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Terrestrial Ozone Depletion due to a Milky Way Gamma-Ray Burst

The core information for this publication's citation.: 
Thomas, B. C., C. H. Jackman, A. L. Melott, C. M. Laird, R. Stolarski, N. Gehrels, J. K. Cannizzo, and D. P. Hogan (2005), Terrestrial Ozone Depletion due to a Milky Way Gamma-Ray Burst, The Astrophysical Journal, 622, L153-L156.
Abstract: 

Based on cosmological rates, it is probable that at least once in the last gigayear the Earth has been irradiated by a gamma-ray burst (GRB) in our Galaxy from within 2 kpc. We have performed the first detailed computation of the effects on the Earth’s atmosphere of one such impulsive event: A 10 s 100 kJ mϪ2 burst penetrates to the stratosphere causing globally averaged ozone depletion of 35%, with depletion reaching 55% at some latitudes. Significant depletion persists for over 5 years after the burst. A 50% decrease in ozone column density leads to approximately 3 times the normal UVB (280–315 nm; a wavelength band that ozone significantly absorbs and that living organisms are sensitive to) flux, and widespread extinctions are likely, based on extrapolation from sensitivity of modern organisms. Additional effects include a shot of nitrate fertilizer and NO2 opacity in the visible, providing a cooling perturbation to the climate over a similar timescale. These results lend support to the hypothesis that a GRB may have initiated the late Ordovician mass extinction (Melott et al.). Subject headings: astrobiology — gamma rays: bursts Online material: color figures, mpeg animation

Research Program: 
Atmospheric Composition Modeling and Analysis Program (ACMAP)