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Rod Chilton, author of the most recent (and perhaps only) comprehensive review of Younger Dryas science, was kind to contribute this fine critique of David Morrison’s recent paper in Skeptical Enquirer. I am reading Rod’s excellent book and look forward to reviewing it soon:
The debate continues as to the cause of the more than 1,000 year-long cold interval known as the Younger Dryas. Falling on the heels of the Last Ice Age, or more correctly immediately after the two warm intervals known as the Bolling and Allerod interstadials, the Younger Dryas onset appears now to have started in as little time as one to three years. The climate shifted that suddenly from near present day warmth to near Ice Age cold. A second important feature to be noted is that apparently most of the planet was affected, and that the teleconnection between various parts of the planet was swift. This suggests strongly that the forcing mechanism resided in the atmosphere, rather than in the Ocean (where a much slower teleconnection would have been evident). The Younger Dryas however was very different from another alleged cosmic encounter, that of the great Cretaceous extinction event of approximately 65 million years ago. At this time, a huge bolide struck the Gulf of Mexico. Likely measuring as much as ten kilometres’ across, the demise of the dinosaurs seems to have been assured.
However, the Younger Dryas cosmic event is envisioned as considerably different, that is if astronomers William Napier and Victor Clube are correct in their calculations. Drs, Napier and Clube believe that what is a far more likely type of encounter is best described as a “cosmic shower.” The nature of such an event would have a cosmic stream of already broken up comet and asteroid pieces striking earth, but extended over widespread areas as the influx took place more as showers than as single objects. All manner of sizes from very small through Tunguska-sized and finally on upwards to objects possibly one half kilometre wide or more pummelling planet earth. Thus the proof of such an encounter will despite being from a much less distant time, will nonetheless be somewhat more difficult to discern than was the case for the K/T dinosaur event.
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