Carbon dioxide feedback on ocean planets

Kitzmann et al. "The unstable CO₂ feedback cycle on ocean planets"
http://arxiv.org/abs/1507.01727

Clue's in the title: the carbon dioxide cycle on ocean planets, where carbon dioxide is removed from the atmosphere by dissolving into the ocean, is unstable: a cooler ocean is more able to dissolve carbon dioxide, thus removing a greenhouse gas from the atmosphere and tending towards runaway cooling, while a hotter ocean is less able to dissolve carbon dioxide and therefore tends to push conditions towards runaway greenhouse. Combined with the ice-albedo feedback it seems that the liquid water zone for ocean planets is much narrower than for terrestrial planets on which a silicate-carbonate cycle can operate.

Maybe there is a possible negative feedback for carbon dioxide after all...

Levi, Sasselov & Podolak "The Abundance of Atmospheric CO₂ in Ocean Exoplanets: A Novel CO₂ Deposition Mechanism"
https://arxiv.org/abs/1609.08185