Watch 25 Years of Arctic Sea Ice Melt in 64 Seconds
As climate change has driven up temperatures in the Arctic at about twice the rate of the rest of the world, the age and thickness of the northern ice cap have plummeted, as a new data visualization demonstrates.
The animation (an update of one released by United States government scientists in 2015) uses a combination of satellite, wind speed, and buoy data to show the week-to-week freezing, melting, and movement of Arctic sea ice between 1990 and 2015.
During the 1990s, about 20 percent of Arctic sea ice was five years old and older, comprising the whiter and lighter-colored areas of the ice cap. But by 2013, less than 5 percent of Arctic sea ice was five or more years old.
You can see that change happening in the animation: Around the mid-2000s, the darker areas, which indicate seasonal and younger multiyear ice, visibly grow.
The impacts from these changes are very real for wildlife and communities in the Arctic—and beyond. The retreat of the strong multiyear ice edge is why Arctic walruses have been coming to shore by the thousands for the past several summers, despite the lack of easy foraging and the risk of being trampled.
Some Alaskan villages, such as Kivalina, are falling into the sea because their coastlines are no longer protected by strong ice. And evidence is growing that low-ice years in the Arctic are changing weather patterns in North America, Europe, and Asia.
That’s consistent with seasonal and annual reports from the United States National Snow and Ice Data Center, which during the past decade has recorded several years with historic lows in sea ice. They include the record-setting low winter sea ice extent of 5.6 million square miles in March 2015, and the smallest sea ice minimum ever—1.3 million square miles—recorded in the summer of 2012.
Researchers also reported in March that some Arctic sea ice has thinned by around 65 percent, from 11 feet to four feet thick, since 1975.
“We’re seeing that there isn’t a lot of older ice in the Arctic anymore, compared to 1990 and that era,” said Mark Tschudi, the University of Colorado researcher who supplied the data for the new animation.
“Back then the ice pack was composed of a lot of older ice. That was probably a lot thicker and stronger ice pack that could survive the melt season fairly easily,” Tschudi said. “As we get into more recent times, we’re seeing an ice pack dominated by this first-year ice that hasn’t survived a melt season.”
The year-on-year loss of sea ice has created a negative feedback loop that is further diminishing the polar cap, he said, because open waters absorb about 94 percent of the sun’s warming radiation, creating warmer air and sea temperatures.
Snow-covered ice would reflect 80 to 90 percent of that heat back into space, and ice alone around 60 percent.
“It’s pretty evident that there’s a lot of warming going on in the Arctic,” Tschudi said.
Last year was the second-hottest on record in the U.S., and the 19th year in a row that the nation’s average temperature topped the 20th-century average. It was the hottest year ever recorded globally. The reason is the steady increase of carbon dioxide in the atmosphere, mostly owing to humans burning fossil fuels for energy.