All Figures

	Figure 1: Earth system box model. The arrows indicate the different forcing and feedback mechanisms. The bold arrows indicate negative feedback operating towards climate stabilization.
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In the text

	Figure 2: Geophysical forcing ratios (GFR) for a planet with (solid line), (dotted line) and (dash-dotted line) for a relative continental area of 0.3.
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In the text

Figure 3: The pHZ of Gl 581 for a super-Earth ( ) with a relative continental area varied from 0.1 to 0.9 and a fixed stellar luminosity of  a)  , b)  , and  c)  as a function of planetary age. The light colours correspond to a maximum CO2 pressure of 5 bar, whereas the dark colours correspond to 10 bar. For comparison, the positions of Venus, Earth and Mars are shown scaled to the luminosity of Gl 581. The light grey shaded area denotes the HZ calculated from Eq. (1), while the dark shaded area corresponds to an extended outer limit following Mischna et al. (2000). The vertical bar at 2 Gyr denotes the range of distances due to the (possibly) eccentric orbit. The area below the solid black curve is affected by tidal locking.

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In the text

Figure 4: The pHZ of Gl 581 for a super-Earth ( ) with a relative continental area varied from 0.1 to 0.9 and a fixed stellar luminosity of  a)  , b)  , and  c)  as a function of planetary age. The light colours correspond to a maximum CO2 pressure of 5 bar, whereas the dark colours correspond to 10 bar. For comparison, the positions of Venus, Earth and Mars are shown scaled to the luminosity of Gl 581. The light grey shaded area denotes the HZ calculated from Eq. (1), while the dark shaded area corresponds to an extended outer limit following Mischna et al. (2000). The vertical bar at 2 Gyr denotes the range of distances due to the (possibly) eccentric orbit. The area below the solid black curve is affected by tidal locking.

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In the text