What are the effects that a large-scale volcanic eruption can have on the global climate?

1 Answer
Feb 15, 2017

Depends on the size of the eruption and location.

Explanation:

The largest eruption humans have witnessed (Mt. Tambora 1815) was followed by "the year without summer" due to all the ash in the atmosphere blocking sunlight. When Krakatoa erupted in 1883 it resulted in a 2-3 degrees global temperature drop for about 5 years.

For volcanoes closer to the poles the result is a bit hard to predict. The big eruption in Alaska in the early part of the 20th century cooled temperatures in the arctic, but the chain reaction to that ended up giving India a hotter and drier summer than normal.

What is particularly alarming is that even though volcanic ash is much, much worse than carbon dioxide, humans release 3-4 times as much carbon dioxide (by mass) per year than these massive volcanic eruptions.