The water off the coast of northwest Greenland is a glass-like calm, but the puddles accumulating on the region's icebergs are a sign that a transformation is underway higher on the ice sheet.

Several days of unusually warm weather in northern Greenland have triggered rapid melting, made visible by the rivers of meltwater rushing into the ocean. Temperatures have been running around 60 degrees Fahrenheit -- 10 degrees warmer than normal for this time of year, scientists told CNN. The amount of ice that melted in Greenland between July 15 and 17 alone -- 6 billion tons of water per day -- would be enough to fill 7.2 million Olympic-sized swimming pools, according to data from the US National Snow and Ice Data Center.