“Greenland” ranks well above average when it comes to disaster movies. Screenwriter Chris Sparling takes the traditional end of the world blueprint and inserts some really nice surprises and twists, making this formulaic action flick seem not as much so. John (Gerard Butler) is in a race against time to save his wife (Morena Baccarin) and son (Roger Dale Floyd) from an alien killer comet that is hurtling towards Earth. The impact of the big one is expected in less than 24 hours, and there seems to be no hope for any survivors. While at the grocery store, John gets a terrifying message from ...