Thursday, January 8, 2009

Arctic Volcanic Multiplier

Piecing together the effect of volcanic activity on the global climate, I recently recognized an oversight. It is that there must be an order of magnitude difference between the impact of an equatorial blast and an Alaskan blast. More importantly, while an equatorial blast has good prospects of affecting the whole globe, an Alaskan blast is going to be limited to the northern portion of the northern hemisphere. This rather obviously coincides with the details of the little ice age.

That also explains the savage impact on climate of the 1159bc Hekla blast that suppressed temperatures for a full generation throughout Northern Europe. It only had to be a much too normal one to three cubic mile event that kept cooking at a smaller scale for a few years to do its job as advertised.

This also makes explaining the Little Ice Age much simpler. Instead of two or three close together, we now need a major volcano that keeps cooking over fifty or more years in the Alaska Russian volcanic arc. Ash and aerosols need to feed into the Arctic weather gyre where escape is difficult and protracted over time. This will induce sharply lower temperatures that then impact Europe.

There is a very good chance that it is a single specific volcano. I say that because there is erratic evidence of a several century long cycle that could easily coincide with the active phase of one volcano. The good news is that we have three or four centuries of good weather before it is heard from again. The bad news is that there are plenty of other volcanoes thinking about it.

Mt Pinatubo in the Philippines impacted our climate for perhaps three years and reduced temperatures by a significant amount. Had it been in Alaska, its effect could well have been multiplied by an order of magnitude and have surely ravaged Europe.

We need to identify an aerosol rich volcano able to charge up the Arctic atmospheric gyre easily and perhaps monitor it if that is not already happening. The known suspects have not been that significant but that only means that the main event is apparently dormant.

This comfortably explains the episodes of radical cooling that have typically occurred in the Northern Hemisphere and cannot be explained as Global in origin or by the more benign Pacific Decadal Oscillation. A three or four degree drop caused by a volcano explains ice on the Rhine, or even the Nile. Fortunately these events are not particularly long lasting most of the time and recovery is pretty predictable. A farmer will have one year of crop failure to deal with before he adjusts to the tougher conditions with more robust crops and we learn to like oatmeal.

By the output been trapped in a small area of the globe, the volcano’s effect on climate is hugely magnified. It fortunately still disperses fairly quickly. The only reason that this is as yet not fully understood is that we have not had the chance to watch it unfold as we watched Mt St. Helens and Mt Pinatubo unfold. We are sure to get the chance.

And yes, let us warm up the earth with reforesting the Sahara. The climate was much better back in the Bronze Age.

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