Early Plants May Have Caused Massive Glaciation

sciencehabit writes with this excerpt from Science: "The first plants to colonize land didn't merely supply a dash of green to a drab landscape. They dramatically accelerated the natural breakdown of exposed rocks, according to a new study, drawing so much planet-warming carbon dioxide (CO2) from the atmosphere that they sent Earth's climate spiraling into a major ice age."

Comments

Peter Wards "Medea hypothesis"

[peter303]

The Medea hypothesis is the mirror of the Gaia hypotheis. Gaia says life is in ecological balance and self-balancing.

Part 1 of the Medea hypothesis says that life isnt necessarily in ecological balance and sometimes overruns resources nearly killing itself off. Several past mass extinctions, particularly the Permian may have been caused by this.

Part 2 says the ultimate end of life on Earth may be running out of CO2. CO2 has been falling from tens of percent on the early Earth to about one percent in the Phanerozoic to .025% now. (Human activity has temporarily raised it to .04%.) When CO2 falls below .01% then plants cannot survive and neither animals. Just bacteria. This is predicted in few hundred million years. Life consumes CO2 and buries in hydrocarbons and limestone. Unless some imbalance like humans come along, the trend is to pretty much lock up carbon for good.

Geo-engineering CO2 increase is straight forward. Burn limestone to release CO2. There is 100x more carbon in limestone than hydrocarbons.

Re:Peter Wards "Medea hypothesis"

[DeathFromSomewhere]

Volcanoes release massive quantities of CO2 into the atmosphere that was previously locked up in limestone. In fact the CO2 released by volcanoes is the main reason snowball earth came to an end.

Re:Peter Wards "Medea hypothesis"

[ElectricTurtle]

I suppose you think the ocean has been the same pH forever too. Life adapts, and ocean life itself has shown an ability to spring back from as much as 90% species extinction. I'm not worried, especially as humans have the technology to build closed systems for environmental control and resource production/management. (Humanity too has sprung back from an immensely small population, as low as thousands at one point. We could lose 99.99999+% of our population and still have precedent for survival.)

The truly ironic thing is that people will now jump up my butt about how cold I am and what about all those people who might die. The same critics who, in a different context would be whining about overpopulation. Let me break it to you, the only way it is physically possible to have less people is for them to die. There is no magical fairy dust that makes population lower without people pushing up daisies. The cognitive dissonance is staggering.

(The double irony is that overpopulation is itself a myth, and anybody who knew anything about the real demographic data that shows that fertility rate has been on a downward rollercoaster for something like fifty years in almost every nation on earth. Population growth is leveling off, but that doesn't sell newspapers.)

Re:Peter Wards "Medea hypothesis"

[GameboyRMH]

So you'd prefer many human deaths, oceanic mass extinction and living in sealed dome environments to being more eco-friendly, and call anyone who thinks being more eco-friendly is a better solution a stupid alarmist.

Maybe you should lock yourself in a room of pure CO2. After all, carbon is life itself, and I guarantee you no stupid alarmists will follow you in.

Re:And this is how bad memes get started

[icebike]

The phrase "at the height of" means "the beginning of the end."

I'd be more interested in knowing what the deepest cores show, from the beginning of the last ice age. If they were similarly high, then your question is insightful.

If however the co2 peeked sometime within the ice age, and that was followed by the decline of the ice age we have an interesting coincidence, but still no causation.

The question then becomes where did this co2 come from. Did it come from the much reduced plant intake of co2 due to having significant areas of the planet in a deep freeze? Were the oceans chilled enough such that marine organisms ceased sequestering co2 into reefs?

Or was there some as yet undocumented sources of co2 that were ramping up production?

Or was the output of the sun reduced during this period and any suggestion about co2 merely mistaking the effect for the cause?