In two companion articles published in the Journal of Geology, an international team of more than 30 researchers have produced new results linking the Younger Dryas Period to a possible cometary impact. Geochemical evidence from more than 170 sites across the Earth points to a cometary impact at the onset of the Younger Dryas Period, ca. 12,800 years ago. High concentrations of platinum have been detected in ice cores from the Greenland Ice Sheet and a major peak in aerosols produced by biomass burning is recorded in sedimentary cores that date back to this time. These fires are estimated to have consumed as much as 9% of the total biomass of Earth.