The archaeological record is riddled with as much evidence of much higher sea levels with warmer climates as is it lower ones during ice ages.
One of the two is heading our way, we just have to wait for the earth to "decide" which way it's going to swing. Either way we're in for one hell of a ride.
Odds are it's likely that we will not be around to see it but the records also show that when it does happen, it's a relatively quick process.