Arctic sea ice shrank to its summer minimum — tying 2007 for the second-lowest level on record — last week, according to data released Thursday by the National Snow and Ice Data Center and NASA.
Sea ice affects Arctic communities and wildlife such as polar bears and walruses and also helps regulate the planet’s temperature by influencing the circulation of the atmosphere and ocean.
Sea ice extent was measured at 1.6 million square miles on Sept. 10. That's 911,000 square miles below the average.
"It was a stormy, cloudy and fairly cool summer,” said ice center director Mark Serreze. “Historically, such weather conditions slow down the summer ice loss, but we still got down to essentially a tie for second lowest in the satellite record."
September is the month when Arctic ice reaches its lowest "extent" of the year, toward the end of the Northern Hemisphere's summer.
Sea ice is frozen ocean water that melts each summer, then refreezes each winter. The refreezing process has now begun, the data center said. Arctic sea ice reaches its largest area in March each year.
The this year ranks behind only 2012, when the lowest level on record was measured. Arctic sea ice has been measured since 1979, and the 10 smallest areas since then occurred in the past decade.
The amount of summer sea ice in the Arctic has been steadily shrinking over the past few decades, due to man-made global warming, according to the National Oceanic and Atmospheric Administration.
“It is difficult to predict how Arctic ecosystems will respond to decreasing sea ice extent, but we are seeing more species moving in to take advantage of warming Arctic waters, and specialized Arctic species such as polar bears showing signs of stress in some regions,” said Melanie Lancaster of the World Wildlife Fund. “Conservation action to preserve the Arctic is urgently needed to keep up with these rapid changes."
Globally, even though Antarctic sea ice has gotten larger, sea ice has declined overall.
“It really suggests that in the next few years, with more typical warmer conditions, we will see some very dramatic further losses," said Ted Scambos, NSIDC lead scientist.