Icelandic Volcano Blows Again

From the Guardian:

Tens of thousands of passengers across Britain and Europe were grounded today as airports closed or faced severe disruption from a plume of ash caused by a volcanic eruption in Iceland.

All non-emergency flights in the UK will be grounded from noon to six because the after-effects of the eruption have made flying too hazardous, air safety officials said.

All flights in and out of Scotland were stopped earlier today with other airports facing severe disruption until the blanket ban was announced. Denmark's air space will close later this afternoon. Airports and airlines warned cancellations and delays were likely tomorrow and possibly longer as the ash continued to move south and east into northern Europe.

Flights are suspended all across Northern Europe from Finland to Iceland.

The Guardian has a useful live blog:

"No one can remember a time before when controlled airspace has been closed in the UK.
"This is certainly one of the most significant instances of flight restrictions in living memory.

 There's a nice map of the plume here:

The eruption is the same volcano, Eyjafjallajokull, that erupted last month, but yesterday's eruption was ten times more powerful and occurred under the glacier, melting a significant fraction of it.

One thing I haven't managed to get a handle on yet is how this eruption compares to the general scale of volcanic eruptions around the world, in terms of the plume.  I read last month in Hansen et al, "it is nearly certain that a new record 12-month global temperature will be set in 2010".  With plumes of ash going up to 55,000 feet, well into the stratosphere, and not slowing down at all after 24 hours, I'm wondering if there's a bit more uncertainty about that prediction now - though obviously it depends critically on how much material the volcano eventually pumps up there.

If anyone digs up any good quantitative comparisons, let me know - so far I haven't found anything.