By: Jeff Johnson, Telvent DTN Chief Science Officer and Certified Consulting Meteorologist

Recent eruptions of the Eyjafjallajokull Volcano in Iceland have greatly impacted air travel and commerce across Europe. While volcanic eruptions are common around the world each year, this particular one is having such a large impact due to its location just to the northwest of mainland Europe. Prevailing winds have been carrying ash from Iceland toward Scandinavia where the winds have then turned to the south into central Europe. Lower level winds then curve back toward the west which has sent the ash particles toward France and the eastern Atlantic.

The initial eruptions of this volcano are estimated to rank between 2-3 on the Volcanic Explosivity Index (VEI). This scale ranges from 0-8 and is similar to the earthquake scales where for every increase in index value, the intensity is ten times greater. For comparison Mt. St. Helens in 1980 ranked near a 5, while the large 1991 eruption of Mt. Pinatubo in the Philippines ranked a 6. The last VEI 8 eruption occurred 73,000 years ago in Indonesia. Climate impacts would normally require an index value of 5 or greater for any long-lasting global influences. The eruption of the Icelandic volcano so far has been on the weaker end of the spectrum, with the ash cloud remaining in the lower half of the troposphere. The highest the ash column has risen has been between 15,000-25,000 feet.

If the eruptions of this volcano ended now, there would be little impact upon the global climate. With the ash cloud only in the lower portion of the atmosphere it is likely that the particles will settle out or be "rained out" of the air in a few days or weeks. If there are further eruptions that can send the ash cloud above 30,000 to 40,000 feet, then the particles have a better chance of lingering in the high atmosphere for weeks and months to come. This remains a possibility since the last time this particular volcano erupted in 1821, the eruptions continued intermittently for over a year. Should this happen, the climatic impact that would most likely be felt would be slightly cooler temperatures over the northeastern third of the U.S. as the negative arctic oscillation pattern would gain strength. But for now, the eruptions are not significant enough from a climate change perspective.