US Coastal Areas Most Threatened by Climate Change

by Cat Lazaroff

Climate change in this century may cause coastal erosion, coral reef die-offs and other serious impacts on US coastal and marine resources, according to a recent report from the National Oceanic and Atmospheric Administration’s National Ocean Service.

“While there are still important uncertainties associated with the assessment, it is clear that critical coastal ecosystems—like corals, wetlands and estuaries—are becoming increasingly stressed by human activities,” said a NOAA spokesperson. “The climate related stresses described in the report will certainly add to their vulnerability.”

The report, “The Potential Impacts of Climate Change on Coastal and Marine Resources,” indicates that climate change will add to the stresses already impacting coastal and marine resources, as a result of increasing coastal populations, development pressure and habitat loss, over-fishing, nutrient enrichment, pollution and invasive species.

Said NOAA Administrator D. James Baker, “It is very important for Americans...to be aware of the risks and potential consequences that future change will pose to their communities and their livelihoods.”

According to the report, corals have experienced unprecedented increases in the extent of bleaching, emergent coral diseases, and widespread die-offs in recent years. The impact of increasing atmospheric carbon dioxide on ocean chemistry is likely to severely inhibit the ability of coral reefs to grow and persist in the future, further threatening these already vulnerable ecosystems, the researchers concluded.

Sea level will continue to rise, and the developed nature of many coastlines will make both human settlements and ecosystems more vulnerable to flooding, the NOAA researchers said. Barrier islands are particularly vulnerable to the combined effects of sea-level rise and uncontrolled development.

Choices will have to be made between the protection of human settlements and the protection of coastal ecosystems such as beaches, barrier islands and coastal wetlands, the researchers warned.

Increases in precipitation and runoff are likely to intensify stresses on estuaries in some regions, by increasing the flow of nutrients and contaminants into coastal ecosystems. In contrast, the flow of sediments from rivers and streams could decrease, reducing the amount of soil and sand available to maintain wetlands, beaches and shorelines.

Changes in ocean temperatures and currents will affect the distribution, abundance and productivity of marine populations, with unpredictable consequences to marine ecosystems and fisheries, the report noted.

Increasing carbon dioxide levels could trigger abrupt changes in ocean circulation driven by differences in the density of seawater, which is controlled by the effects of temperature and salinity. This can result in massive consequences for the oceans and for global climate, the report found. Moreover, extreme and ongoing declines in the thickness and extent of Arctic sea ice will have enormous consequences for Arctic ecosystems.

With the US coastline stretching over 95,000 miles, and the nation’s economy dependent on the goods and services that it provides, changes in the marine environment could have major environmental and economic consequences.

“Most coastal resource management programs are not yet taking climate change into account in their goals and plans,” said Donald Boesch, Ph.D., the other co-chair of the assessment and president of the University of Maryland Center for Environmental Science. “[T]here is now clear evidence of a changing climate, (and) these programs should clearly begin to take (this) into account...over the next several decades.”

More information on the report is at: www.nacc.usgcrp.gov.