Mod 6.2 - Impact of Natural Disasters on the Biosphere (Eruptions, Biosphere and Atmosphere) Flashcards
How does a major volcanic eruption cause global cooling?
In a major volcanic eruption with VEI greater than or equal to 5, erupted sulfur dioxide and water vapour tend to react to form a solution of sulfuric acid, which freeze in the upper troposphere or lower stratosphere and produce a sulfur aerosol that is highly reflective of incoming solar radiation. This can cause medium to long term global cooling.
Volcanic ash or dust released into the atmosphere during an eruption can remain in the sky for a long period of time, reflecting incoming solar radiation and thus causing temporary cooling. Larger particles of ash have little effect because they fall out of the air quickly. Small ash particles can form a dark cloud in the troposphere that shades and cools the area directly below. This may remain from a few minutes to a few days.
Example - In 1815, the Mount Tambora eruption in Indonesia produced a marked global cooling that led to an approximate 0.6 degree hemispheric drop in temperature for a decade.
How does a major volcanic eruption cause global warming?
A volcanic eruption releases potent greenhouse gases such as water vapour, carbon dioxide and carbon monoxide.
