Overnight, the closely watched Bárðarbunga volcano in Iceland officially went from rumbling to erupting under the ice. The Icelandic Met Office has already issued a red alert for planes, but it's unlikely to turn into a repeat of the flight cancellation shitshow of 2010 -- thanks to better science about volcanic ash.
Whether a volcano will erupt quietly or shut down down all of Europe's aviation depends on a combination of three factors: How much ash the volcano spews out, what direction the wind is blowing, and, finally, how much we know about the location and amount of volcanic ash, which can clog up jet engines. The first two are pretty much unpredictable, though the situation with Bárðarbunga is looking ok so far.
Rules and atmospheric models of volcanic ash, however, have changed quite a bit since Eyjafjallajökull caught us off totally guard in 2010. A year later in 2011, Iceland actually had its biggest volcanic eruption in 50 years. But does anyone remember (the marginally more pronounceable) Grímsvötn, which spewed out twice as much material in 1/10th of the time? Probably not, because it caused less than 1 per cent as many cancelled flights as Eyjafjallajökull.
How do those numbers add up? Part of the reason Grímsvötn was less disruptive was the wind didn't blow directly into Europe. But different volcanic ash rules were also at play. Prior to Eyjafjallajökull, planes could not fly when there was any volcanic ash in the sky. After more than week of airport closures in 2011, aviation officials relaxed the rules so that planes could fly in up to 4000 micrograms of ash per cubic meter of atmosphere. Those rules have been in effect ever since.
Another factor is modelling. The UK Met office has better models for how a plume of volcanic ash travels through the sky. Better atmospheric models means less uncertainty, so we don't have to close off airspace out of extra caution. Airlines are also testing sensors on planes to detect ash even more accurately.
Eyjafjallajökull was a real wake-up call to the aviation industry, and now the European Organisation for the Safety of Air Navigation, or EUROCONTROL, does yearly volcanic ash crisis exercises to prepare air traffic controllers for potential volcano chaos.
So we're definitely better prepared for volcanic ash than in 2011. Of course, how this plays out still depends on how the volcano and the wind behave. Bárðarbunga is only erupting under ice so far, and no airports have been affected. If that changes, we'll be sure to let you know.
Top image: Bárðarbunga looking calm for now. Iceland Met Office