Climatic effects of an impact-induced equatorial debris ring

Abstract

[1] Several theoretical and laboratory studies suggest that some large impact events are capable of inserting material into space depending on mechanics of the impact. This material would quickly coalesce to form a temporary debris ring in orbit around the equator, which would cast its shadow on the winter hemisphere. The results of an atmospheric general circulation model (GCM) simulation where an orbiting equatorial debris ring is applied as a boundary condition to the model show how the longer-term effects of a major impact could affect the climate system. The primary effect is a severe cooling in the tropics and the subtropics, especially under the seasonally migrating ring shadow. The globe cools and becomes drier, with the exception of monsoonal regions that become wetter. The Hadley cell is weakened resulting in drier tropics and weaker subtropical high-pressure cells in the winter hemisphere. Because the tropics cool more than middle latitude regions, the equator-to-pole temperature gradient becomes shallower resulting in weaker tropospheric winds and less high-latitude storminess. We suggest that the late Eocene impact(s) (35.5 Ma) could have generated a geologically temporary orbiting debris ring based on the global distribution of tektites associated with these events and patterns of climate change immediately above the iridium/microtektite layer. The Cretaceous-Tertiary boundary event, while larger, did not produce a debris ring. We also suggest that an opaque debris ring could have acted as the trigger to at least one episode of global glaciation during the Neoproterozoic.