Global Warming

Mayhem as sea ice melts in heating world - Bering Strait

In the Bering Strait region, where a narrow passage separates Alaska from Russia and links the Arctic Ocean to the Pacific, the sea ice is long gone and mayhem has taken hold in the marine environment.

The most striking signs are on the shorelines, which have been littered with dead animals ranging from tiny shellfish to giant whales.

The toll of discovered dead animals as of mid-July: 137 ice-dependent seals and five gray whales, according to the National Oceanic and Atmospheric Administration (NOAA); dozens of walruses, piles of bird carcasses — marking what has become the latest in five consecutive years of bird die-offs in the region; carcasses of salmon that never got the chance to spawn clogging rivers and streams; and in some spots, stretches of dead blue mussels and krill have coated beaches.

Sometimes animals are found alive, but only barely so. A walrus found in June near Solomon, a village 30 miles east of Nome, was so thin that its ribs were visible and so weak its head was down on the ground, according to a local report. “It was having trouble keeping its head out of the mud,” said the report filed with the Local Environmental Observer network operated by the Alaska Native Tribal Health Consortium.

Extreme warmth that, this summer, brought air temperatures in places to the high 80s and even low 90s Fahrenheit (or into the 30s Celsius) and cooked marine waters.

Freeze-up that used to come in fall is now delayed to mid-winter and the ice that forms is thin. That thinner ice melts earlier, exposing open waters that absorb more of the sun’s heat. That means water temperatures soar, freeze-up is again delayed, the late-forming winter ice is again thin, melt is early, and so on.

When there is little or no ice, seals and walruses cannot find platforms to rest in between food-foraging dives and during key life events like birth and nursing of young. More light penetrates the water, boosting phytoplankton blooms and upsetting a prior balance, benefitting fish and pelagic species in the upper reaches of the ocean water but reducing the amount of nutrition that drifts down to the deep-dwelling benthic species like tiny amphipods, clams, crabs and snails that are crucial to the marine-mammal food web.

The absence of a winter freeze also means lack of the usual “cold pool” of ultra-salty, super-chilled water that normally serves as an underwater barrier separating the high-fat, nutrition-dense species in the northern Bering Sea from the lower-fat species that live in the southern part of the sea.

There is another possible heat-related explanation for the die-offs: lack of the high-quality, high-fat food in the environment. As water temperatures rise, the lower-fat species more typical of the southern Bering Sea are moving north, taking over the higher-fat northern species’ territory.

Among the newcomers is Pacific cod, a staple of people’s diets for millennia in southern Alaska and marine predators so voracious they are known to eat seabirds. To the south, in the heated-up Gulf of Alaska, cod have become scarce, a severe blow to commercial fishermen and fishing-dependent communities; harvest quotas were slashed so deeply that the state sought a fisheries disaster declaration from the federal government. Now it appears that cod populations have swum north, swarming Norton Sound, a waterbody famous for its harvests of succulent king crab.

The wildlife in the region are unable to adequately deal with changes and interruptions in their traditional food chains and poisoning from the toxins released by increasingly prevalent algal blooms.