IMPACTS ON THE EARTH BY ASTEROIDS AND COMETS - ASSESSING THE HAZARD

[摘要] There is a 1-in-10,000 chance that a large (approximately 2-km diameter) asteroid or comet will collide with the Earth during the next century, disrupting the ecosphere and killing a large fraction of the world's population. Although impacts of this magnitude are so infrequent as to be beyond our personal experience, the long-term statistical hazard is comparable to that of many other, more familiar natural disasters, raising the question of whether mitigation measures should be considered.

[关键词] CRETACEOUS-TERTIARY BOUNDARY;NUCLEAR WINTER;RISK;AGES