April 25, 2015
nobabies.net
Jennifer Francis
Rutgers
francis@imcs.rutgers.edu
Dear Professor Francis:
I would like to thank you for taking an interest in something that I think may be very important. (Eli Kintisch Into the Maelstrom SCIENCE vol. 344 no. 6181 April 18, 2014 250) I am far from my comfort zone but let me make bold to ask you a question. I shall post this on my web site one day, so I must add some background for the sake of the general reader. You may detect errors, which I would be most happy to post in an effort not to mislead. The question comes at the very end.
Considering only the northern hemisphere, by and large it is hot at the equator and cold at the North Pole. Hot air rises at the equator and cold air falls at the pole. That is not to say the same molecule of air traveled from the steaming tropics to the arid arctic before falling. But the energy in the air at the equator is impelled toward the pole. Air high in the temperate zone more-or-less turns with the earth and is drawn toward the pole but as it moves in that direction the coriolis effect (momentum of the air tends to keep it moving at the same speed toward the east but the earth below is traveling slower because the diurnal circle it describes is shorter as one gets closer to the pole) speeds it up relative to the surface, and this produces a river of air we call the jet stream.
The earth below is still more warmed by the sun that the pole, so the high air is dumping heat to the sky. Even though the air changes in volume and temperature as it rises and falls, there is always that excess heat content relative to the pole. Little actually reaches the pole.
The return trip is not simple either, but toward the end we have southward moving air at the surface lagging behind the ever faster surface, which is appreciated as the trade winds.
The arctic ice cap is melting. It starts to melt soon after the spring equinox and begins to refreeze around the fall equinox. This produces a sort of Maxwell’s demon, trapping the heat of the summer though the winter. The process is modified by ocean currents beneath, which I do not claim to understand. Some day we expect the North Pole itself to melt; it has already at least once been covered by a lake of melt water.
Now suppose there is some year a fluke combination of the current, black dust brought up to the ice cap by a meander of the jet stream and warm air brought up as well. The North Pole and the ice near it melt early, along with a great tract of the Arctic Ocean.
Now the sun is almost thirty degrees above the horizon. Remembering high school geometry, that means the insolation at the pole is half what it is at noon at the equator at the equinox. But the sun on that day at the equator is up only 12 hours. At the pole it is up 24 hours. So to a first approximation the pole is getting as much heat as the equator does at the equinox. It’s hot. It’s not warmer. It’s hot.
It gets worse. Even during the twelve hours of sunlight at the equator the sun is not always at the zenith. Now the North Pole at the solstice has the highest rate of incoming heat of any latitude. Compounding that, ice reflects 90 percent of the sunlight, sea water absorbs about 90 percent and land is somewhere in between. At the equator the earth is mostly water, but there is significant land. The North Pole is now really hot.
Hot air rises. The North Pole is the eye of a huge cyclonic storm drawing heat from the bulk of the northern hemisphere. Now the hot air “wants” to go, not to the equator, but to the South Pole. Since tropical air is distributed around the circumference of the earth it is no surprise that that the behavior of the air is rather docile. But hot air coming down from the pole is starting in a small area; if the jet stream is any model there is a river of air that goes south and west to the equator and then starts spiraling south and east. And don’t expect it to be very tactful.
How big will the hail stones be? One shudders. There used to be a now-debunked notion that frozen mammoths were found with unwilted flowers in their stomachs. I think, “That doesn’t prove anything,” is now the consensus. Maybe it took a long time for a mammoth to digest a flower. But that’s only a “maybe.” Maybe it didn’t.
When my father was a young man he took a then-audacious tour of the American West. He went on horseback to the Grasshopper Glacier. He described grasshoppers throughout the thickness of some thirty feet of glacier. I wish there was a lot of the glacier left. I would be happy to look at it with something like a polarizer to see if there were some clue that it was indeed formed of giant hailstones. Grasshoppers do a lot of amazing things, but I don’t think hopping around on ice or snow is part of their repertoire. The first guess would be that the glacier formed in a single day.
This is idle speculation. If it falls in your path you can taunt some tormentor by asking, “You think my claim that the jet stream seems to be slowing is extreme? There’s a blogger out there who says it might blow the other direction.”
Cloud cover might reduce some of the energy hitting the Arctic Circle, but I have always heard that the eye of the storm can be clear.
So the question is, “Can the area around the North Pole melt in the early summer, and if so, what will happen?”
Thank you.
Sincerely,
M. Linton Herbert MD
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