Weather also conspired against Europe. Just as the volcano was erupting, the North Atlantic jet stream was passing over Iceland from the northwest, carrying myriad sharp-edged particles on a collision course with Europe's air fleets. "It's as if it's jinxed," says Helmut Malewski, who is tracking the ash cloud at Germany's National Meteorological Service's central forecasting office. "The wind blew from the east all winter. But just now, when the volcano goes active, it blows from the northwest." Dryness was another factor. "One strong rainstorm over the North Sea would have washed out the ash and helped us dramatically," Malewski says.But things may very well get a lot worse:
Still, things could have been a lot worse. In the past, volcanoes have disrupted the Earth's climate again and again. After the eruption of Mount Pinatubo in the Philippines in 1991, average global temperatures cooled by half a degree Celsius. Volcanoes are also the suspected culprits behind the mini ice age that occurred during the 17th and 18th centuries.
Despite its might, Eyjafjallajökull hasn't forced its plume high enough for that to happen. Ash from the volcano's plume has reached an altitude of only about 10 kilometers (six miles), not high enough to reach the stratosphere. "So the gas and particles will remain below that in the troposphere and will be carried down to the Earth's surface by rain in the coming days or weeks," says Michael Bittner of the German Aerospace Center (DLR) in Oberpfaffenhofen.
The volcano has also blown less toxic ash and gasses into the air than many of its cousins. Bittner and his team have reviewed images taken by the Eumetsat satellite and concluded that Iceland's Eyjafjallajökull has spewed 2,000 tons of sulphur dioxide into the air. Pinatubo spouted 10,000 times that amount. "Even if it remains active for an extended period of time, it still won't come anywhere close to the scale of Pinatubo," Bitter predicted.
But all that could change if Eyjafjallajökull awakens its larger brothers. The Katla volcano, barely 25 kilometers to the east, has enormously higher explosive power. It also has a rather nasty habit of erupting shortly after Eyjafjallajökull. The last major eruption of Eyjafjallajökull lasted for two years, ending in 1823 when Katla erupted like a massive cannon.
So far, Katla hasn't reacted -- GPS stations haven't registered any movements in its slopes. But there's still another fire-spewing giant in the area -- Heckla. "That volcano erupts, with a regularity that astonishes geologists, every 10 years," says Thomas Walter of the German Research Center for Geosciences (GFZ) in Potsdam. "It is long overdue."
Such chain reactions are not uncommon for volcanic mountain ranges, especially in Iceland. "If one volcano erupts next to a neighboring one where pressure has also built up, then it can give it the decisive kick," says Walter. But he won't venture to predict when the next volcano will erupt.