Graham Hancock on science: what the evidence says · JRE #1284
“we get a group of more than 60 major scientists who are seriously proposing that the Earth was hit by multiple fragments of a giant comet 12,800 years ago, and that this caused a huge rise in sea level and extinctions of megafaunas”
What the evidence says
The Younger Dryas Impact Hypothesis (YDIH), first proposed in 2007, holds that fragments of a disintegrating comet struck or exploded over North America roughly 12,800 years ago, triggering abrupt cooling, and it has since been championed by a recurring group of several dozen co-authors across a series of papers. However, the hypothesis has faced sustained rejection from most of the geoscience community: independent research teams have repeatedly failed to replicate key evidence such as nanodiamonds, magnetic microspherules, and platinum anomalies at claimed impact sites, no confirmed impact crater has ever been identified, and mainstream reviews attribute the era's cooling to disrupted ocean circulation from glacial meltwater rather than an extraterrestrial impact. Megafauna extinctions across this period are attributed by most paleoecologists primarily to a combination of climate change and human overhunting, not a sudden comet strike, and no mainstream evidence supports a "huge rise in sea level" caused by an impact at this time. Underscoring the hypothesis's continuing evidentiary problems, a 2025 paper reporting new marine-sediment support for the YDIH was retracted by PLOS ONE in 2026 after outside experts raised concerns about its referencing, methodology, and data reporting. The YDIH therefore remains a real but minority position advanced by a specific, persistent research group, not a broadly accepted finding within Earth science.
- RETRACTED: A 12,800-year-old layer with cometary dust, microspherules, and platinum anomaly recorded in multiple cores from Baffin Bay · journal
- A Blind Test of the Younger Dryas Impact Hypothesis · journal
- Independent evaluation of conflicting microspherule results from different investigations of the Younger Dryas impact hypothesis · government