Friday, October 28, 2011

Katla, volcanic ash, and other opinions on the effect of climate,

There has been an interesting set of quotations over on Dr. Curry’s Website which led back, through a post by Roger Pielke Snr to an article by Paul Voosen abouhow the changing aerosol and particulates in the atmosphere could be helping to control climate. While not wishing to get into that debate at the moment, (though the quotes are interesting, and should be read in context) one of the “complaints” of the scientists has been that there has not been a major volcano, with a significant impact on climate since Mount Pinatubo erupted in 1991. In that case, the second largest eruption of the 20th Century, ejected some 20 million tons of fine ash and sulphur dioxide into the upper atmosphere reducing global temperatures by about 1 deg F, for a couple of years.

In the current article one of the scientists at the Mona Loa observatory (John Barnes) has been monitoring the particulate content of the stratosphere and has noted that the count is going up, without such a major eruption. And it is that fact, discovered four years ago, that then leads into a discussion as to why the world isn’'t heating as fast as has been predicted. (In which discussion no-one brings up the new BEST study and the fourth figure in the Urban Heat Island paper which shows that large sections of the United States have had a negative, rather than a positive trend over the period of study. (Not that readers of the state temperature data given in posts listed on the lower right column will find that a new discovery – see for example, the discussion on the temperatures of the “Flat Middle”.

Which is, in itself, a good lead in to noting that Katla just earned another two stars (signifying earthquakes greater than 3.0 – with one being in the crater and one to the North-West towards the area of intense activity earlier this summer.

Earthquakes at Katla in the last 24 hours (Icelandic Met Office )

It is not that this necessarily brings this eruption much closer, though the smaller quakes are clustering again and Jon commented that there does not appear, as yet to be much harmonic activity (signifying significant magma movement ) yet, though there may be a small dyke intrusion into the caldera.

The question at the moment, I suppose is as to whether it will be the clustering that can be seen here under the right-hand star (the +3 quakes) that will intensify prior to the quake, or whether we will not get a major eruption until that cluster spreads to cover a broader region around the caldera. There are arguments on both sides.

But this may be the future source of some of those particles that John Barnes continues to seek, if the eruption lives up to some of its previous history. At the moment all we can do is wait and see whether the eruption comes this year, or not, and if it does how it will answer the question.

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