Massive Changes in Oceanic & Atmospheric Circulation Triggered Ancient Global Warming

The planet’s climate systems is nothing really but a large game of dominoes, with one consequence or event always linked or linking to another, continuing down a chain. The formation of the Atlantic Ocean, in particular its northeast corner, may have been one in a line of dominoes that created a planetary global warming some 55 million years ago.

At the end of the Paleocene epoch, an event took place which has gone down in history as the Paleocene–Eocene Thermal Maximum. It was a time of great planetary warming, and is associated with massive changes in oceanic and atmospheric circulation, the extinction of 30 to 50 percent of sea floor life, and the turnover of mammalian life.

According to Michael Storey, a geochronologist at Roskilde University Center in Roskilde, Denmark, this global warming was caused by the baking of carbon-rich sediments that were suddenly introduced to a large amount of molten rock and heat thanks to the rifting apart of the Earth’s crust which created what we now know as the North Atlantic.

Storey’s theory does not blame the entire crash of fauna on the appearance of the North Atlantic, but rather lays at its feet the beginning – or maybe the continuation – of the game of dominoes that is our planet’s climate.

With the sudden introduction to molten rock and heat, the carbon-rich sediments expelled several hundred giga-tons of greenhouse gasses in to the atmosphere. Storey believes that, in turn, these greenhouse gasses warmed the oceans just enough to thaw masses of frozen methane which then bubbled to the surface and added their own weight to the continuing change.

At the height of the Paleocene–Eocene Thermal Maximum (PETM), sea surface temperatures in the tropics rose 5 degrees C and 6 degrees C in the Arctic. The 30 to 50 percent sea-floor extinction mentioned above was due to a massive and sudden increase in sea level acidity.

"The two outstanding questions about the event are what triggered it and where did all the greenhouse gases come from," said Storey, who’s paper on the matter appear in the April 27 issue of the journal Science.

To answer the first question, Storey and his colleagues Robert Duncan and Carl Swisher collected volcanic rock specimens from the edges of what was once a united Denmark and Greenland. They used a natural clock in the minerals to date the rocks and see whether their age matched up with the PETM, and found that they were of the approximate same age.

"The dating allows us to link the (PETM) to what we see as a massive surge of volcanic activity," Storey told Discovery News. And according to paleo-oceanographer James Zachos of the University of California at Santa Cruz, "This is almost perfect because you have that as a trigger," because "the system is just perched on the edge and you just need a little kicker."

As a matter of relating this science to today, today’s estimates put between 2,000 and 10,000 giga-tons worth of methane hydrates buried away in cold ocean sediments. By way of comparison, humans currently release between six and seven giga-tones of carbon in to the atmosphere each year. No one is quite sure just how much the planet has to warm up before those methane hydrates get loose, but you can guarantee you don’t want to be around when they do.

Posted by Josh Hill.

http://dsc.discovery.com/news/2007/04/26/magmatrigger_pla.html?category=earth&guid=20070423094530

Comments

[Fremon Sandlewould]

Yes I think the penguins are depenguining on us. We must put windmills on our cars to generate electricity with the wind that occurs when driving. Problem solved!