Terrestrial effects of possible astrophysical sources of an AD 774‐775 increase in 14C production. Issue 6 (26th March 2013)

• Record Type: Journal Article
• Authors: Thomas, Brian C.; Melott, Adrian L.; Arkenberg, Keith R.; Snyder, Brock R.
• Is Part Of: Geophysical research letters. Volume 40:Issue 6(2013:Mar.)
• Page Start: 1237
• Page End: 1240
• Publication Date: 2013-03-26
• Subjects: solar proton event -- ozone -- carbon‐14; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/grl.50222
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: [1] We examine possible sources of a substantial increase in tree ring 14 C measurements for the years AD 774‐775. Contrary to claims regarding a coronal mass ejection (CME), the required CME energy is not several orders of magnitude greater than known solar events. We consider solar proton events (SPEs) with three different fluences and two different spectra. The data may be explained by an event with fluence about one order of magnitude beyond the October 1989 SPE. Two hard spectrum cases considered here result in moderate ozone depletion, so no mass extinction is implied, though we do predict increases in erythema and damage to plants from enhanced solar UV. We are able to rule out an event with a very soft spectrum that causes severe ozone depletion and subsequent biological impacts. Nitrate enhancements are consistent with their apparent absence in ice core data. The modern technological implications of such an event may be extreme, and considering recent confirmation of superflares on solar‐type stars, this issue merits attention. Key Points: AD 774‐775 14C spike may be explained by solar event Implication for greater likelihood of Significant atmospheric effect but no mass extinction