sentences:  The higher surface gravity would lead to a thicker atmosphere, increased surface erosion and hence a flatter topography.The end result could be an "archipelago planet" of shallow oceans dotted with island chains ideally suited for biodiversity.A more massive planet of two Earth masses would also retain more heat within its interior from its initial formation much longer, sustaining plate tectonics (which is vital for regulating the carbon cycle and hence the climate) for longer.