Elisabetta Pierazzo

NASA Exobiology

Impacting and environmental catastrophes: investigating the effects of impact events on the climate system

An environmental catastrophe occurs when abrupt changes in the environment lead to an increased mortality of living organisms that may culminate in a mass extinction. This may have happened as a result of the Cretaceous/Paleogene boundary impact event. Environmental catastrophes that do not culminate in mass extinction events are much more difficult to identify in the geologic record. Therefore, we cannot identify potentially important environmental effects associated with other impact events recorded on Earth. Today¿s world is strongly affected by the rise of human civilization. Natural resources can barely support the world population, and we depend on the development of new technologies (genetically enhanced crops and livestock, alternative energy sources) to support our civilization. What would happen if an asteroid or comet struck the Earth¿s surface in the near future? While the Spaceguard Survey is close to identifying the majority of large Near Earth Asteroids, little specific work has been dedicated to the investigation of the potential environmental consequences of non-mass-extinction size impacts.

We want to use state-of-the-art three-dimensional climate models to investigate quantitatively the environmental and climatic perturbation associated with the impact hazard. The main goals of the proposed work are to:

1) Model the impact of potentially dangerous asteroids and/or comets between about 300m and 2km in diameter. The simulations will provide estimates of the amount and distribution of material ejected and deposited in the atmosphere.

2) Model the perturbation of atmosphere¿s radiative, dynamic and chemical state following the injection of impact-related material and energy, and investigate the relative perturbation of the climate system, and in particular the hydrologic cycle, over time.

3) Assess the atmospheric and climatic perturbations associated with the large K/P impact event. In particular, we wish to re-address the short-term perturbation of the atmosphere¿s dynamics and chemistry from energy, dust, water and CO2 loads.