The potential impacts of climate change on the mid-Atlantic coastal region

This paper assesses the potential impacts of climate change on the mid-Atla ntic coastal (MAC) region of the United States. In order of increasing unce rtainty, it is projected that sea level, temperature and streamflow will in crease in the MAC region in response to higher levels of atmospheric CO2. A case study for Delaware based on digital elevation models suggests that, b y the end of the 21st century, 1.6% of its land area and 21% of its wetland s will be lost to an encroaching sea. Sea-level rise will also result in hi gher storm surges, causing 100 yr floods to occur 3 or 4 times more frequen tly by the end of the 21st century. Increased accretion in coastal wetlands , however, which may occur in response to increases in CO2, temperature, an d streamflow, could mitigate some of the flooding effect of sea-level rise. Warming alone will result in northward displacements of some mobile estuar ine species and will exacerbate the already low summer oxygen levels in mid -Atlantic estuaries because of increased oxygen demand and decreased oxygen solubility. Streamflow increases could substantially degrade water quality , with significant negative consequences for submerged aquatic vegetation a nd birds. Though climate change may have some positive impacts on the MAC r egion, such as increased coastal tourism due to warming and some ecological benefits from less-frequent harsh winters, most impacts are expected to be negative. Policies designed to minimize adverse ecological impacts of huma n activities on coastal ecosystems in the mid-Atlantic, such as decreases i n nutrient loading of watersheds, could help mitigate some of the risks ass ociated with future climate variability and change in this region.