Volcanic Warming Eyed in 'Great Dying'

gollum123 writes "AP writes on an article in the journal Science where an ancient version of global warming may have been to blame for the greatest mass extinction in Earth's history. 'In an event known as the "Great Dying," some 250 million years ago, 90 percent of all marine life and nearly three-quarters of land-based plants and animals went extinct. Researchers think the answer is Massive volcanic flows in what is now Siberia, and believe the extinctions were caused by global warming and oxygen deprivation over long periods of time."

Comments

Yesterday we had the great freeze...

[bwcarty]

now we have the great dying.

This bit o' work by Robert Frost seems appropriate now:

Some say the world will end in fire,
Some say in ice.
From what I've tasted of desire
I hold with those who favor fire.
But if it had to perish twice,
I think I know enough of hate
To say that for destruction ice
Is also great
And would suffice

Slashdot...News for Nerds. Stuff about death.

Ok, I RTFM...

[His name cannot be s]

From the article:
Studying a 1,000-foot thick section of exposed sediment, Ward's team found evidence of a gradual extinction over about 10 million years followed by a sharp increase in extinction rate that lasted another 5 million years.

Huh?

A Gradual extinction over 10 million years? Yeah, That's gradual all right.

The best part is the "sharp" increase over five million more years. So what he's saying is that a hell of lot of stuff died over 15 million years? Wowfuck.

If we've got 10 to 15 million years of fossil fuel to burn, I say screw it.

"Dear? you can turn up the heat now"

feh.

Change in oxygen levels

[dragons_flight]

It is not obvious to me that changing oxygen levels would be all that destructive. We've known for a while that oxygen levels in the Triassic (following the "Great Dying") where some of the lowest in Earth's history. We have also known that oxygen concentration in the Carboniferous (50-100 Myr earlier) were some of the highest (perhaps 180% of modern value).

In the Carboniferous, what you see (in addition to extra nasty forest fires) is an explosion of gigantism among diffusion limited organisms. Such organisms, mostly insects and amphibans, have respiratory or circulatory systems that are limited by the ability of oxygen to diffuse through them. With higher O2 levels, such animals can develop larger body plans and clearly did in the Carboniferous. By contrast, falling O2 levels would probably be an evolutionary pressure towards dwarfism and smaller body plans.

After the Permian mass extinctions, we do see very few large animals. This might be associated with low O2 levels, but it might also be the results of an ecosystem so disrupted that it can't support large predators.

However, it would be hard to hang the extinctions on oxygen alone since oxygen levels seem to have fallened over a much longer period of time than the extinctions, and would not have affected all organisms equally. Perhaps coupled with volcanism and global warming it is enough, but personally I doubt it. I am inclined to favor models that talk about volcanism or other causes leading to stratification and toxicity in the oceans. If you are going to kill >90% of all oceanic species, it would seem that the best bet is to make the oceans unlivable for them.

However, this debate is likely to continue for a long time and we will no doubt hear many other theories before it is all done.

Humans could deal with 10%

[Engineer-Poet]

There are human populations living at altitudes where the partial pressure of oxygen is about half that at sea level (Peru, Tibet). Even more interesting, the two populations seem to have two different adaptations to the altitude and there may be another adaptation original to Ethiopia. I doubt that we'd have any difficulty engineering ourselves with the physiological changes required to handle such conditions even if they occurred over the next century.

The rest of the ecosystem would probably not be so flexible.