[Junior]

It would dump several hundred cubic kilometers of dust into the air, lowering the world's temperature several degrees. According to the Discovery Channel show, the ash fall was two meters deep 1200 kilometers from the caldera 600,000 years ago.

[RightWhale]

lowering the world's temperature several degrees

Seems like that would bring on an Ice Age if the blowout is big enough. We missed a summer up here when the Philippines volcano let loose. Lots of snow the next winter as well.