Polar ice sheets are large masses of ice that cover the land in the Antarctic and Greenland. They are formed from layers of snow that have compacted over time, creating thick ice. These ice sheets hold about 70% of the world's fresh water and play a crucial role in regulating the Earth's climate. As the climate warms, polar ice sheets are melting at an accelerated rate, contributing to rising sea levels. This melting can impact coastal communities and ecosystems worldwide. Scientists study these ice sheets to understand climate change and its effects on global weather patterns and sea levels.