Asteroid impact effects on Snowball Earth

Abstract

Several Snowball Earth periods, in which the Earth has been (almost) totally glaciated, are known from Earth history. Neither the trigger for the initiation, nor the reason for the ending of such phases, are well understood. Here we discuss some mechanical effects of the impact of asteroids 5–10 km in diameter on the Snowball Earth environment. An impact of this scale is the largest impact that is statistically predictable for 10–60 Myr time periods. The impact cratering itself (shock waves, impact crater formation) is not powerful enough to change the natural climate evolution path on Earth. However, the products of impact (mainly—water vapor) can be quickly distributed over a substantial part of the globe, influencing the global circulation (e.g., facilitating cloud formation). It is a question for future studies to confirm if such an event (which is possible statistically during this interval) may or may not have influenced the global climate of the Snowball Earth, and/or contributed to deglaciation.

Precise radiometric age establishes Yarrabubba, Western Australia, as Earth’s oldest recognised meteorite impact structure

“…However, ejection of high-altitude water vapour has potential for greenhouse radiative forcing, depending critically on atmospheric residence time 50 . Nonetheless, uncertainties in the structure and composition of Earth's Palaeoproterozoic upper atmosphere mean that the precise nature of atmospheric interactions of the collapsing vapour plume is inherently difficult to model 50 . Nevertheless, considering that Earth's atmosphere at the time of impact contained only a fraction of the current level of oxygen 51 , a possibility remains that the climatic forcing effects of H 2 O vapour released instantaneously into the atmosphere through a Yarrabubba-sized impact may have been globally significant.…”

Earth's Impact Events Through Geologic Time: A List of Recommended Ages for Terrestrial Impact Structures and Deposits

“…A similar biodiversification effect among fossil plankton was also proposed for the Acraman impact in the Ediacaran (Grey et al, 2003), a time when more highly organized organisms emerged (e.g., Knoll et al, 2006); stratigraphic and isotopic age constraints for the Acraman impact are, however, relatively imprecise (Schmieder et al, 2015b). Recently, Erickson et al (2019aErickson et al ( , 2019b suggested the *2.23 Ga Yarrabubba impact in Western Australia, which potentially affected a Paleoproterozoic ''Snowball Earth,'' may have been a trigger mechanism for the release of large amounts of water vapor into the atmosphere (Kring, 2003), thereby creating a warming effect that may have helped Earth escape its icehouse state (see also Koeberl et al, 2007b;Koeberl and Ivanov, 2019).…”

Asteroid shower on the Earth-Moon system immediately before the Cryogenian period revealed by KAGUYA

“…To date, the impact history and subsequent effects on the environment in the Neoproterozoic and Cryogenic have not been understood because terrestrial craters are not well preserved due to erosion. Koeberl and Ivanov 41 recently discussed the mechanical effects of one impact of an asteroid 5–10 km in diameter on the Snowball Earth environment, suggesting that the products of impact (mainly water vapour) could be quickly distributed over a substantial part of the globe, influencing the global circulation (e.g., facilitating cloud formation), because one impact cratering event (shock waves and impact crater formation) might produce much dust that entered the atmosphere and might have caused albedo changes. Recently, Schmitz et al 11 noted that the Ordovician meteorite shower should have triggered the mid-Ordovician ice age based on the sizes of the remaining terrestrial craters.…”