HOW IS ADDED HEAT IS CONTRIBUTING TO SEA-LEVEL RISE? 1. MELTING GLACIERS AND ICE SHEETS AT THE POLES It’s simple physics: heat melts ice. When air and ocean temperatures rise, glaciers and ice sheets melt. The melted ice becomes water that flows into the ocean, either directly or running over land first. All that extra water then causes sea levels to rise. 2. THERMAL EXPANSION Water expands as it warms. Imagine a pot of water heating on the stove. The volume of that water in the pot expands as it heats up. Now imagine the entire ocean doing that. Scientists estimate that