Answer
Earth's rotational inertia would increase.
By conservation of angular momentum, the Earth's angular velocity would decrease, and we would have longer days as it would take a longer time for the Earth to complete each rotation.
Work Step by Step
If ice near the poles melted, the water would move away from the poles and spread more evenly around the earth. That is, more mass would be located farther from the Earth's axis of rotation. The result would be that the Earth's rotational inertia would increase.
By conservation of angular momentum, the Earth's angular velocity would decrease, and we would have longer days as it would take a longer time for the Earth to complete each rotation.
