Final answer:
When sea ice melts, it does not impact sea level. However, the melting of land-based ice contributes to sea level rise.
Step-by-step explanation:
One true statement about sea ice is that when it melts, it does not impact sea level. This is because ice floating on the ocean is already displacing water, so the melting of sea ice does not cause any changes in sea level. However, the melting of land-based ice, such as glaciers and ice sheets, does contribute to sea level rise.