Friday, April 25, 2008

Volcanoes, climate change and politics

A child born in Europe in 765 AD would have lived to the ripe old age of 55 without experiencing a single severe winter to threaten his food supply and economic system. A child born in 763 might not have made it through the first winter. A child born in 820 AD would have five such crisis winters to live through. Volcanoes which brought on rapid climate change which brought on famines and eventually the "little ice age" are the topic of this interesting study in a recent issue of Speculum, the journal of the Medieval Academy, "Volcanoes and the Climate Forcing of Carolingian Europe, A.D. 750-950," By Michael McCormick, Paul Edward Dutton and Paul A. Mayewski.

So what happens when there is a lot of volcanic activity, as there was after a lull in the first 500 years of the Christian era?
    Microscopic particles, if lifted into the stratosphere as an aerosol—solid or liquid particles suspended in a gas, in this case, the atmosphere (e.g., a cloud)—may diminish the global temperature by blocking solar radiation. This in turn will work various and complex effects on atmospheric and oceanic circulation. Furthermore, volcanic aerosols increase nucleation sites for water. The resultant cloud condensation nuclei can produce precipitation. Volcanic emissions are typically rich in sulfur dioxide (SO2), which is converted to sulfuric acid (H2SO4). In addition to reflecting solar radiation back into space and thereby cooling the earth, the aerosols also fall to the earth. The resultant sulfate (SO4) particles are preserved in the millennial record of atmospheric deposits—snow—in the great Greenland glaciers, and, through mass spectroscopy, the particles can be measured in parts per billion (ppb) in the annual layers of ice.
The authors suggest that Charlemagne may have been more lucky than smart, and his son just got dealt a bad hand by the weather. "His act of public penance would have little effect on the volcanic aerosol that produced yet another terrible winter, famine, and disruption but a year later." Obviously, politics and weather went hand and glove even 1300 years ago--Kyoto and the UN fiddling isn't new.

The thought occurred to me that maybe God was at work getting the church established by quieting down the volcanoes in the early years of the church; and now natural and atmospheric events have been loosed--but former and current presidents want to believe otherwise.

1 comment:

Anni said...

Your blog link must have been deleted in error. I'll go re-add it to the bloggers over 50 blogroll right now.

Thanks for letting me know.