3D climate model and the inner HZ edge

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3D climate model and the inner HZ edge

Post by Lazarus on 12th December 2013, 6:00 pm

Nature (paywalled): Increased insolation threshold for runaway greenhouse processes on Earth-like planets

Runaway greenhouse estimated to be at 0.95 AU, as opposed to 0.97 AU from Kopparapu et al. (2013)

Unfortunately this is paywalled, not sure if there are implications for the water-loss limit also (0.99 AU in Kopparapu et al. 2013).

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Re: 3D climate model and the inner HZ edge

Post by Sirius_Alpha on 12th December 2013, 9:21 pm


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Re: 3D climate model and the inner HZ edge

Post by Lazarus on 13th December 2013, 1:25 pm

Thanks for the link - looks like it does address the water-loss question:
However, the question of whether or not the warming-induced increase of the stratospheric temperature and humidity could cause the loss of the oceans by atmospheric escape before the runaway greenhouse is triggered, as suggested by some 1D studies4,6, is still subject to debate. Our simulations tend to invalidate this scenario. This is due to both non-gray radiative effects14,21,22 (see Methods) and unsaturated regions that flatten the thermal profile in the troposphere. As a result, stratospheric temperature are much colder than anticipated and stratospheric humidity cannot reach the threshold needed for efficient water photodissociation and hydrogen escape to space (see Fig. 3).
So perhaps the water loss limit is not such an issue?

Also, by coincidence their runaway greenhouse limit is at the same distance as the Kasting (1993) water loss limit. Smile
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Re: 3D climate model and the inner HZ edge

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