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Q: Could it really be true that a single large volcanic eruption launches more greenhouse gases into the atmosphere than the amount generated by all of humanity over history? (http://features.csmonitor.com/environment/2009/02/06/which-is-the-bigger-polluter-%E2%80%93-humans-or-volcanoes/)

http://www.cleanmpg.com/photos/data/506/volcano-1.jpgSteve Schlemmer - CSMonitor – Feb. 06, 2009

At 200 million tons of carbon dioxide emitted per year by volcanoes, they pale in comparison to the automotive industry’s. -- Ed.

Q: Could it really be true that a single large volcanic eruption launches more greenhouse gases into the atmosphere than the amount generated by all of humanity over history?
– Steve Schlemmer, London

A: The argument that human-caused carbon emissions are merely a drop in the bucket compared with greenhouse gases generated by volcanoes has been making its way around the rumor mill for years. And while it may sound plausible, the science just doesn’t add up.

According to the US Geological Survey, all the world’s volcanoes – on land and undersea – generate about 200 million tons of carbon dioxide (CO2) annually, while our automotive and industrial activities create some 24 billion tons of CO2 emissions every year worldwide. Those facts speak for themselves: Greenhouse gas emissions from volcanoes are less than 1 percent of those generated by today’s human endeavors.

Another indication that human emissions dwarf those of volcanoes is the fact that atmospheric CO2 levels, as measured by sampling stations around the world set up by the federally funded Carbon Dioxide Information Analysis Center, have… http://features.csmonitor.com/environment/2009/02/06/which-is-the-bigger-polluter-%E2%80%93-humans-or-volcanoes/

One of the worst, or the worst ecological disaster was caused by the "Siberian Traps" massive volcanic eruptions.

http://articles.latimes.com/2005/jan/21/science/sci-extinct21

Most life on Earth went extinct.

Sulfur spewed out by volcanoes in the so-called Siberian Traps depleted oxygen in the air while creating powerful greenhouse gases that trapped sunlight and raised the Earth’s temperature sharply, producing the event known as the “Great Dying.”

“It got hotter and hotter until it reached a critical point and everything died,” said paleontologist Peter D. Ward of the University of Washington, lead author of one of the two papers published online by the journal Science.

“It was a double-whammy of warmer temperatures and low oxygen, and most life couldn’t deal with it.”

Global temperatures probably rose about 18 degrees Fahrenheit, Ward said, killing off many of the relatively primitive plants that served as a food base for land animals.

At the same time, the proportion of oxygen in the atmosphere dropped from the normal level of about 21% to as low as 16%, a change that is equivalent to climbing to the top of a 14,000-foot mountain.

“High and intermediate elevations would have become uninhabitable,” he said. “More than half the world would have been unlivable. Life could only exist at the lowest elevations.”

Harry

From the article cited in the original post:


In an interesting twist on the issue, British researchers last year published an article in the peer-reviewed scientific journal Nature showing how volcanic activity may be contributing to the melting of ice caps in Antarctica – but not because of any emissions, natural or human-caused, per se.


Scientists Hugh Corr and David Vaughan of the British Antarctic Survey believe that volcanoes underneath Antarctica (http://www.newscientist.com/article/dn13205-first-subglacial-eruption-found-in-antarctica.html) may be melting the continent’s ice sheets from below, just as warming air temperatures from human-induced emissions erode them from above.

One of the worst, or the worst ecological disaster was caused by the "Siberian Traps" massive volcanic eruptions. ...

At the same time, the proportion of oxygen in the atmosphere dropped from the normal level of about 21% to as low as 16%, a change that is equivalent to climbing to the top of a 14,000-foot mountain...

I wonder how this is figured. A back-of-the-envelope calculation, backed up by a quick web search, indicates that 16% oxygen at sea level has the same oxygen partial pressure as 21% oxygen at 7,000 feet. Absent other chemistry changes, this is quite survivable.

I had never heard of the "Siberian Traps" until I saw a program on TV about it.

Another web site with information:
http://www.ens-newswire.com/ens/mar2006/2006-03-13-05.asp

As the levels of atmospheric oxygen fell and the levels of hydrogen sulfide and carbon dioxide rose, the upper levels of the oceans could have become rich in hydrogen sulfide. Kump says this would kill most the oceanic plants and animals and the hydrogen sulfide dispersing in the atmosphere would kill most terrestrial life. "A hydrogen sulfide atmosphere fits the extinction better than one enriched in carbon dioxide," says Kump. "Carbon dioxide would have a profound effect on marine life, but terrestrial plants thrive on carbon dioxide, yet they are included in the extinction."

Another piece in the puzzle surrounding the end-Permian extinction is that hydrogen sulfide gas destroys the ozone layer. Recently, Dr. Henk Visscher of Utrecht University and his colleagues suggested that there are fossil spores from the end-Permian that show deformities that researchers suspect were caused by ultraviolet light.

"These deformities fit the idea that the ozone layer was damaged, letting in more ultraviolet," says Kump.

Once this process is underway, methane produced in the ample swamps of this time period has little in the atmosphere to destroy it. The atmosphere becomes one of hydrogen sulfide, methane and ultraviolet radiation.

Harry

PS: the Ozone Layer has been damaged by human-produced aerosols released into the atomosphere, mostly chorine compounds. This is another reason we all need to be more careful about sun exposure and skin cancer. I lost a friend of mine recently to melanoma, and I've had skin cancer 3 times due to overexposure from working outdoors.