First, we are not talking about the end of the world! A flood, nuclear fall out, asteroids, global warming...none of these things will end THE WORLD. We are talking the end of humanity. Big difference.
Second, the only accurate predictions of the end of humanity will be immediately before everyone dies.
Oh, and a side note. Because we are talking about the end of humanity...people really do fear the wrong things. We are far more likley to die of an antibiotic resistant strain of disease then we are the polar Ice Caps melting. And even then it would be like when the bubonic plaque hit. Around 10% of people would have a natural resistence, 20%-30% would not get infected and the rest would die.
See, no worries guys!