Earth & Environmental Science Journalism:

Science Research Project


Did ionizing cosmic radiation during the Laschamp Event cause the Australian megafaunal extinction at 46,400 B. P.?

Curtis Brainard


A reconstruction of the D14C record between 40 and 50 kya was used to calculate the expected dose of ionizing radiation at sea level during the Laschamp geomagnetic excursion.  Despite the temporal coincidence between that event and the Australian megafaunal extinction, increased exposure to ionizing radiation is an unlikely explanation of the extinction.  Nonetheless, fossil corals from Araki Island, Vanuatu provided valuable new information about gaps in the existing D14C record.  New data points from nearly “carbon dead” samples show that D14C was near modern values just before the beginning of the Laschamp Event.


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Last updated: 8 January 2001, KAK.