A New Idea on the Faint Young Sun Problem

Astronomer (and old usenet sci.env denizen) Steinn Sigurðsson has spotted a paper that suggests a resolution to the Faint Young Sun problem.

The standard solar model predicts a young Sun which was too faint to sustain liquid water on the Earth, unless there was an extreme greenhouse effect at the time, which seems to contradict the geochemical record. It seems to be almost impossible to get liquid water on Mars under the standard solar model with any plausible early Mars atmosphere.

It’s here.

And by the way, Steinn still owes us an update on his opinions on climate change, and possibly a reminiscence on the late John McCarthy while he is at it.



  1. The early greenhouse problem is also discussed in the great (if not magnificient) book of Tim Lenton & Andrew Watson, Revolutions that made the Earth, §10.7.1.

    One way out would be a more efficient greenhouse due to the "pressure broadening" effect: Perhaps there was 2x - 3x more nitrogen in the early atmosphere, thus higher pressure, thus broadening the absorption lines of greenhouse gases.

    C. Goldblatt et al., Nitrogen-enhanced greenhouse warming on early Earth. Nature Geoscience 2, 891 (2009)

    Now what about nitrogen on early Mars?

  2. The Earth could well have had a lower albedo combined with a much denser, greenhouse atmosphere and a high degree of volcanism. My question is, how widespread is the evidence for liquid oceans / life from the Hadean to the Precambrian? We DO have evidence for several "Snowball Earth" events where runaway cooling allowed ice to form at the equator.

    What if snowball events were the norm punctuated by brief supergreenhouse periods that were caused by the breakdown of the water cycle? I guess the slow but steady climb in atmospheric O2 that has been measured in rocks from the period might preclude this from happening, but it's a possibility. Another possibility is that the Earth migrated out further from the Sun during this period. Finally, how solid is the evidence for growing solar luminosity as far as magnitude and rate of change over its lifetime?

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