calderas and hurricanes

[Downdraft]

A caldera volcano is a "super volcano." And, yes a volcanic eruption of that magnitude could trigger an ice age. The average volcano ejects enough green house gases, particularly sulphur dioxide, to affect world temperatures. Normally, that affect is insignificant, however, if Yellowstone erupted you could kiss the vast majority of the west good-bye and it would lead to a climatic changes that could trigger an ice age. Yellowstone will erupt again the question is how much of the magma that sits under it is eruptable and ejectable. The answer to that question could well determine the fate of mankind.

[milankovitch]

A caldera volcano is a "super volcano." And, yes a volcanic eruption of that magnitude could trigger an ice age. The average volcano ejects enough green house gases, particularly sulphur dioxide, to affect world temperatures. Normally, that affect is insignificant, however, if Yellowstone erupted you could kiss the vast majority of the west good-bye and it would lead to a climatic changes that could trigger an ice age. Yellowstone will erupt again the question is how much of the magma that sits under it is eruptable and ejectable. The answer to that question could well determine the fate of mankind.

A supervolcano produces a caldera but not all calderas are produced from supervolcaoes. For instance Krakatoa, and Santorini produced calderas while these were large eruptions they weren't supervolcanos. The Supervolcano term is usually used for 1000km3 eruptions. Even Kilauea has a caldera. They can be created by explosive or non-explosive means; caldera just means surface subsudance caused by a magma chamber being emptied.

Also, sulphur dioxide is not a greenhouse gas, and most volcanos do not put out substantial amounts of CO2. Human CO2 emission exceeds volcanoes by about a factor of 100 each year. Now a trend in volcanism over millions of years like increased Pacific volcanism in the Cretaceous can raise CO2 and effect global climate. Now, something on the scale of a supervolcano maybe but probably more along the lines of the Deccan Traps (500X larger) would put a substantial amount of CO2 into the atmosphere. (I have a book on Cretaceous geology so I'll have to check if a supervolcano would) Sulpur dioxide and water produces sulphuric acid aerosols (tiny droplets) which can stay in the stratosphere for several years. I have read that the largest volcanic eruptions may put enough sulphur dioxide into the atmosphere to "use up" all the water in the stratosphere. Since sulpur dioxide is a gas, so it won't settle out of the stratosphere like aerosols. As water mixes back into the stratosphere the sulphur dioxide could be reacted away over decades. I don't think anyone has really looked into this idea though. However, that is still not long enough to trigger an ice age in the sense of glaciers covering North America. Below link says a global drop of 3-5 celcius which seems like a reasonable estimate although I wouldn't be surprised if it could end up a bit larger. Tambora, and Pinatubo released signficant amounts of sulphur dioxide effecting climate but again not significant amounts of greenhouse gases.

http://news.bbc.co.uk/1/hi/sci/tech/628515.stm