Join Hugh Ross in this breaking News of the Day episode of Stars, Cells, and God. Hugh describes the discovery of microspherules and meltglass at three North American sites, consistent with low-altitude airbursts from a disintegrating comet, that explain the Younger Dryas cooling onset 12,800 years ago.
Bolide Airbursts Trigger Recent Global Cooling Event
- During the younger Dryas (12,800–11,700 years ago), global mean temperatures plummeted by 10–15°C. This cooling event, in part, explains the unprecedented climate stability that persisted from 9,500 to 75 years ago.
- Geologists had cited the Hiawatha Impact Crater in northwestern Greenland as evidence for an asteroid impact that caused the younger Dryas cooling event.
- Recently, physicists disputed the claimed 12,800 years ago date for the Hiawatha Crater, citing argon-argon and uranium-lead dating of zircon crystals that yielded a melt date of 57.99±0.54 million years ago.
- 26 scientists report their discovery of microspherules, meltglass, nanodiamonds, and combustion aerosols, consistent with them being caused by low-altitude airbursts, at sites in New Jersey, Maryland, and South Carolina.
- The microspherules, meltglass, and nanodiamonds all have radiocarbon dates of 12,835—12,735 years ago. The implied melt temperatures range from 1,250°C to 3,053°C.
- The high-temperature, high-pressure shock waves generated by low-altitude airbursts from a disintegrating comet would explain the Younger Dryas Cooling Event and the accompanying multi-continent megafaunal extinctions but would not necessarily leave behind any discoverable impact craters.
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