The K-T Extinction

An impact at Chicxulub, where the target rocks contain high quantities of sulfur, produces enormous amounts of sulfate aerosols in the atmosphere that act as nucleation sites for acid rains much more intense and devastating than anything we have generated from industrial pollution. One model suggests rain with the strength of battery acid! The direct effect is enough to suffocate some air breathers, to destroy plant foliage, and to dissolve the shells of marine creatures living along shores and in the surface waters of the ocean. The balance of CO2 between air and ocean is upset, and a chain of climatic events makes ocean surface waters barren for perhaps 20 years. Among other effects of the impact, dust, smoke, and aerosols cut down the sun's rays for weeks or months, so that land plants and algal plankton in the ocean cannot photosynthesize. The dust also causes freezing air temperatures within days after the impact, and maintains them below freezing for weeks or even months. This may not be an unusual situation at a pole, and may not be a problem for an organism living deep in the ocean, but it is a catastrophe for organisms on continental land masses. Later, once the dust and aerosols have settled out, the enormous amount of CO₂ released into the atmosphere by the impact generates a greenhouse effect that elevates temperatures on Earth for a thousand years or more.

University of California at Berkeley, The K-T Extinction, 1999