In the Arctic Ocean, it used to go like this: Sea ice expanded to the surrounding coastlines in the winter and melted back a bit in the summer. (Thus we often hear scientists discussing the region’s annual maximums and minimums of ice.) Multiyear ice forming to the west, northeast of Alaska and east of Russia, replaced older ice that spread farther to the east.
But as this new animation from the National Oceanic and Atmospheric Administration shows, since 1987 first-year ice (in darkest blue) has become common, while older, multiyear ice (paler blue and gray to white) has decreased sharply. From the mid-2000s on, older ice has almost vanished from the western side of the Arctic Ocean, making its final stand along the Canadian Arctic Archipelago.
The reason, of course, is climate change. The Arctic is warming at a faster rate than the rest of the world, creating profound changes in the environment. Overall, Arctic sea ice has decreased by around 14 percent since the 1970s, hitting a record low in September 2012.
Historically most of the Arctic ice cap was made of multiyear ice fringed by thinner first-year ice. The ice thickened as it endured from year to year, creating a strong platform for both animals, such as polar bears, and native hunters to use for resting and finding prey. The older ice protected the coastlines from erosion. Thicker ice also likely reflected more of the sun’s heat back into space, helping to keep temperatures relatively cool in the northern hemisphere.
Now rising temperatures in the western Arctic Ocean are dampening the formation of long-term sea ice. At the same time, the ocean’s loop current continues to transport sea ice into the North Atlantic east of Greenland.
“The best scientists in the world are all telling us that our activities are changing the climate,” President Obama said in his State of the Union speech Tuesday night. “I will not let this Congress endanger the health of our children by turning back the clock on our efforts.”
But it may well be too little, too late to reverse the profound changes already transforming the Arctic.