Start the new year off right with a new paper summarizing the evidence against a Younger Dryas impact event. Led by Mark Boslough, it was published in a recent Chapman Conference volume (Climates, Landscapes, and Civilizations) by the American Geophysical Union. You can read the abstract (subscription required for the PDF) here.
M. Boslough, K. Nicoll, V. Holliday, T. L. Daulton, D. Meltzer, N. Pinter, A. C. Scott, T. Surovell, P. Claeys, J. Gill, F. Paquay, J. Marlon, P. Bartlein, C. Whitlock, D. Grayson, and A. J. T. Jull. 2012. Arguments and evidence against a Younger Dryas Impact Event. In Climates, Landscapes, and Civilizations, Geophys. Monogr. Ser., vol. 198, edited by L. Giosan et al. 13–26, AGU, Washington, D. C., doi:10.1029/2012GM001209.