Scientists from Royal Holloway College (part of London University) in association with Sandia National Laboratory in the US, and 13 other universities in N America and Europe are down as contributing to the conclusions, are all unanimous in saying a large impact or airbursting comet or asteroid is out of context in explaining the sudden dip in climate at the Younger Dryas boundary and even less in respect of explaining the disappearance of Clovis points and their replacement by the similar Folsom points (which appear derivative). They add, somewhat inconclusively, that other explanations must be found to explain the disappearance of Clovis culture – without mentioning the demise of the large mammals on which they preyed (at least, not in the abstract). The research was published in the Geophysical Mongraph Series – see for example www.pasthorizonspr.com/index.php/archives/01/2013/clovis-culture-comet-c… and http://phys.org/print278758901.html and http://phys.org/print278759528.html
The big name in this is Mark Boslough, and there is something like a bit of hero worship involved in his physical description as provided by the press release. He is one of the leading researchers into comets, air bursts, and cosmic intrusions, a name that pops up in research into the Tunguska object for example. Reading between the lines one can see that the critiques of the YD boundary impact have gone out of their way to get him onside and he may have been miffed by use of his methodology by the pro- YD boundary eventers. This appears, on the face of it, to be another attack on the latter by the former without producing any firm evidence to support their case – only that it was not an impact or a comet exploding in the atmosphere. The YD boundary event people have since moved on from that position and have been thinking in terms of the Earth encountering a dense stream of material left behind by the passage of a comet. Simply by regurgitating the obvious, no evidence of a crater, is a waste of time and will not deter the supporters of the hypothetical YDB event – which must cause one to think of another explanation for this paper. It is quite clearly aimed at the general public, hence the engineered press release, following a series of articles in science organs and by the Nova television people – and has absolutely nothing new to say. Apart from Boslough's input.
However, that is not to say they are suppressing genuine science as the YDB event clearly has major problems – not least the fact it resembles the so called Heinrich events which litter the last Ice Age. In addition, ice cores would clearly show some sort of anomaly associated with the boundary event but so far it is the increase in dust on the Greenland ice sheet that remains top of the list. Dust can have terrestrial origins and is therefore not conclusive – unless it can be shown to be extra terrestrial in origin. No doubt supporters of the comet connection are eagerly beavering away and will address these issues over time. Not the last word – a long way from that.
Boslough et al (editors) 'Climate Landscape and Civilisations' Geophysical Mongraph Series volume 198 (2012) (pubished in January 2013)