Fueled by unusual warmth at the top of the world, Arctic sea ice shrank to its second-lowest level on record last week, scientists announced Monday.
“It's been a crazy year up north, with sea ice at a near-record low, 100-degree (Fahrenheit) heat waves in Siberia and massive forest fires,” said Mark Serreze, director of the National Snow and Ice Data Center, which made the announcement, along with NASA.
“The year 2020 will stand as an exclamation point on the downward trend in Arctic sea ice extent," he said. "We are headed toward a seasonally ice-free Arctic Ocean, and this year is another nail in the coffin.”
Sea ice is frozen ocean water that melts each summer and then refreezes each winter. It affects Arctic communities and wildlife such as polar bears and walruses, and it helps regulate the planet’s temperature by influencing the circulation of the atmosphere and ocean.
Arctic sea ice typically reaches its smallest extent in September and largest in March.
The minimum was reached on Sept. 15 and measured 1.44 million square miles. This is about 958,000 square miles below average, according to a statement from NASA.
This appears to be the lowest extent of the year, the National Snow and Ice Data Center said. In response to the setting sun and falling temperatures, ice extent will begin increasing through autumn and winter. However, a shift in wind patterns or a period of late-season melt could still push the ice extent lower.
This year ranks behind only 2012, when the lowest level on record was measured. Arctic sea ice has been measured since 1979.
The amount of summer sea ice in the Arctic has been steadily shrinking over the past few decades because of man-made global warming, according to the National Oceanic and Atmospheric Administration and NASA.
A Siberian heat wave in the spring began this year’s Arctic sea ice melt season early, and with Arctic temperatures being 14 to 18 degrees Fahrenheit higher than average, the ice extent kept declining.
"It was just really warm in the Arctic this year, and the melt seasons have been starting earlier and earlier,” said Nathan Kurtz, a sea ice scientist at NASA’s Goddard Space Flight Center. “The earlier the melt season starts, the more ice you generally lose.”
The 14 lowest extents on record have all occurred in the past 14 years.
It's official. 2020's #Arctic sea ice minimum was the 2nd lowest ever observed. The long-term trend is clear 📉
+ Press release (@NSIDC): https://t.co/fBUTSWE0OD
+ Extremes from this summer 👇 https://t.co/7p5Y7YZp03 pic.twitter.com/po1M2DSIJa
— Zack Labe (@ZLabe) September 21, 2020
“Sea ice keeps our planet cooler, so when we lose ice, the entire world warms," said Cecilia Bitz, a professor of atmospheric sciences at the University of Washington. "Arctic sea ice is essential for the survival of polar bears and seals, and humans rely on it, too – northern communities use it for travel and for hunting, and sea ice damps ocean waves, protecting coastal communities from storm-induced damage."
Bitz said that Arctic sea ice is an asset for our planet, but it is disappearing rapidly. "In my lifetime, the sea ice at the end of summer has decreased by 50%, and now we’ve found that late summers may be ice-free in a few decades.
"When it is gone, we'll have lost a sea ice area about equal to the area of the lower 48 states of the U.S.,” she said.
Serreze said the second-lowest extent of sea ice on record is just one of many signs of a warming climate in the north, pointing to the Siberian heat waves, forest fires, higher-than-average temperatures over the Central Arctic and the thawing permafrost that led to a Russian fuel spill.
This article originally appeared on USA TODAY: Arctic sea ice, global warming: Ice shrinks to second-lowest level