Some polar bears are white to hide n the snow and others are darker due to a mutation.
Changes In Gene Pool
The penguins left the environment because it was no longer cold enough for them. This becomes overproduction on the polar bears side because they thought a lot of them would be killed be penguins as cubs but now they will all starve.
The tan bears will thrive as all the ice and snow melts as global warming kills off all white polar bears.
Only the tan bears survived because they were resistant to the heat and all of the white polar bears died off. Only tan bears will be born now.