NASA analysis of satellite data has suggested that 2015 Arctic sea ice minimum extent was the fourth lowest on record since the start of observations from space. As per the analysis by NASA and the NASA-supported National Snow and Ice Data Center (NSIDC) at the University of Colorado at Boulder, the annual minimum extent was 1.70 million square miles on September 11. This year's minimum was 699,000 square miles lower as compared to the 1981-2010 average.

Arctic sea ice cover is made of frozen seawater floating on top of the ocean. It helps in regulating Earth’s temperature by reflecting solar energy back to space. With the seasons, the sea ice cap grows and shrinks cyclically. Since the late 1970s, its minimum summertime extent, which occurs at the end of the melt season, has been decreasing due to warming temperatures.

Walt Meier, a sea ice scientist with NASA's Goddard Space Flight Center in Greenbelt, Maryland, said, “This year is the fourth lowest, and yet we haven't seen any major weather event or persistent weather pattern in the Arctic this summer that helped push the extent lower as often happens”. Walt Meier said it was a bit warmer in some areas as compared to previous year, but it was cooler in other places also.

In contrast, the lowest year on record, 2012, faced a strong August cyclone that fractured the ice cover and accelerated its decline. Since 1996, the sea ice decline has accelerated.