Sea-Level Rise & Global Climate Change:  A Review of Impacts to U.S. Coasts

Eileen Claussen, President, Pew Center on Global Climate Change

Coastal regions play an integral role in the United States, serving as home to over half of the U.S. population, providing recreational opportunities to many, and supplying numerous valuable ecological services. At the same time, these areas are constantly evolving and face a wide range of natural and human-induced stresses, including erosion, storms, and pressures from development and recreational uses.

Current scientific research shows that climate change will lead to substantial sea-level rise along much of the U.S. coastline. Sea levels have already risen between 10 and 25 cm over the last century. Global warming will accelerate these rates, with sea levels projected to rise by 50 cm by 2100.

"Sea-Level Rise and Global Climate Change" is the fourth in a series of reports examining the potential impacts of climate change on the U.S. environment and society. This report finds that the vulnerability of a coastal area to sea-level rise varies according to the physical characteristics of the coastline, the population size and amount of development, and the responsiveness of land-use and infrastructure planning at the local level. The authors conclude the following:

• Low-lying developed areas in the Gulf Coast, the South, and the mid-Atlantic regions are especially at risk from sea-level rise.
• The rapid growth of coastal areas in the last few decades has resulted in larger populations and more valuable coastal property being at risk from sea-level rise. This growth, which is expected to continue, brings with it a greater likelihood of increased property damage in coastal areas.
• The major physical impacts of a rise in sea level include erosion of beaches, inundation of deltas as well as flooding and loss of many marshes and wetlands. Increased salinity will likely become a problem in coastal aquifers and estuarine systems as a result of saltwater intrusion.
• Although there is some uncertainty about the effect of climate change on storms and hurricanes, increases in the intensity or frequency or changes in the paths of these storms could increase storm damage in coastal areas. Damage to and loss of coastal areas would jeopardize the economic and ecological amenities provided by coastal wetlands and marshes, including flood control, critical ecological habitat, and water purification.

Damages and economic losses could be reduced if local decision-makers understand the potential impacts of sea-level rise and use this information for planning.

The authors and the Pew Center gratefully acknowledge Dr. Donald Boesch and Dr. George Parsons for their review of previous drafts of this report. In addition, the Pew Center would like to thank Joel Smith and Brian Hurd of Stratus Consulting for their management and oversight of this Environmental Impacts Series.