Still, I think 5 year is one of the more pessimistic estimates. I'm betting closer to ten before the ice caps are entirely gone.
It's a feedback loop. Snow and Ice is white; it reflects between 40 and 80% of the light that shines on it. Water is blue; it reflects only about 5 to 10%. So as ice coverage gets smaller the speed at which the arctic heats up gets faster.
Because of that and the break down of the polar vortex (it's why the winters have been so hard lately in the US and Europe, the arctic winters have been very mild) I feel that a pessimistic view is justified, we've reached a tipping point in all likelihood. We've got two negative feedbacks on Arctic Temperatures going.