Question: what will happen if all the volcanos erupted?

Philippa Demonte answered on 18 Jun 2011:

@selina97 Planet Earth may have looked like one giant volcano over 3 billion years ago, but it’s cooling down, so no more than around 20 volcanoes are erupting at any one time.

…..but theoretically what would happen? Global cooling, no planes allowed to fly, volcanic ash killing off crops, starvation…