I came across a well-researched and informative blog today summing up the recent findings and YDB science to date. I was so impressed by Abby Tabor’s post at Science Works Now, “New Evidence for Climate-Changing Cosmic Impact,” I have added a permanent link to her on the side-bar.
Tabor it seems was driven — shudder — to actually contact the authors on each side of the YDB hypothesis debate and ask them what they think. She has informative communications from both sides:
Their nanodiamond analysis also suggests a later origin for these particles, based on their position in the layer and their physical association with glass-like carbon, a product of wildfire. van Hoesel concedes that the nanodiamonds could have formed earlier and only later become stuck to the other carbon particles, although she considers it unlikely. She speculates that perhaps an as-yet-unknown process exists for the formation of nanodiamonds at the relatively low temperature of a wildfire. This has been observed in experimental set-ups; if the phenomenon could be found in nature, it might offer an alternative to the cosmic explanation.
Richard Firestone, one of the originators of the impact hypothesis, is not in the least deterred by the Dutch study. He claims their carbon-14 dates are “unacceptably precise”; if the error were larger, as he feels it should be with this technique, both groups’ dates would coincide. According to van Hoesel, though, the error is in line with other studies published in the field. The disagreement shows the importance of careful analysis of the numbers. Firestone also contends that, had the two groups used the same system of radiocarbon date calibration, the dates assigned to the impact and the Dutch wildfires would have been nearly identical. “In my opinion the van Hoesel paper supports our research. They find nanodiamonds at or near the date of the YD impact. There is no other accepted theory for the formation of nanodiamonds found in a narrow layer around the world. No nanodiamonds are found significantly above or below the YD layer. van Hoesel misinterprets the distribution of nanodiamonds near the YD which is affected by [stirring up] of the sediments by wind and rain. Typically nanodiamonds tend to rise in the sediment appearing a bit younger than they are.” Firestone finds that “most of our critics first confirm our work and then try to ascribe it to nebulous other causes.”
A 2011 article, “The Younger Dryas Impact Hypothesis: A Requiem” traces the history of this research and purports to put the question, finally, to rest. However, Ted Bunch, co-author of the impact hypothesis and former Chief of Exobiology at NASA Ames Research Center, observes that this scientific memorial service “presented little original evidence. Rather, they criticized non-peer reviewed documents. Their arguments were answered rather well”, he adds, by the 2012 paper from Israde-Alcántara I, et al., providing evidence from central Mexico in support of the proposed Younger Dryas cosmic impact.