Volcanoes and Weather
Meteorologists and volcanologists have now for a while
that volcanoes have a major affect on weather. Not only
are they a major contributor to acid rain but can in some
cases change climates.
Sometimes volcanoes on destructive plate boundaries throw up huge quantities
of volcanic ash. This ash can be propelled into the stratosphere where it may
remain for years. Volcanic ash absorbs radiation from the sun which causes
cooling to the earth below. Eruptions in high latitudes affect only one
hemisphere where as equatorial volcanoes like Krakatoa may cause global cooling.
In the last 100000 years there have been some awesome explosions of
volcanoes, dwarfing any modern eruption. The largest eruption took place 75000
years ago which must have blasted dust to over 55 kilometres high! It created a
dust veil over the earth which many scientists believe caused an ice age.
All very exciting but wasn't this all a long time a go - well yes and no.
There have been no eruptions like that for a while but smaller eruptions which
have happened which have changed world climates temporarily. For example in 1815
an eruption of Tambora in Indonesia caused 'a year without summer' which
inspired Byron to write his famous poem 'Darkness.'
In fact climate changing eruptions occur every 150-200 years. Perhaps the
most significant eruption took place at Krakatoa, Indonesia in the 13th century.
The eruptions cause a climate change and it is now the popular view that this
triggered the start of the 'Black Death' which wiped out half the population of
There are other examples of drought, acid rain, cooler climate, storms etc;
the risk from volcanoes has not gone away. A mega-explosion could cause a world
wide drought or even cause another ice age...
Volcanoes are rarely mentioned in relation to climate change mainly because
environmentalists are obsessed with man made causes (which are a problem).
However, I fear volcanoes more than global warming and I think more needs to be
done to understand them.