 Critics of the hypothesis have repeatedly addressed the responses, and have published counterarguments.Even though a 2018 paper that presented evidence for an impact crater of unknown age under the Hiawatha Glacier in Greenland did not suggest any connection to the Younger Dryas, some scientists speculated without evidence about such a link in news reports.Skeptics reject this connection because it would require an improbably recent impact — an impact of this size should occur only once every few million years — and it would leave evidence, such as a young ejecta blanket.