Unparalleled views of sea level rise ⬆️🌊🛰 Global sea levels have risen more than 4 inches (102 millimeters) since measurements began in 1992, increasing coastal flooding in some places. As ocean water warms, it expands and takes up more space. The added heat in the air and ocean is also melting ice sheets and glaciers, which adds freshwater to the ocean and further raises sea levels. The Surface Water and Ocean Topography (SWOT) mission, launched in 2022, and Sentinel 6 Michael Frelich, launch