Bolide Impacts and Climate
The coincidence of a large asteroid or comet (bolide) impact with the mass extinction of life that occurred at the Cretaceous/Tertiary (K/T) boundary (65 million years ago) suggests that the extinctions were caused by climatic and environmental changes triggered by the impact event (Alvarez et al., 1980; Toon et al., 1997). A number of possible mechanisms of impact-induced climatic change have been proposed, including the direct effects of: atmospheric dust produced by the impact; soot from wildfires triggered by the initial blast and by ejecta re-entering the atmosphere; water vapor injected into the upper atmosphere by oceanic impacts; the creation of NO and HNO3acid rain; sulfuric acid aerosols derived from anhydrite deposits in the target rocks; and carbon dioxide released from limestone in the target. Indirect effects on climate could come from major perturbations of the global carbon and sulfur cycles generated by the mass extinctions, and related ecological perturbations...
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