I almost made this post. I mean really I think I typed this.
Anyway, it turns out volcanoes are useful in other ways: Link@The Guardian
I take this as evidence of the closed circuit idea. Earth is a single biosphere on some level. Evolution has ways of countering the effects of the Earth (call it Mother Nature, Gaia, or geological formation). When the environment was too heavy with CO2 for life to come ashore, plants took over. Most land animals breathe oxygen, while plants breathe our waste product CO2. I think its funny that even though the volcano belched out this huge cloud of CO2, it actually drastically reduced the amount of CO2 contributed to the atmosphere for a period of some days by way of the airplane groundings.
They also look cool which is something earthquakes don't really have going for them.
