An excellent run down of the complex climate changes after the end of the recent great Ice Age. Personally, I am inclined to think the several of the major ice ages were caused by major terrestrial events. The Long Valley and Yellowstone megavolcanic events over 700,000 and 600,000 year ago come to mind. On the other hand I would not be surprised if others were begun by major boloid events. I think Firestone et al give an excellent easy to read account of events that may have caused the Younger Dryas. As one comment points out there could have been several such events relatively close in time.
The great Chesapeake Meteor event around 34 million years ago was one of several in that period. A ten mile diameter crater was found of that age off Toms River, NJ. Also Popogai (sp?), a 60 mile diameter crater in Russia has that age. On the other hand while the most recent ice age began about 125,000 ya, around 74,000 ya the megavolcano Toba left a crater 18 by 65 miles and the charts show a major downturn in temperature for that period.
In Egyptian history there is a period of perhaps 200 years prior to 2,000 BC known as the First Intermediate Period, documented in the Ipuwer papyrus housed in the Leyden (sp?) Museum. Checking on craters, I found that there were a number of significantly large boloid craters (from 5 to 14 miles in diameter) in Argentina with the right age for that period. SC has reported on the 2 mile diameter crater found in the drained Iraq Marshes also about 2,000 BC.
Detail on the eruption of Laacher See Volcano in Germany, 12,900 ya is well described in Hans-Ulrich Schmincke’s book Volcanism (2004). This Plinian eruption was slightly larger than Pinatubo. In other words there are potential a number of potential interactive forces at work influencing the Younger Dryas.
While, I think that a lot more needs to be known and worked out scientifically about anthropogenic climate influence, I think the basic thing we have to realize is that there are a number of possible potential influence on climate. Since highly educated scientists tend to be experts on volcanoes, cosmic events, climate, archaeology, or ancient history, etc, we have lacked a fully functioning interdisciplinary approach to answering such complex questions. One of the things I love about both Catastrophism and GGG is that these sites bring together a number of gifted and curious amateur science sleuths.