A carbon dioxide molecule has two covalent bond and one coordinate bond (which is itself also a special type of covalent bonds), and altogether three bonds.
It is impossible to give a figure but it will be a lot lower as the polarity makes the molecules bond more tightly together. Remembering that H2S is a gas at room temperature (it is polar but not as much as water), I would imagine that water would be too but its boiling point would be even lower than H2S. However there are other factors affecting boiling point other than polarity.
Covalent bonds occur at a potential energy minimum  As two atoms approach one another, the potential energy decreases. When the potential energy is at its minimum value, the two-atom combination is most stable because lower energy means greater stability.