Seasonal ice in the Arctic used to melt and freeze in a predictable cycle. However, as climate change accelerates, much of that summertime ice no longer returns at all. The Arctic now spans less than half the area it did in the early 1980s. A 400,000-square-mile region north of Greenland and the Canadian Arctic Archipelago known as the Last Ice Area was previously seen as resistent to much of global warming's effects, but new estimates show this area is under serious threat.
The Last Ice Area has the thickest, most resilient year-round ice that persists year-round. According to both pessimistic and optimistic scenarios described in a recent study, the important region will be alarmingly thin by 2050. Now, scientists are racing to understand what this would mean for arctic animals that rely on it for survival.
Though Last Ice Area will likely be the last ice remaining in the Arctic as global warming persists, it's not clear how long the ice will survive. Pessimistic scenarios show that summertime sea ice will be gone entirely by 2100. The study was published in September in the journal Earth's Future.
"Unfortunately, this is a massive experiment we're doing," said study co-author Robert Newton, a climate research scientist at Columbia University, in a statement. "If the year-round ice goes away, entire ice-dependent ecosystems will collapse, and something new will begin."
In September, a computer simulator predicted that the Last Ice Area could retain summer sea ice if the planet doesn't warm more than 2 degrees Celsius above preindustrial levels, reports Freda Kreier for Science News. However, a recent United Nations report spells trouble. Under current pledges to reduce emissions, temperatures will increase by 2.7 degrees Celsius by 2100. With such a steep increase, summer sea ice in the Arctic will disappear completely.
The Last Ice Area is a sensitive ecosystem that is crucial for Arctic life and may be the only place where animals will find sanctuary in the dire face of climate change. When the Northern Hemisphere returns to winter, the Arctic Ocean refreezes and ice in the Last Ice Area grows to a meter thick. When some ice melts summer, winds and currents carry floating ice from continental shelves off Siberia to the open waters, reports Kelly Kizer Whitt for Earth Sky. These flows of ice pile up and form ten-meter-high ridges that can remain frozen for more than a decade in the Last Ice Area. Canada's islands prevent the ice from drifting further into the Atlantic Ocean, per Science News.
Underneath the ice in the Last Ice Area, a rich ecosystem generates the region's food chain. Plankton and single-celled algae eventually form thick mats at the edges and bottoms of the ice sheets, forming the foundation of the Arctic's food cycle. Algae feeds fish, seals eat fish, and polar bears hunt seals, reports Earth Sky. Thick iceburgs also provide shelter for polar bears and seals.
However, a warming climate means newly formed ice is thinner and melts faster each year as summer heat lasts longer. Overall, less ice drifts northward to eventually accumulate in the Last Ice Area. But plankton can't survive without the ice, and without plankton, the food chain collapses and other animals will go along with it. Researchers hope that the Last Ice Area and its thin summer ice will be enough to provide the final floating sanctuary for animals like polar bears and other species as they ride out global warming.
But many scientists are optimistic that if carbon emissions are reduced globally in the 21st century, the region will survive until temperatures drop again and the ice can regrow, Earth Sky reports. However, the area must also be protected against mining and other developments to protect the area, Science News reports.
"The tragedy would be if we had an area where these animals could survive this bottleneck, but they don't because it's been developed commercially," Newton explains to Science News.