The cyrosphere is one of the main stores of water, this also includes permafrost. Any crysopheric change can influence sea levels. For example, during a glacial period where there is significant cooling, the cyropshere grows in size. This is because ice restricts and slows down water flow into the seas and oceans.Whereas, in a period of warming, the cyrosphere adds water to the cycle, because ice melt contributes to oceans and seas. The increase in the size of water stores in the ocean evidently causes sea levels to rise and thermal expansion of water also occurs.