He promised that there would be no other flood? I'm sure the folks in Louisiana would be glad to know that their homes didn't actually flood.

If you want to get Biblical, God promised that He'd never again flood the entire world. He can still flood portions of the world without breaking his vow. So if Global Warming permanently floods every coastal city around the world, the "Great Flood Promise" won't have any effect on this. (I'm side stepping the "A Biblical Promise won't stop real life things from happening" argument, of course.)