Saturday, April 17, 2010

The Eyjafjallajökull Volcano, Air Travel, and Arctic Ice

The eruption of the Eyjafjallajökull volcano in Iceland is spreading ash across much of northern Europe, and worse problems could occur. The volcano is located in the middle of the fourth largest glacier in Iceland (also called Eyjafjallajökull), and the first fear in connection with the volcano was that it would melt the glacier and cause flooding. Several hundred people were evacuated from the potential flood plain, and waters quickly rose high enough to close the main highway through the affected river delta.

A greater concern with the glacier, however, is that volcanic gases trapped under the ice are being released in explosions that also send huge amounts of volcanic grit and sand into the air. This is the most hazardous component of the volcanic ash for airplanes. As I’ve heard it described, flying an airplane through the volcanic ash would be like pouring sand into the engine. The unusual abrasion carries a high risk of equipment failure, the kind that could lead an airplane to crash. It is better if airplanes just don’t go near the cloud of ash.

This explains why the volcanic eruption led to a total ban on air travel in the United Kingdom for the first time since the invention of the aircraft, and only a few countries in the far corner of Europe have escaped the cascade of flight cancellations. Travelers stranded on both sides of the Atlantic may have a long wait. I am told that the last time Eyjafjallajökull erupted, it lasted for three years. If the situation does not change soon, travelers in London may have to take a train to Rome or a ferry to Lisbon to catch a flight to North America.

It would be better for air travelers if the wind were blowing in the opposite direction, but this would create a very different kind of problem. With winds over Iceland blowing away from Western Europe, the volcanic ash would be settle out over the Arctic Ocean north of Greenland and Canada. The ocean is covered with ice at this point, and a layer of very bright, reflective snow on top of most of the ice protects it from the sunlight that, at this time of year, would otherwise melt it. Volcanic ash is not terribly dark, but it is much darker than snow, and it could triple the rate of the top-down component of the ice melt. The result could easily be a near-total melt of all the ice in the Arctic Ocean for the first time in recorded history.

The loss of Arctic sea ice would be more than just a curiosity. It would allow the ocean waters to absorb sunlight in a way they never have before, permanently warming the Arctic Ocean and accelerating the ice loss that is occurring already. A warmer Arctic would eventually turn into a noticeable amount of warming worldwide, and it would create warmer and more volatile weather across most of North America. Warmer weather and storms would speed the melting of the Greenland ice sheet, leading to rising sea levels. These are effects that were already being seen, even without a volcanic eruption. If the Eyjafjallajökull eruption continues through the spring and summer — and no one knows whether this will happen or not — the winds eventually will have to change direction and send some of the volcanic ash onto the Arctic ice.

There is no direction that the winds could blow to disperse such a large amount of volcanic ash harmlessly. Iceland sits between Europe, North America, and the Arctic, and the wind from Iceland almost has to blow toward one of those targets on any given day. Volcanoes have had huge effects on the last 80,000 years of human history, and while it’s more likely that the impact of the current eruption will occur on a smaller scale, the truth is, we have no way to predict that.