This regime can be and has been disturbed by volcanism, ranging from a couple of years to the 1159 BCE catastrophe extreme which blocked summer growth for eighteen years and appears to have collapsed the European Bronze Age culture and destroyed Atlantis.
It is my conjecture that the cause of major cooling is occasional volcanism and that it will be possible to link the global tree ring data for the past 10,000 years to individual major volcanic events. This is not a new conjecture, but my position is that it is now the strongest.
This also places the little ice age in its proper perspective. It was a sustained solar minimum and informs us of the worst that can be delivered from that quarter. The question remains as to whether there was a major volcanic event that initially worsened the effect. I do not think that such would have been missed. These events have to be big and messy and they do fill the atmosphere with dust somewhere. Confusing the issue is the claim that there was an increase in volcanic activity at the time, but this likely reflects the age of exploration and the attendant increase in eyeballs.
We can make this finding because of the apparent power of the volcanic mechanism as compared to all other mechanisms that have been trotted out. Solar variation is only good for gradual movement in either direction within the proscribed two degree range.
Ocean currents are also looking like also-rans because of their vast stability and that impact on the atmosphere is at best a surface effect that acts as a stabilizing heat sink.
None of these are contenders for an eighteen year long crop failure.
What I have just said about the obvious variables, also applies to novel hypothesis such as the CO2 idea. Whatever its merits, it is simply subsumed in the background noise that currently includes a global temperature recovery to the optimum.
The important question to ask was always to ask what caused the temperature to precipitously decline from time to time.
Right now, I have learned to respect the inherent stability of the global weather regime and its power to make real adjustments to the overall climate. I also find that the two hemispheres are much more independent of each other that I would ever have surmised. I would like to discover a strong atmospheric mechanism for shifting heat from the north to the south.
It is within our technical capabilities to establish a tree ring data set back to the Pleistocene Nonconformity and also link both northern and southern sets to the ice core data. It is a challenge well worth achieving, knowing that quality will persistently improve as it has over the past decades.
The Holocene record begins with the geological event that ended a million year Panama induced northern ice age and is so far clearly punctuated by one major volcanic event that lasted twenty years. Uncovering the volcanic causation of cooling events will be at least a dated foundation of global history of the Holocene and will allow archeology to hang their discoveries on a supporting historic framework. This will also provide the necessary data to prove up the conjecture beyond any reasonable doubt by supplying a data set large enough to apply statistical tests.
This item helps underline the wide reaching impact of Icelandic Volcanism.
Icelandic volcanic eruption caused 18th century Egyptian famine
Washington, Feb 09: A study by three scientists from Rutgers, The State University of New Jersey and a collaborator from the University of Edinburth, Scotland have found that an a volcanic eruption that killed around 9000 people in Iceland in the late 18th century, brought a famine to Egypt that reduced the population of the Nile Valley by a sixth.
The scientists used a computer model developed by NASA's Goddard Institute for Space Studies to trace atmospheric changes that followed the 1783 eruption of Laki in southern
"Our findings may help us improve predictions of climate response following the next strong high-latitude eruption, specifically concerning changes in temperature and precipitation. Given the sensitivity of these arid regions to reductions in rainfall, our predictions may ultimately allow society time to plan for the consequences and save lives,” said
He said while it was known that eruptions of volcanoes in the tropics produced warmer winters in the northern hemisphere, the new study had demonstrated for the first time that volcanic influences can also flow north to south, generating an array of repercussions, including both hot and cold weather.
He said the "new evidence, from both observations and climate model simulations" showed that high-latitude eruptions had altered northern hemisphere atmospheric circulation in the summer following, with impacts extending deep into the tropics.
Historical records show that in June 1783, the Laki volcano began a series of eruptions, regarded as the largest at high-latitude in the last 1,000 years. The eruptions produced three cubic miles of lava and more than 100 million tons of sulphur dioxide and toxic gases, killing vegetation, livestock and people.
These eruptions were followed by a drought in a swath across northern Africa, producing a very low flow in the
“In the northern hemisphere, the summer of 1783 was chilly – the coldest in at least 500 years in some locations, according to tree ring data. Sulphate aerosols in the atmosphere kept the warmth of the sun from the Earth's surface,” Volney added.
“With little or no monsoon, there were no clouds to bring rain for the rivers or shield the surface from evaporation. Little or no rain, no irrigating floods, no crops and no food – all conspired to bring about the situation Volney described, and all were traceable back to Laki,”
The findings were published in the September 30 issue of the Geophysical Research Letters, and now features online at NASA’s website.