Climatic And Biogeochemical Effects Of A Galactic Gamma-Ray Burst
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Melott, Adrian L., Thomas, Brian C., Hogan, Daniel P., Ejzak, Larissa M., and Jackman, Charles H.,
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Abstract
It is likely that one or more gamma-ray bursts within our galaxy have strongly irradiated the Earth in the last Gy. This produces significant atmospheric ionization and dissociation, resulting in ozone depletion and DNA-damaging ultraviolet solar flux reaching the surface for up to a decade. Here we show the first detailed computation of two other significant effects. Visible opacity of NO2 is sufficient to reduce solar energy at the surface up to a few percent, with the greatest effect at the poles, which may be sufficient to initiate glaciation. Rainout of dilute nitric acid could have been important for a burst nearer our conservative "nearest burst". These results support the hypothesis that the late characteristics of the late Ordovician mass extinction are consistent with GRB initiation.