If earths temperature rises, could oceans expand enough so that earths rotation could slow?
Well, yes. If the icecaps melt, the mass that was on the poles will redistribute itself closer to the equator. In doing so, it will increase the moment of inertia, which is kind of like the mass, but for a rotational system. Since rotational momentum will be constant, but the inertia goes up, the speed of rotation will go down. So the melting of the icecaps will affect the rate at which the earth rotates. There is a secondary effect, that the oceans will expand because they are hotter. This too will increase the moment of inertia and slow the rate of rotation. However, liquids do not expand much when heated, so this effect will be extremely small. The icecap thing would be a much larger effect than the water itself expanding, but neither effect would be noticeable. These types of affects are all going to be very very small because the increase in the moment of inertia, in either case, is going to be a tiny increase relative to the already massive moment of inertia for the earth. That m
