Is Miami Beach sinking?  So what exactly does that mean? The technical term is subsidence. It means the lowering of the surface due to the removal or compaction of materials below it. Sinkholes that open up primarily in central Florida are dramatic examples of subsidence. In the wake of the tragic collapse of a condominium in Surfside, just north of Miami Beach, that question came up again. But the real concern for Miami Beach is not about sinking.  Correspondent John Zarrella went to investigate what happened and to assess Miami’s vulnerability to climate change.