If a mass extinction-causing asteroid or comet impact happened in the last 15,000 years, we would know about it, right? Not quite... There is still major controversy about an impact that may or may not have occurred around 12,900 years ago. In this video, we discuss the hypothesis that an impact caused major climate change and extinctions around 12,000 years ago, which is called the Younger Dryas Impact Hypothesis (YDIH).
In a recent video (https://youtu.be/OWaOoTI1Bec?si=91Wjo_91vNuIawrJ), I covered the Pleistocene megafauna (e.g., mammoths, mastodons, giant ground sloths, etc) that lived from about 2.6 million years ago until around 11,000 years ago. Many species of megafauna went extinct around the same time during a rapid cooling event called the Younger Dryas. However, what caused the Younger Dryas cooling remains debated, which is the topic of this video. Some hypothesize it was an extraterrestrial impact (i.e., the YDIH), some hypothesize a super volcano erupted releasing massive amounts of ash that blocked sunlight and caused cooling, and some hypothesize that a change in ocean circulation (shut down of the AMOC) due to the preceding warming trend was the cause for the switch to global cooling. In this video, I cover these possibilities (mainly the impact & ocean circulation possibilities), the evidence behind them, and their likelihood based on current data. Hope you enjoy! ;D
0:00 What was the Younger Dryas?
1:11 When was the Younger Dryas?
2:55 Unknown cause of Younger Dryas?
3:58 YD Impact Hypothesis
4:55 Impact evidence
7:20 Missing evidence
10:21 Extinction of Clovis people?
11:31Extinction of megafauna?
13:02 Is there a crater?
14:21 Other causes of the YD cooling
15:04 Ocean circulation cause
18:43 Similar ocean circulation changes today
21:03 Summary of YD Impact Hypothesis
References:
Rethinking megafauna: https://royalsocietypublishing.org/doi/full/10.1098/rspb.2019.2643
Late survival of megafauna refuted for Cloggs Cave, SE Australia: Implications for the Australian Late Pleistocene megafauna extinction debate: https://www.sciencedirect.com/science/article/abs/pii/S0277379120307435
Relationships between climate change, human environmental impact, and megafaunal extinction inferred from a 4000-year multi-proxy record from a stalagmite from northwestern Madagascar: https://www.sciencedirect.com/science/article/abs/pii/S0277379120300573
Environmental drivers of megafauna and hominin extinction in Southeast Asia: https://www.nature.com/articles/s41586-020-2810-y
YDIH specific refs:
Holliday et al., 2023: https://doi.org/10.1016/j.earscirev.2023.104502
Powell, 2022: https://doi.org/10.1177/00368504211064272
Sweatman, 2021: https://doi.org/10.1016/j.earscirev.2021.103677
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