An eyeful of Eyjafjallajökull: no cooling threat (yet)


NASA’s Terra satellite captured this spectacular image of a plume of volcanic dust from the ongoing eruption of the Eyjafjallajökull volcano in Iceland. It’s blowing south and east from Iceland (top left) towards Scotland and Norway, and has caused the cancellation of most aircraft movement over Western Europe, with knock-on disruption around the world. New Scientist explains why here. It’s well known that large volcanic eruptions can cause the earth to cool, as they can push large amounts of sulphur aerosols into the stratosphere, reflecting away incoming solar radiation. The eruption of Mt Pinatubo in 1991 is the most recent example. It caused a global cooling of about 0.5ºC over the 18 months following the eruption. Artificially creating the same effect by injecting sulphur into the stratosphere has been suggested as one possible method of geoengineering a response to global warming.

Could the current eruption cause significant global or regional cooling? That question is already being asked, but the answer seems to be no — at least for the time being. Jeff Masters has a good post discussing the issue, and points out that volcanic eruptions in the tropics have the biggest effect because the atmospheric circulation tends to rise and spread dust and aerosols both south and north of the equator around the whole planet. At mid or high latitudes, the circulation tends to be moving polewards and sinking, and this limits the effects to one hemisphere. However, truly massive eruptions, such as that of Eyjafjallajökull’s neighbour Laki in 1783-4, can cause dramatic regional effects. There are good descriptions of the disruptions to European and North American weather at the time at the Wikipedia page: it quotes British naturalist Gilbert White’s journal for summer 1783:

The sun, at noon, looked as blank as a clouded moon, and shed a rust- coloured ferruginous light on the ground, and floors of rooms; but was particularly lurid and blood-coloured at rising and setting. All the time the heat was so intense that butchers’ meat could hardly be eaten on the day after it was killed; and the flies swarmed so in the lanes and hedges that they rendered the horses half frantic, and riding irksome. The country people began to look with a superstitious awe, at the red, louring aspect of the sun.

Eyjafjallajökull’s current eruption has not approached the scale of that 18th century event, but there are fears that it could trigger new eruptions in neighbouring volcanoes. A good place to monitor what’s going on is Dr Erik Klemetti’s Eruptions blog at Scienceblogs. If you want to know how to pronounce the name, try this, and this recent video of the eruption is well worth a look.

11 thoughts on “An eyeful of Eyjafjallajökull: no cooling threat (yet)”

  1. The real story here is that you can immediately halt all European flights, thus removing a massive source of GHGs, making a significant contribution to preventing runaway climate change, and there is social disruption, but no large scale loss of life, or food supply.

    But of course we currently prefer to take our non-essential flights today and let our grandchildren endure loss of life, food shortages etc etc.


    My recent post Travel industry imagines a world with far fewer flights

  2. Mind you because of the economic effect of stopping the flying we could allow it to continue and let those passengers in the planes (and their families etc) absorb the effects…

    1. Thanks Mauri. I downloaded a pdf called Radar observations at the Eyjafjallajöklull eruption site 14 Apríl 2010 (Institute of Earth Sciences and the Icelandic Coast Guard), and it shows three vents in the centre of the glacier. There have been some impressive jokulhaups as well — there are links at the Eruptions blog linked above. According to the latest post there, the eruption is showing no signs of slowing and winds are still blowing ash towards Europe.

    1. There's a suggestion that where an ice mass sits on top an active volcanic zone — as in parts of Iceland — that a reduction in that mass by long term melting could lead to greater amounts of magma generation in the crust. I think it's regarded as plausible, but not proven.

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