The early faint sun paradox: Organic shielding of ultraviolet-labile greenhouse gases

被引:258
作者
Sagan, C
Chyba, C
机构
[1] CORNELL UNIV,PLANETARY STUDIES LAB,ITHACA,NY 14853
[2] UNIV ARIZONA,DEPT PLANETARY SCI,TUCSON,AZ 85721
关键词
D O I
10.1126/science.276.5316.1217
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
Atmospheric mixing ratios of similar to 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 ultraviotet absorption by steady-state amounts of high-attitude organic solids produced from methane photolysis may have shielded ammonia sufficiently that ammonia resupply rates were able to maintain surface temperatures above freezing.
引用
收藏
页码:1217 / 1221
页数:5
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