Check out the article linked below...as the ice caps at the poles melt, much of the melt water makes its way towards the equator (why do you this is?). This is changing the mass distribution of the earth to some small degree. Another name for the distribution of mass relative to an axis of rotation is the moment of inertia, or rotational inertia. This is causing changes in the earth's rotation. Think fast before reading the article: If the water moves towards the equator, what should happen to the period of the earth's rotation?
See if you are correct!