Cosigüina

After the large 1835 eruption of Cosigüina there was a dramatic global temperature decrease, lasting about 2 years. Had the eruption been extremely large and had  the sulfur (S) content been high, this cooling would be expected. However, the eruption may not  fit within these parameters.  It clearly was not a huge eruption.  It may have been sulfur rich but evidence for that is speculative. The evidence consists of one lava sample that has pyrite, which is not otherwise found in young Central American lavas.  It would be worthwhile to find glass inclusions inside minerals in the 1835 tephra.  If these trapped drops of magma are very rich in S then the climate deterioration at this time would have a plausible cause.

Sulfuric acid droplets are the major cause of "dust" introduced into the atmosphere by large volcanic eruptions.   Tambora, 1815, and Pinatubo, 1992, are examples of climate modifying eruptions whose Sulfur rich eruption clouds persisted in the stratosphere for about two years.

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