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    • Guest Nicole
      By Guest Nicole
      The changes are already visible in the region, which has had largely ice-free summers since 2011

      The Arctic is undergoing an astonishingly rapid transition as climate change overwhelms the region.
      New research sheds light on the latest example of the changes afoot, showing that parts of the Arctic Ocean are becoming more like the Atlantic. Warm waters are streaming into the ocean north of Scandinavia and Russia, altering ocean productivity and chemistry. That’s making sea ice recede and kickstarting a feedback loop that could make summer ice a thing of the past.
      “2015 was a really anomalous year when we had problems finding a suitable ice flow to launch our drifting buoys,”Igor Polyakov, an oceanographer at the University of Alaska who led the new study, said. “(There was) nothing like that in the past, and it became a motivation to our analysis: why was ice in 2015 so rotten? What drives this huge change?”
      The findings, published in Science on Thursday, show that while warming air has a role to play, processes are playing out in the ocean itself that are fundamentally altering the region.
      Those changes will have impacts on the people, plants and animals that call the Arctic home. They could also create more geopolitical tension as resources previously locked under ice become available and shipping lanes open up.
      In the east Arctic Ocean, the shift is manifesting itself in changing the layers of the ocean. There’s a cap of cold, less salty water that covers the eastern portion of the Arctic Ocean. Underneath it sits a pool of warm, salty Atlantic water that until recently hasn’t been able to find a way to surface. That stratification of layers has kept ice relatively safe from its warm grip.
      The ocean has become gradually less stratified since the 1970s. Using data from buoys and satellites, Polyakov and his colleagues have found a more marked shift over the past decade and a half. Since 2002, the difference in water temperatures between the layers has dropped by about 2°F.
      In winter from 2013-2015, the cap separating the deep water and surface water disappeared completely in some locations, allowing the warm Atlantic waters to reach the surface and cut further into sea ice pack. At the same time, warm air has further reduced sea ice, which is allowing still more mixing of the ocean layers.
      The result is a feedback loop that is essentially turning roughly a third of the eastern Arctic Ocean into something resembling the ice-free Atlantic Ocean.
      “Rapid changes in the eastern Arctic Ocean, which allow more heat from the ocean interior to reach the bottom of sea ice, are making it more sensitive to climate changes,” Polyakov said. “This is a big step toward the Arctic with seasonal sea-ice cover.”
      The changes are already apparent in the region, which has largely been ice-free during the summer since 2011. The sea ice winter maximum, which has set a record low for three years running, has been largely driven by a lack of ice in the eastern Arctic.
      Polyakov said he’s seen the rapid changes in ice firsthand. When they first put buoys in the eastern Arctic in 2002, researchers had to reach the sites on heavy icebreakers.
      “Now we can reach them using an ice class ship,” he said. Ice class ships are not necessarily as reinforced as icebreakers.
      The sea ice changes are having profound impacts outside of researchers’ ability to access more remote sites. Other research published earlier this week in Science Advances shows that thinning sea ice is allowing phytoplankton to bloom across the region.
      Phytoplankton are tiny plants, and like your average potted plant, they need sunlight to bloom. Sea ice has been thick enough to prevent that from happening until very recently. The new findings show that over the past decade, up to 30 percent of the Arctic has become primed for summer blooms.
      “Both of our results show the Arctic becoming a very different place than it has been in the past,” Christopher Hovart, an oceanographer at Harvard who led the plankton study, said. “Water pathways are changing, the ecology is changing, all driven by the declining sea ice field.”
      This article is reproduced with permission from Climate Central. The article was first published on April 6, 2017.

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    • Guest Nicole
      By Guest Nicole
      In September 2009, after a summer of warm weather and dwindling ice, a young polar bear slipped into the frigid waters of the Beaufort Sea and began to swim.
      She didn't stop for food or rest until nine days later, when she finally encountered a slab of sea ice large enough to sustain her. The journey was some 250 miles.
      That female polar bear was one of more than 100 monitored by biologistAndrew Derocher, a researcher at the University of Alberta who spent six years tracking bears in the waters off the northern coasts of Alaska and Canada. He found that, as sea ice in those areas fractured and melted away, the bears were making longer and longer swims across the open ocean — journeys that taxed their already limited resources and proved perilous to vulnerable cubs.
      "Ice is changing so quickly that we’re finding the bears are getting caught in places where they’re finally coming to the realization, 'I just can’t stay here,' " Derocher said in a phone interview. "... These kinds of long-distance swims are not what they evolved to undergo." 
      The results of Derocher's study, published in the most recent issue of the journal Ecography, show a dramatic increase in the number of polar bears paddling across vast expanses of ocean to find suitable ice to stand on. In 2004, just a quarter of the bears monitored performed a long-distance swim (defined as more than 50 kilometers, or about 31 miles). By 2012, that proportion had ballooned to 69 percent.
      The number of bears making such a swim was directly proportional to the loss of sea ice in the area, Derocher said.
      These journeys are hard on polar bears. Though they're good swimmers, they're not adapted to long trips and can only paddle about 2 kilometers an hour. A 30-mile journey to find new ice takes an entire day, during which the bears can't eat or rest. Adult bears are likely to lose weight, and their cubs tend to get hypothermic. In 2009, a mother bear who swam for nine days straight off the coast of Alaska (who was not part of Derocher's study) lost 22 percent of her body weight, biologists with the U.S. Geological Survey reported. Her year-old cub died during the journey.
      "With cubs, if they have to undergo a long distance swim, it's basically a death sentence," Derocher said.
      Mothers with cubs were much less likely to swim, he found. Instead, "they will walk for hundreds of kilometers to keep their cubs out of water."
      In part because of the difficulty of monitoring bears (collars can fall off or malfunction, bears seem to drop off the map), the amount of data Derocher and his colleagues collected varied from year to year. But the trend is pretty clear, Derocher said. In the 1980s, when he first began studying polar bears, it would have been unheard of for any bears to make a long distance swim, let alone dozens. In those days there was no need — the Beaufort Sea and Hudson Bay (the two areas covered by the study) were clogged with ice even in the height of summer.
      That's changed now, especially in the Beaufort Sea above Alaska and the Yukon, which has seen an especially large decline in sea ice compared with the Hudson Bay. Satellite images taken earlier this month show that the ice there is already beginning to break up. That's bad news during prime hunting season for polar bears, which rely on sea ice as a platform from which to dive for seals and other prey.
      "None of this is what I would call a smoking gun as to what is happening with polar bear abundance, but the signs are all pointing in the same direction," Derocher said. "We're seeing bears with lower body fat, fewer cubs, changing hunting behavior."
      Pair that with a 2014 study that found that the polar bear population in the southern Beaufort Sea dropped between 25 and 50 percent from 2001 to 2010, and the picture becomes pretty clear.
      "The Beaufort population is one of the ones that will more than likely be extirpated probably by mid-century," Derocher said.
      The best-case scenario is that these bears will travel south and find a way to hunt on land during the summers, the way some of their Hudson Bay cousins do. So much depends on their ability to adapt.
      "We’re really changing the rules on the bears with the warming that we’re observing," he said. 
      Source: https://www.washingtonpost.com/news/speaking-of-science/wp/2016/04/21/melting-arctic-ice-is-forcing-polar-bears-to-swim-for-more-than-a-week-without-rest/?tid=sm_tw
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