I realize that this subject is distasteful to many because of the early false claims. But the
new evidence suggests that there was some kind of extraterrestrial impact. Hence it should be given further study.
I remember pleading with Science’s Richard Kerr to do a piece on this discovery. He thought about it and decided that, as he had written a very negative piece about the original idea, he didn’t want to revisit the subject.
Although I don’t for a minute believe that this impact did in the mammoths and the Clovis people, I do think that it triggered the YD.
What a significant and pleasing development. Wally Broecker has endorsed a cosmic impact as the cause of the Younger Dryas cold period. Broecker is a father of modern climate science (and pictured above with the Tusk at my heaviest in 2009).
“Most people were trying to disprove this,” said Wallace Broecker, a geochemist and climate scientist at Columbia University’s Lamont-Doherty Earth Observatory. “Now they’re going to have to realize there’s some truth to it” – though maybe only a spherule or two.
Put aside the gratuitous author shot following the quote, and you can see that by 2013 Broecker had sweetened on our favorite wild theory.
The star of the event was Wally Broecker of the Department of Earth and Environmental Sciences at Columbia University. Broecker is one of the most respected environmental scientists in the world. Credited with first describing the ocean current conveyer belt and inventing the term “global warming,” his honors include membership in the National Academy of Sciences and award of the Presidential Medal of Science. His presentation was sober and low key, but he made it clear that he was unconvinced by the evidence for an impact or any catastrophic change at the YD boundary. But rather than condemning the hypothesis, he stated simply that the decline in the North American megafauna could be understood as a result of climate change and overhunting—the conventional explanation. Broecker said, “We do not need the impact hypothesis.”
So. What are we to make of the progression of Wallace Broecker, from public skeptic, to private encouragement, to highly personal endorsement of a cosmic cause for his iconic example of abrupt climate change?
Well, Wally himself tells the story best in his ‘brief’ below, and it seems to be an old one: The scientific method worked and a preeminent expert was slowly but surely convinced by overwhelming evidence for the impossible.