Largo, FL 33770
June 17, 2012

to be posted on

750 3rd Avenue
5th floor
New York, NY 10017

Every time I have read about the arctic in recent years (your excellent special section in The Melting North ECONOMIST vol. 403 no. 8789 June 16, 2012 following page 52 for instance) it is with a single question.  Grant me that now air rises in the warm tropics and sinks at the cold poles.  Grant me that some time between 90 days and 90 years from now the North Polar ice cap will be gone.  At that time the sun at the solstice, somewhat less than 30 degrees above the horizon at the North Pole, will deliver half of the energy to the surface that it does at noon at the equator during the equinox.  But the sun is not always overhead at the equinox.  It is usually lower during the twelve hour day.  Add to that the fact that sea water absorbs almost all incoming energy while ice reflects almost all and the fact that land reflects something in between, and there is significant land at the equator and none at the north pole, and we have – cloud cover aside – more energy entering the Arctic Ocean than any place on earth now.  So air will be going up at the North Pole and coming down at the South Pole.  Things will be different.

Starting with high altitude air at the equator then, air will mosey southward much as it does now, carrying little moisture, and descend over the Antarctic.  Thence it will move north to the equator but then instead of rising and dumping its moisture it will continue north, warming and drying all the way to something like the Arctic Circle.  There it will rise, drop its moisture and return south.  Since this is the equivalent of a summer thunderstorm in the temperate zone, it will drop hail.  This storm will draw not from an area perhaps a hundred miles across but from the whole globe so the hailstones may be larger than we have seen.  Precautions will be needed for anybody going there.

I see two possibilities.  Probably the air will return over the whole area in the shape of an umbrella and high latitudes will have a lot of cold rain, which will be quite endurable given tight houses and nice scratchy woolens. 

But possibly the amount of air will be too great to accommodate at high altitude.  The result will then be a corridor of hail storm reaching far to the south.  There could be so much hail that a layer of ice survives not only the coming winter but the following summer.  Instead of inches of rain there could be many meters of ice as a significant part of the precipitation for the whole planet falls in a rather small zone. 

Cloud cover should ameliorate that problem if the storm spreads in all directions.  A corridor would leave the Arctic Ocean mostly exposed to the stare of the sun, and away from the catastrophic ice fall the northern hemisphere would get little or no precipitation. 

So which is it to be?


M. Linton Herbert

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