A new paper authored by a large group of experts in domains ranging from Anthropology and Archaeology to Environmental Changes and Impact Cratering, published online this week in the well established journal Earth-Science Reviews, definitively refutes the Younger Dryas impact hypothesis (YDIH). The pseudoscientific Younger Dryas impact hypothesis made the news regularly since it was first put forwards by Firestone et al in 2007 in PNAS. It also generated a tremendous amount of discussions, controversies etc... and many many citations for its authors... (keep that in mind when you evaluatie scientific output).
This new extensive and detailed paper, scrutinises, evaluates and counters all the arguments advocated to support the YDIH for the last 15 years, it is authored by Vance T. Holliday; Tyrone L. Daulton; Patrick J. Bartlein; Mark B. Boslough; Ryan P. Breslawski; Abigail E. Fisher; Ian A. Jorgeson; Andrew C. Scott; Christian Koeberl; Jennifer Marlon; Jeffrey Severinghaus; Michail I. Petaev and Philippe Claeys.
Take home message: There is no evidence for comet or asteroid impact 12900 years ago and this has nothing to do with the Younger Dryas cooling or the Clovis culture in North America.
.... and this is not new read News in Science 30 Aug. 2010 article by Dick Kerr.