Still more complete BS, repeated uncritically by your mainstream media: “On shore, there is no food available for [polar bears]”

Warmer Arctic Is Hindering Polar Bears - NYTimes.com

“On shore, there is no food available for them,” said Peter K. Molnar, a researcher at Princeton and lead author of the new study.

POLAR BEARS - Diet & Eating Habits

Polar bears feed mainly on ringed and bearded seals. Depending upon their location, they also eat harp and hooded seals and scavenge on carcasses of beluga whales, walruses, narwhals, and bowhead whales.
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When other food is unavailable, polar bears will eat just about any animal they can get, including reindeer, small rodents, seabirds, waterfowl, fish, eggs, vegetation (including kelp), berries, and human garbage.

Polar bear tours - Churchill Manitoba

The polar bears enjoy the ice until about mid-July. At this time the ice pack becomes too small for the bears to stay, so they swim for shore, landing somewhere on the hundreds of miles of shore line around and to the south of Churchill. At this time of year the bears become sleepy and groggy because they are generally fat and not eating any food. Polar bears will occasionally kill seals in the summer, if given an opportunity, but generally consider it too much work. They can be seen feasting on dead whale carcasses and chasing flightless geese. But for the most part, they are partakers of the couch potato lifestyle, resting on shore and sometimes inland where permafrost is close to the surface and a wallow can be dug to the frost.