"Shorelines are meant to move. With the rhythm of the ocean, the beat of storms, and the pulse of river sediment streaming into the sea, the intertidal zone grows and shrinks and repositions itself like a dancer responding to music. But chop off her stage and suddenly that dancer can?t groove the way she?s meant to. Permanent barriers along the shore—sea walls, dikes, buildings, paved roads, and the like—prevent the intertidal ecosystem from responding to rising sea levels and storms by migrating inland. As a result, the intertidal zone erodes and coastal habitats compress. Flood risk rises and groundwater becomes contaminated with salt water. Some scientists call this phenomenon ?coastal squeeze.”