the increased heat will melt the ice at the polar ice caps, then that freshwater will mix with the saltwater of the ocean, and the mixed water will effect the salinity of the ocean water in a way that stops the flow of warm water to the arctic circle and the flow of cool water to the equator. Then, the screwed up currents will contribute to a cooling period ( salt water's density is different from freashwater, causing the problem)
Then, once all the Ice is on the ground, it will reflect sunlight/UV radiation back into space, thus keeping the planet cool.