From: Allison Winter, ENN
Published June 10, 2013 03:06 PM

Volcanic Eruptions Linked to Cold Weather Events

When a volcano erupts, it's not just the local area and weather that will be affected. In fact, weather and climate around the world can be influenced, as large eruptions throw volcanic ash particles into the stratosphere.


Locally, these particles attract water droplets and therefore cause rain events. In addition, higher occurrences of thunder and lightening are observed in the area. But the release of sulphur dioxide gas into the stratosphere, which converts into sulphate aerosol particles, reflects incoming sunlight and creates an overall temporary cooling effect of a much larger area on Earth's surface.

To study these effects, researchers have analyzed medieval chronicles in order to catch a glimpse into how historical volcanic eruptions affected the weather in Ireland up to 1500 years ago.

The Irish Annals are a series of written entries detailing major historical and political events, as well as a systematic and sustained reporting of meteorological extremes.

Researchers assessed over 40,000 written entries in the Irish Annals and compared them with measurements taken from ice cores, successfully linking the climatic aftermath of volcanic eruptions to extreme cold weather events in Ireland over a 1200-year period from 431 to 1649.

48 volcanic events were noted and 38 were associated, closely in time, with 37 extreme cold events, which were identified by systematically examining written entries in the Irish Annals.

Lead author of the study, Dr Francis Ludlow, from the Harvard University Center for the Environment and Department of History, said: "It's clear that the scribes of the Irish Annals were diligent reporters of severe cold weather, most probably because of the negative impacts this had on society and the biosphere.

"Our major result is that explosive volcanic eruptions are strongly, and persistently, implicated in the occurrence of cold weather events over this long timescale in Ireland. In their severity, these events are quite rare for the country's mild maritime climate."

While the global effects of recent eruptions are quite well-known and understood, less is known about their effects on climate before the beginning of instrumental weather recording, or their effects on regional scales. However, the Irish Annals provided an opportunity to explore both of these issues.

"It is on the regional scale that we need to refine our understanding of this relationship as ultimately, it is on this scale that individuals and societies plan for extreme weather," continued Dr Ludlow.

The study was published last week in the journal Environmental Research Letters.

See more at the Institute of Physics.

Volcano image via Shutterstock.

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