Re “Concern for future rises with waters’’ (Page A1, Jan. 5): Unfortunately, Thursday’s historic salt water flooding of downtown Boston will one day be all-too frequent. Coastal flooding has four ingredients: sea level, tide, storm surge, and our built environment. Winter Storm Grayson’s three-foot storm surge was actually pretty typical for a winter nor’easter, but it neared its peak during a full moon “wicked’’ high tide (add two feet above normal) augmented by sea level rise (add another foot since 1900). With seas six feet above normal high tide, Boston’s low-lying areas predictably flooded. Concerned residents can refer to Climate Ready Boston’s Map Explorer to see if their home or business is at risk.

Julie Wormser

Cambridge

The writer is the former executive director of the Boston Harbor Association and former vice president for policy and planning at Boston Harbor Now.