The Last Bear by Hannah Gold

Driven by a powerful intuition that her beloved polar bear friend is in danger, eleven-year-old April Wood convinces her father to return with her to the freezing tundra of the high Arctic. Once there, April embarks on a treacherous journey across glaciers and icy terrain to track down the injured bear. Along the way, she discovers an unexpected surprise—a tiny, defenseless polar bear cub desperately in need of rescue.