How can a volcano wipe out the world?

Answer 1

It does not seem at all likely that a volcano could wipe out the world, although a large eruption could cause damage for possibly hundreds of miles. However, it is not inconceivable that a volcano could wipe out the world. The gas that volcanoes emit can include carbon dioxide. A volcano might emit an excessive quantity of carbon dioxide, of which we already have too much in our atmosphere. This could lead to a catastrophic process of global warming.

_________________________________________________________________

Improvment: It won't happen but if a volcano of exceptional size were to erupt, the vibrations and spewing of lava will spread and pollute the air with gasses and ash. If the winds were stong, the gasses and ash would spread and suffocate all living things.