April 15, 2010

Iceland's Volcanic Eruption: Will it influence weather and climate?

Dust Plume from Mount Eyjafjallokull seen by a NASA MODIS satellite

There have been a number of inquiries about the impact of the eruption of Iceland's Mount Eyjafjallokull volcano (how do you pronounce it?&%). I have a lot of interest in the weather/climate effects of volcanoes and have written several papers on it, including a paper on the local weather effects of Mount St. Helens.

The volcano has sent a plume of ash, dust, and gases to altitudes of 40-50 thousand feet, high enough to be spread rapidly east by the jet stream winds aloft. The immediate danger is to aviation: the dust can clog jet engines, with the silica component melting and hardening on jet turbine parts.
But what about weather and climate?

This was not a particularly explosive event--not the equivalent of Mt. Pinatubo or St. Helens, to name only a few. The big question is how long the volcano will continue to erupt--the last major event of this volcano in the 19th century lasted a few years, but at a relatively low level. I have included some satellite images of the dust plume. In the picture at the top of the blog you can clearly see the dust (brown color) extending southeastward from Iceland. Another image is found below.

Using satellite observations and knowing the winds aloft, we can track and predict where volcanic dust clouds will move. Here is the recent distribution at several times of the current event.

The weather effects will be modest and short-lived. The large dust particles fall out or are washed out of the atmosphere, so if the eruption stops the dust will be removed in a matter of days. Weather effects include a loss of solar radiation and thus cooling during the day, while at night the dust plume can act to reduce the loss of infrared radiation to space and thus warm. Significant weather effects will be limited to Iceland and immediately downstream for a hundred miles or so. St. Helen's plume caused 10-15F cooling during the next day over eastern Washington. 48h later, the effects were hard to notice.

But what about climate changes? Dust and ash fall out quickly and have no climate impacts. But the sulfur dioxide gas can be lofted high into the stratosphere and combine with water to form sulphuric acid and sulfate particles that can produce a haze that stays in the stratosphere for several years (typically 1-3 years). Such hazes scatter some of the sun's rays back to space and produce cooling. In fact, several studies have shown a major eruption (in terms of injecting sulfur dioxide into the stratosphere) can cool the planet down by several degrees centigrade. Perhaps the most famous example is the "Year Without a Summer" of 1816, following the great eruption of Mt. Tambora in 1815. Killer frosts hit the NE U.S. and Europe in June 1816, crops failed, and amazing sunsets reigned.

So the big question is how sulfur rich is the Iceland eruption, how much is getting into the stratosphere, and how long will the eruption last. A major eruption could tame global warming for a few years and in fact some geoengineering advocates think we should deliberately spread some kind of dust particle in the stratosphere to mimic an endless volcanic eruption. But this has a downside....such particles contribute to the destruction of the ozone layer. From initial reports, the sulfur content of the Iceland eruption is relatively low, so that would lessen its climate impacts. Another factor is the latitude of the eruption. Low-latitude eruptions have the most climatic impact since sulfur dioxide gas and resulting aerosols can spread northward into both hemisphere in the stratosphere, while midlatitude and high latitude eruptions tend to stay over northern latitudes, thus influencing a far smaller portion of the globe. Iceland is obviously pretty far north.

And one more local factoid: Mt. St. Helens injected lots of dust and ash into the atmosphere, but was relatively sulfur poor--thus, it had virtually no climatic impact.


  1. Could this have been the source of the "dirty rain" that covered my car on Kent's East Hill on Monday (4/12) morning? It looked just like a dusty car that had been rained on, but closer examination leads me to believe the rain contained the dirt. My wifes (clean, garaged) car also got dirty in a Monday afternoon shower.

  2. Mount Eyjafjallokull volcano (how do you pronounce it?&%)

    The correct spelling is Eyjafjallajökull and according to the Seattle Times it is pronounced ay-yah-FYAH'-plah-yer-kuh-duhl!

    Wikipedia also has an audio file for the volcano's name here: http://upload.wikimedia.org/wikipedia/commons/1/10/Eyjafjallaj%C3%B6kull.ogg

    What a mouthful!

  3. It is a shame what is going on with air traffic, but I do look forward to the aerosol-influenced sunsets like those provided by Sarychev's eruption last year..

  4. Loved your comment on KUOW this morning about non-expert TV weather personalities lecturing the public on climate change (or the absence thereof)... thank you for reminding us all to question so-called expert statements from politically motivated public figures.

  5. Kurt, based on a number of observations at our house in East Bellevue over the past few days, I would suggest that the "dirty rain" on your car was caused by tree pollen, not volcanic ash. Since I have no plans to fly anywhere soon, I WISH it was volcano dust instead of pollen! Achoo!

  6. As I understand it from the article linked below, it is not Eyjafjallajökull volcano that is the danger to climate, but the one near it that has historically always erupted after this one. We will have to see if that pattern repeats this time.


    If you want to keep a watch on the eruption here are some links:





  7. Here is a link to air quality networks for particulate matter in London. To date there is no apparent detection of any fallout.
    Not really sure why the massive air space shutdown other than EXTREME caution. Still the plume is pretty well defined and it would seem air traffic could be vectored away or around not unlike other hazardous weather.
    Different note: The name is some scrabble word. Sort of like an old girlfriend I had in Hawaii-


Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

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