title: Impact melting of frozen oceans on the early Earth:  implications for the origin of life.
abstract: Without sufficient greenhouse gases in the atmosphere, the early Earth would have become a permanently frozen planet because the young Sun was less luminous than it is today. Several resolutions to this faint young Sun-frozen Earth paradox have been proposed, with an atmosphere rich in CO2 being the one generally favored. However, these models assume 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 ago could have episodically melted an ice-covered early ocean. Thaw-freeze cycles associated with bolide impacts could have been important for the initiation of abiotic reactions that gave rise to the first living organisms.
authors.affiliation: Scripps Institution of Oceanography, University of California at San Diego, La Jolla 92093-0212, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Bada
authors.forename: C
authors.initials: C
authors.lastname: Bigham
authors.forename: S L
authors.initials: SL
authors.lastname: Miller
mesh_terms: D000596:Amino Acids; D001272:Atmosphere / Q000032:analysis; D002245:Carbon Dioxide / Q000032:analysis; D018534:Earth, Planet; D019419:Evolution, Planetary; D007053:Ice; D018543:Minor Planets; D009792:Oceans and Seas; D000069497:Origin of Life; D012623:Seawater; D013472:Sunlight
chemical_list: D000596:Amino Acids; D007053:Ice; D002245:Carbon Dioxide