Volcanic eruption could adversely affect Irish weather

If Montserrat's quarrelsome volcano finally blows its top it could affect Ireland's weather, bringing more storms and stronger winds.

Volcanic eruptions are thought to have altered weather patterns in not too distant Edinburgh, according to a newly-published study, but more research would be needed to determine whether Ireland also suffers when volcanos decide to turn violent. Dr Alistair Dawson, an earth scientist at Coventry University in England, and Dr Kieran Hickey, of St Patrick's College, Maynooth, examined highly detailed meteorological records for the Scots capital stretching back over 200 years.

Their work is published in the current issue of New Scientist. They found that Edinburgh suffered the most gales in the winters that followed three of the biggest volcanic eruptions over that period. After two Indonesian eruptions in the 1800s and another in Mexico in 1982, Edinburgh was hit by gale-force winds for up to 70 days, twice its usual frequency.

Their work only considered Edinburgh because it has the oldest wind velocity records of any European capital. It is therefore not clear whether changes in weather patterns were also experienced in Dublin, London or Manchester.

The impact of volcanic eruptions on weather is a widely recognised phenomenon, however, according to Prof Chris Stillman, a volcanologist at Trinity College, Dublin.

"Certainly, the really great ones which released huge amounts of material into the upper atmosphere affected the weather," he said yesterday. "There is no doubt at all that each of the major eruptions caused weather disturbance."

The changes come about when hundreds of tonnes of material are blown upwards. Dust and ash that reaches the stratosphere more than six miles above the earth are picked up by the jet stream, high speed winds that circle the globe.

These distribute the material creating a "volcanic dust veil".

It causes several changes, Prof Stillman said. The atmosphere cools as more sunlight is reflected back by the dust particles and water vapour can also disturb the o-zone layers.

The changes can be very localised so while Edinburgh suffered gales, Dublin after these eruptions might have escaped with gentle breezes.