The Barataria Basin was built of soil washed to the area by the Mississippi River, and that soil is still compacting and sinking in a process called subsidence. Most of the Barataria Preserve is less than two feet above sea level, and its subsidence rate is nearly half an inch a year. At the same time, melting glaciers and polar ice sheets and warming oceans are raising sea levels globally as ocean water expands with heat. The combination of sinking land in the Barataria Basin and global sea level rise is causing the ocean to creep in faster here than almost anywhere else in North America, bringing more frequent and longer-lasting floods, disappearing coastal wetlands, less land to buffer Gulf of Mexico storms, greater storm and flooding threats to homes, communities, highways, ports, and energy facilities, salt water moving into freshwater wetlands and killing plants that hold the land together, and the deaths of plants, animals, and microbes that cannot tolerate increased flooding or saltwater.