According to the cinematic gem "The Day After Tomorrow," global warming is going to hit us smack upside the head and at lightning speed. Forget the fact that geological records show that even the fastest-descending ice ages still take about a decade to consume the world ... not a matter of days.
But even worse than this fundamentally basic climatological blip is what occurs as the ice age descends. (This descent, we should note, does not solely punish those who live in already frosty climes. It is an equal opportunity meteorological avenger.) More pertinent to the plot is when a cell of tornadoes sashays down the red carpet in L.A. and a tsunami roundhouses Manhattan to the face.
The temperature, all the while, is going down fast. Like 10 degrees a second fast. Once it hits 130 degrees below zero Fahrenheit (minus90 degrees Celsius), you know stuff's about to get real. And by real, we mean even more ludicrous. Because that's when a flooded Manhattan freezes over, and the water doesn't do something water definitely does when it freezes – expand to crush all the buildings and the people cowering inside. (Sure, other liquids get smaller when they freeze, but water expands. Just look at what happens to soft drinks when the fridge gets too cold.)