Salt marshes are among the most ecologically productive and diverse ecosystems in the United States. They provide important services such as floodwater storage and storm protection for coastal cities such as New Orleans. Healthy marshes also serve essential roles in carbon sequestration, a service of primary concern at current emission rates of the greenhouse gas carbon dioxide, nutrient removal and water purification. However, global climate change and sea level rise, agricultural and industrial development and loss of sediment supply are contributing to dramatic rates of wetlands loss worldwide.