Question: How much pollution do volcanoes produce?

James Pope answered on 29 Jun 2012:

Hi tanyaxxx,

Volcanoes produce different types of pollutionand different volcanoes produce different polutants. I don’t know the specifics for a number of volcanoes, but I studied for my undergraduate research project the 1783 eruption of the Laki volcano in Iceland. It released 120 Mega-tonnes of sulphur dioxide into the atmosphere, which mixed with water to form an acid called Hydrogen Sulphate, which travelled on the winds to Europe, where it was deposited and caused a summer which was hazy everyday. This volcano caused crops to fail, the climate of Europe to cool for a summer and a winter, with temperatures reduced in some areas by 3°C in the winter of 1783/84 and for tens of thousands of people to die due to these issues.

On Iceland, a different chemical, Fluorine (a form of which is in some UK water supplies to help reduce teeth decay), was in high enough concentrations on the grass to kill 50% of the cattle on Iceland, and to cause 10,000 people to die, on an island which had a population of 40,000 at the time, so 1 in 4 people on Iceland.

Other volcanoes emit carbon dioxide, or create large ash clouds and these can have impacts on our climate, such as the 1815 Tambora eruption in Indonesia, which led to the “year without a summer” in Europe, because it was big enough to cool the climate thousands of miles away. Likewise the 1993 Mt Pinatubo eruption in teh Phillipines cooled average global temperatures by 0.2°C for a year to 18 months, which may seem small, but we presently cause 0.2°C of warming every 8 years, so a big impact from one volcano.