Norwegian…
I always mix them up … 
Polar bears are essentially aquatic. they swim from and walk around the pack ice and hunt seals. They bulk up on seal and then will come ashore in winter to nest, live off their fat, and have cubs. Of course, they are not above eating other tasty treats the find wandering the ice.
(Which reminds me of the advice I heard from someone who once lived in Churchill - polar bears basically eat seals. When they catch them, they pick them up by the back of the neck and shake them to break their neck; then they can eat them without a fight. So, if you are ever trapped in the open by a polar bear, lie face down and put your hands over the back of your neck. That way you will live, maybe an extra 10 seconds, that it takes the bear to bite your hands off before his jaws can get a grip on your neck. )
A polar bear is white because its fur is, I think, hollow (the inspiration for artificial holofil clothing insulation). They need the protection to be able to swim in sub-zero temperatures of the salty ocean.
If anyone saw “march of the penguins”, they go about 60 miles inland to nest and raise the young to protect themselves from shoreline predators. I’m not sure how adventurous polar bears might be, but I imagine they could sniff out the inland colonies; although the penguins would be in danger once at the shore. However, they probably can swim faster and deeper than polar bears, so once in the water they might be safe (except for the seals). Presumably bears could catch seals the way the always have - expect the arctic was a collection of relative sheltered islands, tundra and flat pack ice, whereas my impression of the Antarctic is that there are a lot of “hilly” cliff-ice shoreline and heavy waves where a bear might have difficulty getting ashore.
Polar bears in Africa - would they have time to adapt? The problem is that most adaptations take place gradually. Plus, what would they eat? Most of the decent-sized meals are already evolved to get away from faster predators, and definitely any polar bear would overheat trying to chase down a gazelle … although polar bear vs. rhino, hippo, or elephant might be an interesting idea - I wonder if the Romans already did that?
No. “Crazy” Swedes.
True. But let’s examine the other part of kanicbird’s statement - that the penguins are at sea in summer and on land in the winter. If polar bears were there in winter, I could see them easily demolishing penguin colonies left and right by eating the nesting adults and crushing the eggs. I could see healthy colonies being wiped-out entirely in one season this way with only a few bears.
On the other hand, during the Antarctic summer, when the penguins are at sea for the most part, what would the bears eat? There are no walrus herds or garbage dumps to raid. There could be a beached whale here and there, but I am not sure there is enough summer forage for the bears to survive there, as opposed to the arctic, where the seas are bordered by somewhat productive tundra that can support other potential game for the bears - perhaps freshwater fish.
So, maybe the bears would be able to feast in the winter but would starve the first summer. Maybe they’d only survive one year?
That’s Emperor penguins. How about they snack on these.
Then it’s not the bears you’d have to worry about, but the dogs.
Let’s get ready to ruuuuuuumble!
Relevant Far Side cartoon
Great minds think alike?
http://www.polarbearsinternational.org/about-polar-bears/what-scientists-say/antarctica
The penguins would flap their flippers so rapidly in fright fleeing the bears that they’d quickly realize, *“hey, look at that, we can fly after all!” *
…thus returning joy and harmony to the penguin community once again. 
It’s been awhile since I read about this stuff in my first year ecology class, but no, those canonical oscillating cycles you’re thinking of don’t always happen. Sometimes you end up with the situation Mr. Kobayashi outlined where one or both species go extinct. Which outcome you end up with is going to depend on things like the reproductive rates of the penguins, whether they can find refuges, how the growth rates and predation rates change with density, etc…
Polar bears hunt in the summer while the ice is breaking up, they can swim very long distances from pack ice to pack ice. They hang around the ocean and pack ice where they find a lot of seals, as there is not a lot of large food-bearing mammals wandering the dry land. The ice typically locked in during winter blizzards, so in the winter, they nest and live off accumulated body fat. During this nesting is when the cubs are born. Amazingly, they will go several months without eating.
(A common point made about endangered polar bears is that the pack ice is becoming thinner and more spread out, the bears swim longer, find less food. When it comes time for winter “hibernation” - nesting - they do not have the accumulated body fat to make it through the winter.)
Polar bears don’t live inland in the Arctic for the most part. Why would they go to a less familiar habitat with less food?
Everyone likes a change of pace sometimes.
Interesting that someone has find a practical dimension on this: saving the polar bears this way!
How about eskimos then: do you think they could live in Antarctis?
Highly unlikely if you mean survive multi-generationally as traditional subsistence hunters. There are no animals to hunt for fur. Penguins, Seals, Whales and Fish is it… There are also a number of berries and grasses that formed part of the traditional inuit diet that wouldn’t be available in antarctica.
:dubious: What kind of fur do you think Inuits usually most use?
Thios is true enough.
All the Inuits I’ve known were nudists.