This paper from five years ago seems consistent with the Hiawatha Impact Crater.
Some 13,000 years ago, as the last Ice Age seemed to lose its cold grip on the Earth, the temperature suddenly plunged again.
Up to now, scientists believed that the Younger Dryas cold reversal was caused by great amounts of Canadian meltwater flowing out into the North Atlantic and cooling it after an ice barrier collapsed upstream from the St Lawrence Valley.
Now the latest research indicates that it was not meltwater from Canada that triggered the Younger Dryas cooling (see Factbox). According to a new study, this was caused by icebergs and meltwater from Greenland.
Greenland icebergs may have triggered the Younger Dryas, September 13, 2013