Thursday 22 February 2018

Sublime sunsets but no changes to weather expected

Allison Bray and Treacy Hogan

THE cloud of volcanic ash that brought Ireland's airports to a standstill yesterday has a silver lining for Irish photographers and painters who can expect spectacular sunsets starting tonight and well into next week.

But unlike the 1991 eruption of Mount Pinatubo in the Philippines, the eruption under the Eyjafjallajokull glacier in Iceland on Wednesday is not expected to cause any undue weather or climatic changes here, unless it continues to erupt.

Meteorologist and climate change expert Professor John Sweeney of NUI Maynooth said the gritty ash trapped in the cloud about 55,000 feet above sea level reflects on sunlight leading to extremely luminous and dazzling sunsets.

He said famous paintings with sunsets in the background, including Norwegian painter Edvard Munch's 1893 masterpiece 'The Scream', may have unwittingly captured the vibrant orange sunset over much of Northern Europe due to the eruption of Mount Krakatoa in Indonesia in August 1883.

The best sunsets will likely be seen off the west and northwest coast of Ireland for the next week or until the dust settles, he added.

While the Mount Pinatubo eruption led to a global temperature drop of about half a degree, resulting in wet and cool summers in 1992 and 1993 across much of the world, the circumstances are very different in the latest eruption.

Mount Pinatubo was located much closer to the Equator which led to a veil of dust blanketing much of the world.

But because the Icelandic volcano is located at a much higher altitude, the dust will gravitate closer to the poles which will limit any potential global impact, he said.

The ash is also located in the troposphere, or weather belt of the atmosphere, which means it will most likely be washed out by rain.

"It's not likely to produce a major climate effect," Prof Sweeney told the Irish Independent.

However, this could change if the volcano continues to erupt.

"Icelandic volcanoes can continue to erupt for years. If it continues to erupt for several years, it could contribute to global cooling which would also limit the warmth of the sun and contribute to haze that would result in more cloudy, cool and wet weather," Prof Sweeney added. "But it's too early to say what will happen," he said.

Even if it does lead to global cooling, it will still not cancel out the effect of global warming.

"The amount of carbon dioxide from volcanoes is minimal compared to what comes out of the 'human volcano'," Prof Sweeney said.

Met Eireann meteorologist Gerald Fleming last night said it's unlikely Ireland will experience any adverse weather or environmental effects from the volcano. The plume of ash was too high up in the atmosphere to fall to earth unless it's washed down by rain.

No rain is forecast here for the next few days, although strong northwesterly winds in the next few days may blow the plume over Ireland and the British Isles which would cause fresh aviation havoc.

The eruption in 1815 on the Indonesian island of Sumbawa caused freak weather conditions throughout the world.

Mount Tambora sent out huge volumes of sulphur dioxide which combined with water vapour to form a sulphuric acid mist that reflected sunlight away from the earth. That caused such a drop in temperatures that 1816 became known as "the year with no summer".

In Ireland, rain fell on 142 days that summer and across France the grape harvest was virtually non-existent.

In North America there was snow in June and lakes and rivers froze as far south as Pennsylvania in July and August.

Irish Independent

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