That Eyjafjallajokull volcano in Iceland may be creating havoc with air travel, but so far it doesn't appear to be posing any threat to weather and climate.
In 1991, the spectacular eruption of Mount Pinatubo in the Phillipines spewed so much ash into the upper atmosphere that the volcanic veil resulted in a worldwide cooling.
So far, said Rutgers University volcano expert Alan Robock, not much in the way of sulfur dioxide has been ejected into the atmosphere by the Icelandic volcano, which blew for a second time yesterday.
However, if the volcano does manage to emit more sulfur dioxide, it could ultimately have an impact.
He noted that the 19th Century Laki eruption in Iceland lasted eight months and had a significant effect on climate.
He added that a similar eruption today could shut down European air travel for six months or more.