By Sophie Hardach, BBC.  Excerpt: A photographer's iconic shot of polar bears in abandoned buildings on a Russian island shines a spotlight on wider changes in their behaviour. ...Smith notes that polar bears are  spending more time on land  due to the climate-change-driven  loss of sea ice . They are also shifting their dens from the ice onto the land, to avoid the risk of denning on the increasingly unstable sea ice,  research in northern Alaska  shows. Without the sea ice, the  bears can't hunt  for their  preferred, ideal diet  of  blubber-rich seals , and may  resort to land-based food , be it prey or rubbish. ...A 2022 research paper warns that food from human sources – especially waste – is an  emerging threat  to polar bears. The supply of such human-provided food including from dumps is growing, according to the paper. As a consequence, some communities in the Arctic have seen startling incursions of dozens o...

By Louise C. Archer et al, Science.  Summary: ...polar bear populations have declined over the past 50 years as the extent of sea ice has decreased. Archer  et al . used data collected from polar bears in the western Hudson Bay Area over nearly all of that time.... Energetic patterns at the individual level successfully predicted larger-scale population dynamics. A single driver, energy limitation, emerged as being responsible for the population decline, confirming that polar bears face food shortages due to the loss of ice. —Sacha Vignieri....  Full article at https://www.science.org/doi/10.1126/science.adp3752 . 

https://www.science.org/doi/10.1126/sciadv.adf3326 By MICHAEL V. WESTBURY et al, Science Advances.  Excerpt: The Arctic is among the most climatically sensitive environments on Earth, and the disappearance of multiyear sea ice in the Arctic Ocean is predicted within decades. As apex predators, polar bears are sentinel species for addressing the impact of environmental variability on Arctic marine ecosystems. ...we investigate how Holocene environmental changes affected polar bears around Greenland. We uncover reductions in effective population size coinciding with increases in annual mean sea surface temperature, reduction in sea ice cover, declines in suitable habitat, and shifts in suitable habitat northward. ...[over the past 11,000 years...Whenever temperatures rise, polar bear populations crash. For example, about 4500 years ago, sea surface temperatures climbed by 0.2°C, sea ice cover shrank by about 3%, and polar bear populations dropped by about 20%. Several thousand ...

https://www.theguardian.com/environment/2023/apr/10/a-jail-for-wayward-polar-bears-you-must-be-in-churchill-canada By  Zed Nelson , The Guardian.  Excerpt: Perched on the southern edge of the  Arctic  on the shores of Hudson Bay, residents of the Canadian town of Churchill share their streets with the world’s largest land carnivore. Their regular encounters with polar bears have earned Churchill the nickname “Polar bear capital of the world”. ...The 900 or so residents are used to looking cautiously around corners and not walking after dark. But it’s the bears that could claim to have a grievance: the town was built on their annual migratory route. ...Living side by side with apex predators certainly poses challenges for the town’s residents, but it is the spectre of climate change that looms large over Churchill. The number of polar bears in western Hudson Bay has fallen by  27% in the past five years , according to a recent government survey that counted bears...

https://www.nytimes.com/2022/06/16/climate/climate-change-polar-bears.html By  Henry Fountain , The New York Times.  Excerpt: Scientists have identified a distinct subpopulation of polar bears in southeastern Greenland that, in an area with little sea ice, survive by hunting from ice that breaks off glaciers. The discovery suggests a way that a small number of bears might survive as warming continues and more of the sea ice that they normally depend on disappears. But the researchers and other polar experts cautioned that grave risks to the overall polar bear population in the Arctic remain and will only be lessened by cutting greenhouse gas emissions to curb global warming. The subpopulation, believed to number several hundred animals, was identified during a multiyear study of what was thought to be a single population of bears along Greenland’s entire 1,800-mile-long east coast. ...Overall, there are an estimated 26,000 polar bears around the Arctic, in 19 officially design...

https://blogs.scientificamerican.com/extinction-countdown/polar-bear-plan-climate-change/ Source:   By John R. Platt, Scientific American For Investigation:   10.3 For GSS Climate Change chapter 8 and Losing Biodiversity chapter 8. Excerpt: Climate change is “the primary threat” to the survival of polar bears, according to a conservation management plan released today by the U.S. Fish and Wildlife Service. The plan—which also addresses issues such as human-bear conflict, subsistence hunting by Alaskan Native people, and minimizing the risk of oil spills—says global action on climate change is necessary to save this sea-ice dependent species, which has over the past several years become the conservation icon related to climate change. ...The 106-page plan addresses multiple issues facing polar bears, presenting a complex portrait of their threats and what it will take to save them....

http://www.nytimes.com/2016/12/18/science/polar-bears-global-warming.html Source:  By Erica Goode, The New York Times For Investigation:   10.3 Excerpt: ...Scientists have counted up to 80 [polar bears] at a time in or near Kaktovik; many look healthy and plump, especially in the early fall, when their presence overlaps with the Inupiat village’s whaling season. But the bears that come here are climate refugees, on land because the sea ice they rely on for hunting seals is receding. The Arctic is warming twice as fast as the rest of the planet, and the ice cover is retreating at a pace that even the climate scientists who predicted the decline find startling. Much of 2016 was warmer than normal, and the freeze-up came late. In November, the extent of Arctic sea ice was lower than ever recorded for that month.  ...The continuing loss of sea ice does not bode well for polar bears, whose existence depends on an ice cover that is rapidly thinning and meltin...