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20 December 2009

Site history

I recently came across the following statement in a forum:

"As a matter of interest there is a volcano in southern Chile that is burping and belching millions of tons of ash, carbon dioxide and debris into the air. In two weeks it has spit out more CO2 (Carbon Dioxide) than the sum total of all human activity has in more than two decades."

This statement, written by a man from Nottingham, England, seemed so outrageous that I felt constrained to check whether there was an element of truth in the carbon dioxide emissions. I have seen several similar posts in forums stating that carbon dioxide from volcanoes was greater in quantity than man-made emissions. As I instinctively felt that the presence of carbon or carbonates in magma could not be great, I had my doubts about the veracity of it. However, I'm no vulcanologist, so I had little knowledge to start with and felt that I had to check my feelings. So, I did what most people would do, a Google search.

My first research was to try and find out which volcano was concerned. I searched initially under volcano chile eruption, producing some 1,700,000 references. From this, I found two volcanoes had erupted there in the past two years, Chaiten in May 2008 and Llaima in April 2009. Taking the most recent first, I tried finding web sites from the scientific community. The first one I came across was a NASA report which was not over-helpful, "...the volcano’s activity increased on April 2, accompanied by water-vapor emissions.". No mention of other gases. Other serious sources were no more helpful. Even media sources would state, '"During the night, the volcano maintained its activity with explosions, lava flows, and expulsions of gas and ash," ONEMI [State National Emergency Office] said.' At least, this mentioned gas, without specifying its nature. It appeared that this eruption, although serious, was not really what one would call major.

The Chaiten eruption, on the other hand, was major - and a surprise, as it was dormant for about 9,000 years. Geology.com reported, "When the volcano began erupting in May 2008, it produced high Plinian eruption columns of ash, gas and rock. These columns were accompanied by pyroclastic flows, lahars, and abundant ashfall." Not much more helpful in respect of what the gas composition was.

So far, I found nothing that supported the statement about carbon dioxide emissions. I started to look outside Chile about the composition of emitted gases.

The next site I found with useful information was from the United States Geological Survey (USGS). On the index page it states, "At high pressures deep beneath the earth's surface, volcanic gases are dissolved in molten rock. But as magma rises toward the surface where the pressure is lower, gases held in the melt begin to form tiny bubbles ... Together with the tephra and entrained air, volcanic gases can rise tens of kilometers into Earth's atmosphere during large explosive eruptions. ... The gases spread from an erupting vent primarily as acid aerosols (tiny acid droplets), compounds attached to tephra particles, and microscopic salt particles." This seems more positive, but is it the whole story? Elsewhere, the USGS mentions the pollution caused by sulfur dioxide emissions from Kilauea Volcano in Hawaii, but sulfur dioxide has the opposite effect to carbon dioxide. It is the basis of sulfate particles that actually reduce solar radiation reaching the earth's surface. It therefore has a "global cooling" effect. Still no mention of carbon dioxide.

Another site I came across, although not scientific, stated:

Carbon dioxide (CO 2 )

Volcanoes release more than 130 million tonnes of CO 2 into the atmosphere every year. This colorless, odorless gas usually does not pose a direct hazard to life because it typically becomes diluted to low concentrations very quickly whether it is released continuously from the ground or during episodic eruptions. ... 

At least we have some information here but can we substantiate this figure of 130 million tonnes? If so, we can say the emissions are almost negligible, representing less than 0.5% of emissions from global burning fossil fuels, about the same as a sparsely-populated developing nation, such as Algeria. Wikipedia did not help, although it said, "The abundance of gases varies considerably from volcano to volcano. However, water vapor is consistently the most common volcanic gas, normally comprising more than 60% of total emissions. Carbon dioxide typically accounts for 10 to 40% of emissions." This, by itself was not really helpful, as it does not substantiate the figure. Although I mistrust Wikipedia as a definitive source of information, this quotation was referenced to a book. A 1997 paper stated, "Volcanoes contribute about 110 million tons of carbon dioxide per year while man's activities contribute about 10 billion tons per year.", so this is in the same ballpark as the figure given earlier. Of course, the 10 billion tonnes is much lower than today's reality. The paper in question was written by the late Richard V. Fisher who was one of the world's leading vulcanologists and was professor emeritus in geology of the University of California, Santa Barbara, so I think we are now on the right track with substantiated data.

A little further research found the source of the 130 million tonne figure and it is, indeed, scientifically credible. The quotation above is copied textually from this USGS page and comes originally from: Gerlach, T. M., Delgado, H., McGee, K. A., Doukas, M. P., Venegas, J. J., and Cardenas, L., 1997, Application of the LI-COR CO2 analyzer to volcanic plumes: A case study, Volcan Popocatepetl, Mexico, June 7 and 10, 1995: Journal of Geophysical Research, v. 102, p. 8005-8019. and subsequent work and published papers by Dr T.M. Gerlach of the USGS.

Why now?

Volcanoes have erupted since time immemorial, if I may use a cliché. Why, then, have climate change deniers suddenly started to cite them as a major cause of the increase in atmospheric carbon dioxide levels over the past 50 years or so? In the last 7000 years, there have been 12 major eruptions, far exceeding any that have occurred in the last 90 years. Ice cores and tree growth have shown no evidence of significantly increased carbon dioxide levels, although volcanic ash and dust (ejecta) have been found from them. The following table has been adapted from this site, the ejecta being measured in km³. These major eruptions did not emit sufficient carbon dioxide to significantly increase atmospheric levels. At least two of them caused historically documented global cooling over a few years, due to dust and sulfate aerosols projected into the upper atmosphere.

Conclusion

Volcanoes do not emit carbon dioxide in quantities sufficient to increase the global levels in a significant manner. Furthermore, no eruption over the last 90 years has been sufficiently catastrophic to have been likely to do so. Major eruptions project reflective dust and sulfates into the lower stratosphere and upper troposphere; these may lower temperatures on a global scale over 2 to 5 years,

Source of the rumour

I tried to find out where this idiotic rumour started. This is not easy. There are plenty of vague references about carbon dioxide emissions and volcanoes, most of them more ridiculous than the others. The earliest reference I could find with something like the text of my quotation is in a blog "Chilian Volcano Has Belched more Carbon Dioxide Than all Humans Have in Last two Decades.". This was published by one Richard Cochrane on 16 June 2008. His web sites include richardcochrane.hypocrisy.com, hypocrisy.com, hypocrisy.superblogs.com, richardwcochrane.com and, I suspect, several others. He claims to be an expert in hypocrisy, economics, environment, humanities, politics, race, health, religion, lifestyle, entertainment, holidays, sports and possibly more, as his blog site says, "He is trained in chemistry and metallurgy but is far more interested and practiced as a political and fund raising consultant, writer and amateur historian." Truly a Jack of all trades and master of none, it would appear. In the context of this page, he quotes no references to substantiate his haverings.