The second law of thermodynamics states that the entropy of an isolated system never decreases, because isolated systems spontaneously evolve towards thermodynamic equilibrium -- the state of maximum entropy.
No process is possible whose sole result is the transfer of heat from a body of lower temperature to a body of higher temperature.
When ice forms, energy passes to the surrounding environment, which must be at a lower temperature, and hence increases the entropy of the system comprising ice + environment. You cannot take the ice in isolation as there could then be no transfer of energy. The entropy of the ice may be decreased, but this is more than matched by the increase in the entropy of the environment.
A similar argument applies when ice melts. The increase in the entropy of the ice is more than the decrease in entropy of the environment.
No process is possible whose sole result is the transfer of heat from a body of lower temperature to a body of higher temperature.
When ice forms, energy passes to the surrounding environment, which must be at a lower temperature, and hence increases the entropy of the system comprising ice + environment. You cannot take the ice in isolation as there could then be no transfer of energy. The entropy of the ice may be decreased, but this is more than matched by the increase in the entropy of the environment.
A similar argument applies when ice melts. The increase in the entropy of the ice is more than the decrease in entropy of the environment.