File this under, 'how climate shaped history, and not the other way around'. ;') Glad to see another catastrophist here.
The 4200 year figure is in accord with the information in the earlier article,
Disaster that struck the ancients and these other links date from before the discovery of the ancient impact crater in Iraq. I read it a few years ago, but you've also linked it
here. There are further links on that BBC page to the stalactite/stalagmite studies that should be required reading for anyone concerned about so-called global warming.
How Climate Shaped History
by Kenneth Chang
In 2280 B.C., a civilization called the Akkadians absorbed Tell Leilan. A century later, the town had emptied out and remained unpopulated for three centuries. The entire Akkadian civilization collapsed and disappeared. "There is a depopulation, desertion of northern Mesopotamian region," says Harvey Weiss, professor of prehistorical archaeology at Yale University, who led excavations at Tell Leilan, "and Tell Leilan’s abandonment is simply typical of that process." Climate records show rainfall dried up in the Middle East around 2200 B.C., which would have deprived farmers of needed winter rains. In cores dug up in the Gulf of Oman to the south, sediments deposited during this time show very different minerals, indicating different wind patterns. Other archaeological sites show that cities to the south, surrounded by irrigated fields, swelled in population at the same time.Causes And Effects Of The 2350 BC Middle East Anomaly
by Marie-Agnès Courty
Test on various late third millennium BC archaeological deposit and contemporaneous provides evidence for the regional occurrence in northern Syria of a layer with an uncommon petrographic assemblage, dated at ca. 2350 BC (transition between late Early Dynastic and Early Akkad)... All these particles are only present in this specific layer and are finely mixed with mud-brick debris or with a burnt surface horizon in the contemporaneous soils. In occupation sequences, the layer displays an uncommon dense packing of sand-sized, very porous aggregates that suggests disintegration of the mud-brick construction by an air blast. In the virgin soil, the burnt horizon contains black soot and graphite, and appears to have been instantaneously fossilised by a rapid and uncommon colluvial wash... The restricted occurrence... suggests that the massive tephra accumulation can no longer be considered as a typical fallout derived from the dispersion of material from a terrestrial volcanic explosion... The theory of the Akkad empire collapse has, however, lost its basis.Meteor clue to end of Middle East civilisations
by Robert Matthews, Science Correspondent
"Studies of satellite images of southern Iraq have revealed a two-mile-wide circular depression which scientists say bears all the hallmarks of an impact crater. If confirmed, it would point to the Middle East being struck by a meteor with the violence equivalent to hundreds of nuclear bombs.
"The catastrophic effect of these could explain the mystery of why so many early cultures went into sudden decline around 2300 BC. They include the demise of the Akkad culture of central Iraq, with its mysterious semi-mythological emperor Sargon; the end of the fifth dynasty of Egypt's Old Kingdom, following the building of the Great Pyramids and the sudden disappearance of hundreds of early settlements in the Holy Land."
To put the impact into some perspective, the Barringer or Meteor Crater in AZ is about 3/4 mile across; this more recent crater would be the result of an impact more than four times greater.
Comets Tied To Fall Of Empires
by Robert S. Boyd
(1999)
At least five times during the last 6,000 years, about 3200 BC, 2300 BC, 1628 BC, 1159 BC, and between 530 and 540 AD, major environmental calamities undermined civilizations worldwide. Some researchers say these disasters appear to be linked to collisions with comets or fragments of comets like the one that broke apart and smashed into Jupiter five years ago this summer.
The civilization-shattering events of the historic era "must have been near-misses, because if we had been hit by a full-blown comet in the past 10,000 years or so, we wouldn't be here today," said Mike Baillie, a British archaeologist who studies tree rings.
Uh, no. Not near-misses. Not all objects in space are the same size.