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Cited by 396Astro and Planetary SciencePaleontology and Stratigraphy of FossilsEarth Systems and Cosmic Evolution

The DOI matches its Crossref record; 89 of the 92 references it cites were found in a registry or an index.

The Early Faint Sun Paradox: Organic Shielding of Ultraviolet-Labile Greenhouse Gases

Sagan, Carl, Chyba, Christopher·1997·Science
DOI 10.1126/science.276.5316.1217
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Abstract

Atmospheric mixing ratios of ∼10 −5 ± 1 for ammonia on the early Earth would have been sufficient, through the resulting greenhouse warming, to counteract the temperature effects of the faint early sun. One argument against such model atmospheres has been the short time scale for ammonia photodissociation by solar ultraviolet light. Here it is shown that ultraviolet absorption by steady-state amounts of high-altitude organic solids produced from methane photolysis may have shielded ammonia sufficiently that ammonia resupply rates were able to maintain surface temperatures above freezing.

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Crossref · 10.1126/science.276.5316.1217

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89 of 89 references verified0 citation errors · 0 not checkable

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Cites

Show all 92 references

Research works printed but not linked: 15

  1. Wang W. C., Stoner P. H., ibid. 37, 545 (1980) .
  2. Eiler J. M., Mojzsis S. J., Arrhenius G., ibid. 386, 665 (1997).
  3. Karhu J., Epstein S., ibid. 50, 1745 (1986)].
  4. ]. On an Earth as warm as or warmer than today cloud feedback effects do not seem to be the answer [J. F. Kasting and D. H. Grinspoon in The Sun in Time C. P. Sonett M. S. Giampapa M. S. Matthews Eds. (Univ. of Arizona Press Tucson 1991) pp. 447–462].
  5. J. B. Pollack and C. Sagan in Near Earth Resources J. Lewis and M. Matthews Eds. (Univ. of Arizona Press Tucson 1993)
  6. J. M. Goldspiel thesis Cornell University (1994). An upper limit on the total amount of CO 2 ice in a martian polar cap can be set by the condition that it not liquefy at its base as a result of hydrostatic pressure load giving an upper limit of ∼60 mbar CO 2 [
  7. Sagan C., J. Geophys. Res. 78, 1250 (1973)].
  8. Khare B. N., Sagan C., Bandurski E. L., Nagy B., ibid. 199, 1199 (1978)].
  9. Sagan C., Thompson W. R., ibid. 59, 133 (1984).
  10. CH 4 is present at 0.1 to 1% of [H 2 O] in comets [M. J. Mumma P. R. Weissman S. A. Stern in Protostars and Planets III E. H. Levy and J. I. Lunine Eds. (Univ. of Arizona Tucson 1993) pp. 1177–1252]. For an impactor mass flux ∼5 × 10 14 g year −1 around 4 Ga (11) exogenous CH 4 supply provided <1% of the required flux.
  11. C. F. Chyba T. C. Owen W.-H. Ip in Hazards Due to Comets and Asteroids T. Gehrels Ed. (Univ. of Arizona Press Tucson 1994) pp. 9–58.
  12. C. Sagan B. N. Khare J. Lewis in Saturn T. Gehrels and M. S. Matthews Eds. (Univ. of Arizona Press Tucson 1984) pp. 788–807.
  13. Jenniskens P., Astron. Astrophys. 272, 465 (1993).
  14. Greenberg J. M., Hage J. I., ibid. 361, 260 (1990).
  15. Bussoletti E., Colangeli L., Borghesi A., Orofino V., Astron. Astrophys. Suppl. Ser. 70, 257 (1987).

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Metadata

Authors
Sagan, C., & Chyba, C.
Affiliations
University of Arizona (US)
ORCID
Venue
Science
Publisher
American Association for the Advancement of Science (AAAS)
Published
1997-05-23
Volume
276
Issue
5316
Pages
1217-1221
ISSN
  • 0036-8075 (ISSN-L)
  • 1095-9203
DOI
10.1126/science.276.5316.1217
OpenAlex
W1964099544
Cited by
396
References
92
Citations by year
2026: 7 · 2025: 10 · 2024: 12 · 2023: 11 · 2022: 8 · 2021: 9 · 2020: 18 · 2019: 5 · 2018: 14 · 2017: 14 · 2016: 11 · 2015: 7 · 2014: 16 · 2013: 25 · 2012: 17
FWCI
14.02
Type
journal article
Language
en
Open access
closed
Locations
  • Science (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Physical Sciences › Earth and Planetary Sciences › Space and Planetary Science › Astro and Planetary Science
  • Physical Sciences › Earth and Planetary Sciences › Paleontology › Paleontology and Stratigraphy of Fossils
  • Physical Sciences › Environmental Science › Global and Planetary Change › Earth Systems and Cosmic Evolution
Keywords
early Earth, ammonia, greenhouse gases, UV protection, organic solids, methane photolysis, ammonia photodissociation, atmospheric mixing ratios, surface temperature, early atmosphere
MeSH terms
Ammonia, Atmosphere, Carbon Dioxide, Methane, Models, Chemical, Photolysis, Ultraviolet Rays, Solar System, Greenhouse Effect, Earth, Planet, Evolution, Planetary

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