Brief Communications Arising | Published:

Faint young Sun paradox remains

Nature volume 474, page E1 (02 June 2011) | Download Citation


Arising from M. T. Rosing, D. K. Bird, N. H. Sleep & C. J. Bjerrum, Nature 464, 744–747 (2010)10.1038/nature08955

The Sun was fainter when the Earth was young, but the climate was generally at least as warm as today; this is known as the ‘faint young Sun paradox’. Rosing et al.1 claim that the paradox can be resolved by making the early Earth’s clouds and surface less reflective. We show that, even with the strongest plausible assumptions, reducing cloud and surface albedos falls short by a factor of two of resolving the paradox. A temperate Archean climate cannot be reconciled with the low level of CO2 suggested by Rosing et al.1; a stronger greenhouse effect is needed.

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  1. *Space Science and Astrobiology Division, NASA Ames Research Center, MS 245-3, Moffett Field, California 94035, USA

    • Colin Goldblatt
    •  & Kevin J. Zahnle


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C.G. and K.J.Z. discussed the article to which this note responds. C.G. performed all model runs and quantitative analysis. C.G. and K.J.Z. both contributed qualitative analysis and both contributed to writing the paper.

Competing interests

Competing financial interests: declared none.

Corresponding author

Correspondence to Colin Goldblatt.

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