OTTAWA (Reuters) - Summer temperatures in the Arctic have risen at an incredible rate over the past three years and large patches of what should be ice are now open water, a British polar explorer said on Monday. Ben Saunders, forced by the warm weather to abandon an attempt to ski solo from northern Russia across the North Pole to Canada, said he had been amazed at how much of the ice had melted. "It's obvious to me that things are changing a lot and changing very quickly," a sunburned Saunders told Reuters less than two days after being rescued...