Are we talking about the polar caps melting or an ice age? I'm confused.

Polar caps melting is no big deal. Some cities might get wet, but I don't think it's that bad. The ocean is huge, and I don't think there's so much ice that it would raise the sea level more than a few meters. If it's actually that life threatening, I would be geniunely surprised.

Ice age is survivable thanks to our knowledge of stuff. Granted rules of overpopulation (population/food source ratio) would force lots of us to die, but so what?