The �Volcano Question� is a good one. Much of the information floating about seems heavily influenced by personal bias or by who happens to be funding the study. I suggest two documents as helpful:
http://plaza.ufl.edu/airwess/
http://climate.envsci.rutgers.edu/pd...ThePlanet2.pdf
They have a spin, but are informative. The gist of these and other sources, plus my geology classes and industry experience, seems to be that we live on a planet that is dynamically changing and totally indifferent to our existence and mostly unaffected by our efforts. The biological component of the planet scrambles and reacts to the planet�s physical changes by either adapting or dying. It would seem that volcanism is responsible for creating our atmosphere and has changed the atmosphere�s composition over time. That change is ongoing and is still underway. Our admittedly shallow database of measurements seem to indicate that climatic changes induced by a single eruption from carbon dioxide and ash are significant but relatively short termed (2-6 years, depending on the source). The emissions of sulphur compounds and other materials are less well understood. Apparently the gross emissions of sulphur dioxide from eruptions are only 15% of man-made emissions. That number is shaky and there are natural sources other than explosive eruptions. Perhaps more important is where the injection of the SO2 occurs. Much of the volcanically generated SO2 occurs at high enough altitudes to have an impact out of proportion to its volume. Also, I know that in drilling for oil and gas we use layers of ash at different depths as markers to aid in telling where we are relative to certain target zones. Some of these as layers are local, covering only a few states. At least one is found world-wide. In the end, our climate and weather are driven by that overwhelming engine of heat, the sun. That is as true on Venus, with a sulphurous atmosphere, as it is on Earth or Jupiter. The composition of that atmosphere is a product of the planet itself.
Anyway, I think that our activities have some impact but that over time they are overwhelmed by natural processes (unless we do something really silly; nuclear war, anyone? Even that will disappear over geologic time). Perhaps even more interesting is the clustering of major volcanic and meteor activity at the great extinction events in history, particularly the Paleozoic-Mesozoic and Mesozoic-Cenozoic boundaries. Most people don�t realize that 60% of all known species became extinct at the Paleozoic-Mesozoic boundary. A company called Pan Terra produces a fabulous wall chart titled �A Correlated History of the Earth� detailing the evolution of animal and plant life, plate tectonics, and volcanic and meteor activity.
Another comforting thought: the Galactic Drift theory has us due for a meteor/comet strike and another massive die-off�.
Edit for grammar.
[ February 13, 2004, 18:45: Message edited by: solops ]
Re: more scary stuff
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