Summer has arrived in the Arctic, and an early start to melting of the Greenland ice sheet is threatening the Arctic’s largest ice mass. In the past week, an area larger than the state of Texas was melting, covering more than 275,000 square miles. Normally, temperatures at Summit Station — so named because it lies atop the ice sheet at nearly 10,600 feetabove sea level — have an average high temperature of only 12 degrees Fahrenheit in June. But on June 12, the temperature neared 32 degrees.

Two images from this event have captured the attention of international media. The first was a graph produced at the National Snow and Ice Data Center with…