There was a paper in Science last week that has gotten quite a bit of press. It reports further evidence in support of the idea that the Younger Dryas — a distinct period towards the end of the last ice age when the deglaciation in the Northern Hemisphere was interrupted for a period of about 1300 years — was caused by a barrage of comets hitting North America.
When the first papers on this came out last year, we expressed skepticism. We remain skeptical and our reasons remain unchanged. But we think it is worth saying a bit more on this, because the reporting on this issue has largely ignored just how big an idea this is, and therefore how much more work would need to be done before it could be taken very seriously.
[Read more…] about The Younger Dryas comet-impact hypothesis: gem of an idea or fool’s gold?
I often receive letters that range from amusing claims that we are overlooking changes in the magnetic field, to tales about how the “weight” of carbon dioxide keeps it “near the ground”. If the writer sounds serious, then I treat them seriously, and do my best to provide a helpful reply. Often, though, I find myself in a pointless debate of the most basic, well-established physical principles. I generally cut off the discussion at this point, because I simply don’t have the time. This can result in a hostile response accusing me of “having an agenda”. Most would call me naïve for bothering to respond in the first place.