Arctic sea ice hit its lowest recorded level on Sunday and could fall even lower before the end of the year, U.S. climate researchers said this week. Using satellite measurements, scientists from the National Snow and Ice Data Center confirmed that a mere 1.58 million square miles of the Arctic is covered at least 15 percent by sea ice, breaking the previous low, recorded in 2007. And the melt isn't over yet: Ice at the planet's northern extreme typically continues melting through the summer, not reaching its annual minimum until September. Besides providing habitat for ice-dwelling animals like polar bears and walruses, light-colored sea ice helps keep the planet cool by reflecting solar energy back into space. The NSIDC said this year's melt has been significantly faster than normal.