Everyone needs friends like the two who told me the tsunami flattened nearby San Francisco. I replied “Are you trying to make me cry?”
I arrived at my motel in the Pacific NW yesterday after a day's drive, and the clerk started excitedly babbling about a volcano erupting. For a moment I thought he meant locally, like Shasta or Lassen or something had gone off. Freaked me out until I realized he was talking about Tonga.
It may affect global warming; I doubt it will be much however. It is all tectonics and part of the Pacific's Ring of Fire. Maybe if Yellowstone blew up global warming would be stopped.
Just depends on how many cubic km of ejecta there was.
I suspect it may be due to a hot spot similar to what caused the Hawaiian islands, rather than a tectonic spreading or subduction. Numerous chains of hot spots can be seen in the South Pacific if you look at a map of undersea stratigraphy. Or not. See section 3 on Island Origins
If Jellystone blows up about ten million people will no longer care.