Mass Extinctions and Carbon Dioxide

The evidence that the Earth's "Big Five" extinction events were triggered by the enormous volcanic events that created the so-called Large Igneous Provinces (LIPs) continues to accumulate. The most catastrophic of these, the end Permian extinction, killed most of the species that existed at the time. It was long suspected that it was tied to the epic Siberian Traps volcanism (think many millions of Mount Saint Helens eruptions) and new geochronological evidence makes the evidence of simultaneity far more precise.

So why were these eruptions, which large as they were, were confined to relatively small portions of the globe, so catastrophic for the whole planet? The big culprit seems to have been carbon dioxide, with an assist from sulfur dioxide. The sulfur dioxide caused as sharp global cooling, lasting only a few years, and extreme acid rain. The CO2 triggered multi-millenium long global warming and ocean acidification, producing anoxic oceans that killed most sea life. The weather likely sucked too, perhaps including the enormous hypercanes (super powerful hurricanes).

The other big extinction events are also tied to the formation of large igneous provinces, though the timing is less precisely tied down. Even the end Cretaceous extinction event, usually associated with the impact that created the Chicxulub crater, is closely associated with the formation of the Deccan Traps LIP. The impact may have either accelerated the LIP or just provided another major aggravating factor. All of the other mass extinctions show the same big CO2 pulse.

Other evidence shows that warm periods in the Earth's history are associated with less spectacular instances of unusually widespread volcanism, again with CO2 as the executive agent.

At the risk of being tedious, one more sign that we are on a disastrous course with our own experiment in massive CO2 release.

Comments

Post a Comment

Popular posts from this blog

Anti-Libertarian: re-post

The most pointed critique of social security and liberalism in general is the libertarian critique. The problem with libertarians, for a liberal, is that we have too much in common. We both believe in individual rights, tolerance of individual differences, and dislike government prescription of religion. The basic difference, it seems to me, is the different answers we give to Cain's (with thanks to the Captain - my original version had the corpse asking the question!) famous question: "Am I my brother's keeper?" That's not really my basic bitch against the libertarians though. My real complaint is the same as my complaint against most religion - its premise is a fraud. For those who can't stand to wait for the punchline, I believe that trying to implement libertarian principles leads to tyranny or social disintegration. Demonstrating that takes some historical (and pre-historical) context. For all but the last 15,000 or so of the 100,000 years the human spec
Read more

Uneasy Lies The Head

Uneasy lies the head that wears a crown ........... Shakespeare Henry IV, Part II. So it is with us and our slightly distant primate cousins , so it seems. A 9-year study of wild baboons in Kenya by Princeton University and the Institute of Primate Research may turn conventional assumptions of alphas males upside down. The study found that alpha males have high testosterone levels, which allows them to dominate other baboons, get access to more food, and attract better mates. This is expected. Surprisingly, though, the alpha males also have high levels of stress hormone glucocorticoid, which scientists measured from their feces samples. In fact, the stress of alpha baboons was on par with low-ranking baboons. The convention wisdom is that access to food and females provides life security and thus less stress for dominant males. Conversely, weak males who are constantly threatened by starvation and physical violence from stronger males are thought to be more stressed. The st
Read more

We Call it Soccer

The US played its best, and maybe only good game of World Cup, but lost thanks to brilliant goalkeeping by the Swedish keeper and the bizarre method soccer uses to settle ties when three US stars could not put the ball on frame from the 12 yard spot.  At the end it came down to a blocked shot that spun in by maybe a couple of centimeters. Well, that's football - too much like life.   Which brings me to a modest proposal.  Replace the thirty minute overtimes with as many 7-player 15 minute periods as needed to settle it.  Scoring should be much easier with fewer players.
Read more