IMPACT MELTING OF FROZEN OCEANS ON THE EARLY EARTH - IMPLICATIONS FORTHE ORIGIN OF LIFE

Without sufficient greenhouse gases in the atmosphere, the early Earth would have become a permanently frozen planet because the young Sun w as less luminous than it is today. Several resolutions to this faint y oung Sun-frozen Earth paradox have been proposed, with an atmosphere r ich in CO2 being the one generally favored. However, these models assu me that there were no mechanisms for melting a once frozen ocean. Here we show that bolide impacts between about 3.6 and 4.0 billion years a go could have episodically melted an ice-covered early ocean. Thaw-fre eze cycles associated with bolide impacts could have been important fo r the initiation of abiotic reactions that gave rise to the first livi ng organisms.