Guardian: One of the world’s leading ice experts has predicted the final collapse of Arctic sea ice in summer months within four years. In what he calls a “global disaster” now unfolding in northern latitudes as the sea area that freezes and melts each year shrinks to its lowest extent ever recorded, Prof Peter Wadhams of Cambridge University calls for “urgent” consideration of new ideas to reduce global temperatures. In an email to the Guardian he says: “Climate change is no longer something we can aim…