Description
In 2006, the Intergovernmental Panel on Climate Change noted that 11 of the last 12 years ranked among the 12 warmest years in the record of global surface temperature. The rising global temperature has increased water output from glaciers and ice sheets and caused thermal expansion of the ocean. These changes have ultimately raised the mean tide level globally, and new available data on the ice dynamics in Greenland and Antarctica have led some to suggest the sea level rise will be as much as to 1.5 or 2 meters above current levels. Natural coastal areas such as wetlands will be vulnerable to sea level rise of 1.5 or 2 meters. In this study, a high resolution digital elevation model (which was created by combining available Light Detecting and Ranging (LIDAR) data and the National Elevation Dataset) and the National Wetlands Database were used to run the Sea Level Affecting Marshes Model (SLAMM) in the coastal areas of San Diego County, San Diego Bay, and the Tijuana Estuary for a 1, 1.5, and 2 meters sea level rise. In this study, San Diego County salt marsh areas including transitional salt marshes make considerable gains countywide due to inundation of brackish marsh areas by 2100. In San Diego Bay, beach areas, brackish marshes, and tidal flat areas are reduced and salt marsh increase as a response to sea level rise. In Tijuana Estuary, ocean beaches, brackish marshes, swamps, and undeveloped dry land show significant reductions, while estuarine beaches and estuarine open water increase their areal cover. The study showed that sea level rise driven growth of salt marshes will expand the nesting grounds for the Belding's Savannah Sparrow and Light-footed Clapper Rail countywide. The inundation of estuarine beaches in San Diego Bay make it less suitable for California Least Tern and Western Snowy Plover to nest, while the formation of estuarine beaches (because of the inundation of undeveloped lands) on the south side of the Tijuana Estuary make it more suitable for these same two species of birds. Tidal flats in the southern part of San Diego Bay become inundated by SLR, making the Bay less suitable for foraging by shorebirds such as the Long-billed Curlew. Due to the implications of this research, it will be beneficial to designate and protect areas where critical habitats that support threatened and endangered species will migrate to as current protected areas such as the San Diego Bay Wildlife Refuge become inundated as the sea level rises.
