The Volcano Card
(Originally written April 19; posted May 12)
The unpronounceable Icelandic volcano (”Eyjafjallajokull”) that recently disrupted air travellers — including my then-Dubai-bound brother — is small enough that it probably won’t have a cooling impact on the global climate, like other volcanoes.
As such, 2010 remains on-track to exceed 1998 as the hottest year on record based on satellite measurements, as per these charts. 1998 was particularly hot on account of that year having a strong El Nino (2010 in contrast has a moderate El Nino).
The thing is, surface measurements don’t factor in heat retention, which is substantial for the world’s oceans! (It takes a lot of heat to melt ice, though the resulting water may still be at 0 degrees Celsius.)
The images above both come from this ClimateProgress post here.
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Which brings us back to Mt. Unpronounceable. Volcanic eruptions were pretty much the only phenomenon which could have prevented this year from setting a global temperature record, and cause the “cooling-since-1998″ crowd to flippantly switch to a “cooling-since-2010″ slogan. And now a volcano has popped up. How convenient… 
As noted earlier, this eruption would have to get a whole lot bigger before it starts registering an impact on the climate: to maim a line from The Simpsons, right now it’s no Chernobyl; it’s a mere Three Mile Island.
The reason volcanoes can have a temporary cooling effect on the atmosphere is that they throw up astounding amounts of sulphur compounds, which reflect incoming heat away from the surface of the earth. As those molecules fall out of the atmosphere (as acid rain, among other things) the cooling effect dissipates. Thus we have graphs like the following, taken from the site Skeptical Science, here:
You can see the cooling impact of volcanoes in the grey line. The negative radiative forcing from volcanoes Krakatoa (1883), Pelee (1902), St. Helens (1980) and Pinatubo (1991) are clearly visible. Not sure which volcano was the one in the 1960’s — maybe that was the eruption of the Beatles onto the British music scene.
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The cooling effect of sulphur aerosols has led some businessmen to suggest playing the “volcano card” — namely, releasing tonnes of toxic sulphur gases into the upper atmosphere every year, for centuries, to counteract the warming effect of accumulating greenhouse gases. Which is a Rube Goldberg approach to global warming if ever there was one. And which doesn’t impact the acidification of the oceans.
Predictably, these lot then suggest pouring millions of tonnes of alkaline chemicals into the world’s waterways to counteract oceanic acidification. Admittedly, to that point, I suppose we do have a lot of experience dumping chemicals into the oceans… 