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Could increased volcanic activity mean an early fall frost?

An article in AgWeb newsletter on June 11 discussed the possibility of an early frost this year due to increased volcanic activity this year compared to previous years.  This long-range forecast was made by Simon Atkins, CEO of Advanced Forecasting Corporation.  You can read the article by clicking here.  Does volcanic activity lead to early frosts?  In fact, it could.

Volcanic eruptions put out ash which can block the sun from reaching the ground.  More importantly, they also put out sulfuric acid, which forms tiny drops that fly high into the atmosphere and act like tiny reflective beads (similar to the glass beads they use on reflective street signs) which reflect sunlight back to space before it can reach the earth’s surface and warm it up.  After big volcanic eruptions, temperatures across the globe can be cooled for several years.  The last major eruption was Mount Pinatubo in 1991 but other eruptions have had similar effects, including Mount Agung in 1962 and Krakatoa in 1883.  One of the biggest eruptions of all was Mt. Tambora in 1815, and led to the “Year without a Summer.”

In the last few years, volcanic activity has decreased and volcanic aerosols have not been a big factor in climate.  But the number of smaller eruptions has increased this year, and even though each one puts less sulfuric acid into the air than one big eruption, the total amount of sunlight reflected could cool off the earth this year.  This could make it easier for temperatures to fall to 32 F in the fall, potentially leading to an earlier frost.  But there are a lot of uncertainties in the frequency of cold outbreaks, moisture levels and the potential impacts of the developing  El Nino which could also affect fall temperatures, so an early frost is far from certain.