Volcanos: Can They Alter Earth's Climate?

During several of the summer months of the year 1783, when the effects of the sun's rays to heat the earth in these northen climates should have been the greatest, there existed a constant fog over all Europe and parts of North America. This fog was of a permanent nature; dry, and the rays of the sun seemed to have little effect toward dissipating it. Of course, their summer effect in heating the earth was exceedingly diminished.
Hence, the surface was early frozen.
Hence, first snows remained on it unmelted.
Hence, the winter of 1783-1784 was more severe than any that happened for many years.
The cause of this universal fog is not yet ascertained. Whether it was adventitious to this earth, or whether it was the vast quantity of smoke, long continuing to issue during the summer from Hecla, in Iceland, and that other volcano which arose out of the sea near the island, which smoke might be spread by various winds over the northen part of the world, is yet uncertain.

--- Benjamin Franklin (1784)

I will be providing information on how volcanos affect regional and global climatic conditions.

As you can see below in this image of an erupting volcano in the tiny island of Montserrat, volcanos generate massive amounts of atmospheric particles. The eruption in Montserrat, which lasted nearly two weeks, produced this spectacular 40,000 foot ashcloud from the Soufriere Hills Volcano.

Document Curator: Tina Hansen (achansen@mtu.edu)