to, but it still had me thinking about what kinds of things the planet has gone through before that would have been alarming at the time if someone had been around to monitor it.

[AprilArcus]

The Azolla Event (https://en.wikipedia.org/wiki/Azolla_event) was a cyclical bloom of duckweed-like ferns in the Arctic Ocean about 49 million years ago which drew down atmospheric CO2 by an order of magnitude, from 3500 ppm (responsible for the warm, verdant climate you think about when you imagine the Mesozoic era) to 650 ppm (responsible for the cold, cyclical glaciations you think about when you imagine the modern world), and in which vicinity it has remained ever since.

[saagarjha]

(FWIW, atmospheric carbon dioxide levels pre-Industrial Revolution were about 280 ppm, and today are just over 400 ppm.)

[Donald]

Species are created on geologic timescales. Human activity is, in comparison, instantaneously destroying biological diversity. Evolution simply doesn't have enough time to adapt species to the sort of exponential changes we're seeing in their environments.

[frutiger]

Evolution is like gravity. It doesn’t have to adapt to anything on any timescale that is important to our anthropological ideas of “change” or “environment”.

[Scarblac]

The Great Oxidation Event (https://en.wikipedia.org/wiki/Great_Oxidation_Event) was exactly that. Oxygen-producing organisms caused the extinction of almost all life, over two billion years ago.