An attempt to stimulate discussion about the causes of an unexpected event which occurred after the huge eruption of Tambora Volcano in 1815
Guest Essay by Caleb Shaw
Volcanoes cause cooling, right? No.
Having got your attention, I would like to bring up three historical incidents, hoping I may generate some interesting explanations for something I myself have no definite answer to.
On April 10, 1815 the Tambora Volcano exploded. It is estimated it blew 39 cubic miles of ash skywards. (A three-mile by three-mile by three-mile cube is only 27 cubic miles.) (I have no idea how many Manhattans that is.)
The noise was so loud it was heard 1200 miles away. Ships over the horizon assumed it was the cannon of a ship in distress and sailed around looking for another ship, and on one island troops were marched off to reinforce other troops because it was assumed an outpost was under attack. Then the great cloud of ash began to spread across the sky.
It is estimated 10,000 people were killed immediately by the blast, as many as 70,000 more by starvation or diarrhea brought on by the heavy ash fall, and another 4600 by tsunamis ranging from six to thirteen feet. The blast, as large as four Krakataus, penetrated the tropopause, roughly 11 miles up near the equator, and reached 16 miles further into the Stratosphere, to a total height of 27 miles. There, high above the circulations of Haley and Ferrel Cells, it began to spread out around the Globe.
By June 28, 1815 the inhabitants of London were noting amazing, brilliant and long-lasting sunsets.
The following summer, 1816, was remarkably cold over many northern lands, marked by frosts and ruined crops. It is remembered as “The Year Without A Summer” and, in my neck of the woods, as, “The Year Of Eighteen Hundred And Froze To Death.” Here in New Hampshire, where hay was an export that fueled the horse-drawn transport big cities, not even enough grass could be grown to feel local livestock. While the wealthy could import hay from Pennsylvania, the poor knew hunger, and many simply had to slaughter their livestock. In the following years populations of many towns in New England shrank, as people never wanted to see such a summer again, and the rock-free lands of Ohio sounded warmer, and actually were further south.
The link between Tambora and that cold summer seems plain, but here comes the third and, to me, intreauging item from 1817. It involves a quote from John Daly’s site which many know well, that begins,
“It will without doubt have come to your Lordship’s knowledge that a considerable change of climate, inexplicable at present to us, must have taken place in the Circumpolar Regions, by which the severity of the cold that has for centuries past enclosed the seas in the high northern latitudes in an impenetrable barrier of ice has been during the last two years, greatly abated….”
This statement by the President of the Royal Society in London is dated November 20, 1817, and is not what I would have expected. I would have expected Tambora to increase the ice at the pole by making the entire earth colder. The fact the ice apparently decreased is a polar puzzle.
The question then becomes, “Do volcanoes reduce the amount of ice at the poles?”
In the comments at WUWT the commenter Philip Bradley suggested that Tambora’s ash may have fallen on the polar ice, reducing the albedo and increasing the melting. I’m not sure enough ash would fall, that far north, and remain uncovered by snow long enough, to have such a dramatic effect.
I’d be interested to hear the ideas of others. My personal guess is that, even though the climate was colder back then, the AMO still went through warm and cold phases, and just happened to be moving into a warm phase, involving a slosh of warmth moving north, and Tambora accentuated this slosh.
As I have explained elsewhere, “I call this my Slosh Theory, and it is based upon a highly scientific experiment I did at age three in the bath tub. Timing was everything. If you got the timing down, you could generate such a tremendous wave that half the water left the bathtub and wound up on the floor.
My mother did not appreciate my research and stunted my scientific growth, which explains why I became a writer.”