Polar bears don't look for food on land unless they are take a nap. Calculation of Linda J. Gormezano suggest that the predators can survive for 6 months from the food that can find on the ground. Because the weather is change. When the climate warm, the sea ice doesn't last as long. from this cause the populations of polar bears has decline quite substantially. So the question is "How to make food enough for polar bears survive.