The Bering Sea, where the boats of Deadliest Catch do their work, is not known for toasty warm weather. But still, some years are colder than others. The last two winters have been particularly chilly — and they've been huge years for ice. The last time the ice came this far south was in the early 1970s, when scientists first used satellites to monitor the ice.
Image Credit: DCL Photos by Chris Linder, Woods Hole Oceanographic Institution
Q: So where does all that ice come from?
A: Sea ice is frozen seawater. It's different from icebergs, which break off from glaciers or ice shelves. In the Bering Sea, the ice mostly forms in the north, starting in November or December, and blows south, toward the fishing and crabbing grounds.
As the leading edge of the ice reaches warmer water, it melts. But the melting ice cools the water and the next batch of south-moving ice doesn't melt as fast. Eventually, as ice keeps blowing south, the water is cold enough for the ice to stay frozen, and the ice spreads across the sea.
Image Credit: DCL Photos by Chris Linder, Woods Hole Oceanographic Institution
Q: Shouldn't the Bering Sea be heating up?
A: The average temperature of the Earth is going up, but that doesn't mean every spot on the globe gets warmer every year.
"There is some global warming effect in the Bering Sea, but it's still dominated by the large swings from warm to cold and back to warm again," says Jim Overland, an oceanographer at the National Oceanic and Atmospheric Administration in Seattle.
As the Earth's atmosphere continues to warm, the Bering Sea is expected to follow suit.
Image Credit: DCL Photos by Chris Linder, Woods Hole Oceanographic Institution
Q: Does the ice affect the animals that live in the Bering Sea?
A: Yes. Four species of seals have their pups on the sea ice in the spring, so the moms need the ice to be there when they're ready to give birth. Walruses haul out on the ice between dives to the bottom, where they get clams and other tasty food.
The critters in the Bering Sea that humans like to eat depend on ice, too. When the ice breaks up and melts in the spring, sun hits the open water for the first time in months. Tiny phytoplankton start doing photosynthesis; they get eaten by tiny animals, which are eaten by bigger animals, and so on up the food chain to crabs and fish.
Image Credit: DCL Photos by Chris Linder, Woods Hole Oceanographic Institution
Q: So what happens to the ecosystem when the climate warms?
A: Dozens of scientists are working on a six-year, $52 million study to answer that question: What happens to the Bering Sea ecosystem, from krill to walruses to humans, when there is less ice?
"The one thing you can say is, it's going to change," says Phyllis Stabeno, an oceanographer at the National Oceanic and Atmospheric Administration in Seattle, who is part of the study.
Image Credit: DCL Photos by Chris Linder, Woods Hole Oceanographic Institution
