IMPACT OF RISING SEA LEVELS ON NATIVE AMERICAN CULTURAL SITES IN SOUTHERN CALIFORNIA

Humans arrived in Southern California about 13,000 years ago, shortly after sea level began rising following the last glaciation. Most of their sites along the shoreline of the time (nearly 120 m below the present sea level) have been inundated and are unknown. Now hundreds of remaining sites on-shore are threatened, or will be threatened, in the foreseeable future by rising sea levels. A survey of prehistoric and historic human site elevations in Los Angeles, Orange, San Diego, and Ventura Counties reveals the 1.4 m rise in sea level expected in 2100 due only to the thermal expansion of sea water will impact 194 sites. If the ice on either Greenland or West Antarctica were to collapse or melt into the ocean, sea level would rise some 8 m and impact an additional 295 sites or 17 m and 434 sites if both collapse. If all the ice on Earth, including that on East Antarctica entered the ocean, sea level would rise about 80m impacting an additional 1246 sites for a total of nearly 2,200 archaeological sites . While each of these scenarios have different time estimates, the collapse of parts of the Greenland and West Antarctica ice sheets could happen soon and quickly, adding their sea level components to the estimates for thermal expansion (=18.5 m). The East Antarctic ice sheet is unlikely to collapse or melt for at least several hundred years. Rising sea levels within the next decades also endanger Native American sites by damage from erosion, storm surges, tsunamis, and extreme tides. Protection of human archaeological and historic heritage sites in coastal Southern California should be coordinated and included with efforts to reduce damage to modern infrastructure and buildings from sea level rise.