19 April 2010

Some reflections on the Eyjafjallajoekull ash cloud

Posted by Dave Petley

Over the weekend I have been watching and reading the media response to the aviation ban resulting from the Eyjafjallajoekull ash cloud, and reading some of the online discussions.  I would like to make four observations from a natural hazards perspective:

A. This event is the result of a “perfect storm”.
I have been surprised by the lack of reflection by the media, including by some scientists (see below), that the current event really is the result of an extraordinary set of circumstances.  To generate the current crisis, three events had to occur simultaneously.

  1. The volcano had to suffer an eruption that puts large amounts of ash high into the atmosphere.  Many eruptions do not do this, which is why we rarely see these types of crises even though eruptions occur regularly around the world.  In fact this volcano has been erupting for a month, but the initial events did not inject ash into the high atmosphere. 
  2. The jetstream needed to be located over Iceland.  If the jetstream had been to the south then the ash would not have been brought to Europe.  
  3. The atmospheric conditions over Europe had to be extraordinarily stable.  Those of us who live here know that what we are seeing in northern Europe is not typical (though it is not all that rare either).  Usually we see a conveyor belt of low pressure systems from the southwest.  At the moment we have stable high pressure and no wind, which means the ash is lingering.

If any of these three conditions had been different then this event would not have occurred.  It is the rare (and quite unlikely) confluence of these three conditions that have led to where we are.

2. Some pronouncements by scientists really have not helped. 
The media are now in a pickle as they have to keep the story on the front page, but finding new angles is a challenge.  For this reason, alarming pronouncements by scientists are a goldmine.  A number of prominent scientists (no names) have been warning that the eruption could go on for months, or even years, and that Hekla might cause an even bigger eruption.  For goodness sake, please stop!  There are no indications that Hekla is about to erupt; the linkage between Eyjafjallajoekull and Katla are not clear; if it did erupt, a similar problem is not inevitable if the jetstream or the European weather conditions are different; and it is not helping to raise concerns about another eruption.  In a similar manner, suggesting that the volcano might cause us problems for months or years is not helping either.  Yes, an eruption may continue, but the chances that it will continue to inject ash into the high atmosphere are not high, and most of the time the ash wouldn’t be brought over Europe.

Unfortunately, doom-laden predictions undermine the credibility of science and scientists when the situation calms down, as it inevitably will.  This is not helpful.

3. Environmental science / natural hazards research is grossly underfunded
The third lesson is that these events can have a big impact on our lives and our economy, but our investment in research into them is pitiful.  The limited capability that we have in Europe to collect good samples from the upper atmosphere is all to obvious, for example.  A comparatively small investment in the science would reap large rewards at a time like this, and would provide financial benefits many times greater than the costs.  If there is one thing that should come out of this it is a recognition that we have to invest in hazards research.

4. The general understanding of risk is very poor
It has been extraordinary to see pronouncements that the successful operation of the test flights over the weekend means that the flight ban is an over-reaction.  The fact that a small number of flights can successfully operate does not mean that the skies are safe.  It may be that the safety of, say, only 1 flight in 10,000 is put at risk by the ash, caused by very isolated pockets od denser / more abrasive material.  As there are 28,000 flights per day in Europe, this would not be an acceptable risk.  Unfortunately, due to the lack of research we do not know what true probabilities, but the Finnish F-18 engines suggest that they are far from trivial.