Coastal Cities of Southern Virginia Among the Most Vulnerable in U.S. to Climate Change by mid-Century

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Climate change threatens Virginia's low-lying coastal cities with a costly combination of rising seas and more intense coastal storms. 

In October, the remnants of Hurricane Ida brought coastal areas of southern Virginia an unwelcome taste of the future: record storm surges and coastal flooding.  A combination of land subsidence and rising absolute sea levels mean that relative sea level has increased more than a foot for some areas of southern Virginia's coast.  A much greater rise in sea level is in store this century, along with more intense coastal storms -- and bigger storm surges. A year ago the Governor's Commission on Climate Change warned of the consequences of the trends; and last week WWF released a report indicating that climate change will dramatically increase the value of exposed assets in the Virginia Beach area -- from the current $85 million to potentially near a half billion dollars by mid-century.

According to Jeff Masters writing at the Weather Underground blog (Record Storm Surges Hit Mid-Atlantic Coasts, 13 November 2009), Norfolk was flooded by a record storm surge of 5.96 feet on 12 November.  According to Masters:

The storm surge flooding in the Norfolk area was exacerbated by the fact that sea level has risen and the land has subsided significantly over the past century. Over the past 60 years, absolute sea level along the coast of Virginia has risen by about 2.6 mm/year. However, the relative sea level has risen by 4.44 mm/year since 1927, meaning that the land has sunk by about 1.84 mm/year. The net result is that the ocean is now about 1.16 feet higher at Norfolk than it was in 1927. The Norfolk tide gauge shows the highest rate of relative sea level rise of any gauge on the U.S. East Coast (though relative sea level rise is much higher along the Gulf Coast, with rises near 3 feet/century at New Orleans). Thus, today's 5+ foot storm surge brought water more than a foot higher in Norfolk than the 5+ foot storm surge of the 1933 hurricane. Storm surge damages will steadily increase along the entire coast this century as sea level rise accelerates and coastal development continues. It is urgent that government take action in coming years to limit development in vulnerable coastal regions. The ocean is going flood our sand castles that we are building in harm's way, at an ever increasing rate.

Last December the Governor's Commission on Climate Change warned in its Climate Change Action Plan [PDF] that "Sea level rise is a major concern for coastal Virginia, particularly the highly populated Hampton Roads region."   According to the report, the Chesapeake Bay Program’s Scientific and Technical Advisory Committee projects that sea levels in the area will be 2.3-5.2 feet (0.7-1.6 meters) higher by 2100.  Among the commission's other conclusions:

  • "Based on an analysis by RMS (a catastrophe modeling company) that has been reviewed and approved by the Organization for Economic Cooperation and Development (OECD), the Virginia Beach-Norfolk Metropolitan Statistical Area ranks 10th in the world in value of assets exposed to increased flooding from sea level rise."
  • "Climate changes such as sea level rise pose serious and growing threats to Virginia’s roads, railways, ports, utility systems, and other critical infrastructure."
  • "Climate change is widely viewed as a threat to national security. In Virginia, there are several major military installations located in low-lying areas that will be affected by sea level rise and storm surge."
  • "The continued affordability and availability of insurance for Virginia’s landowners is a concern as our climate changes. These effects already are being felt in coastal Virginia."
  • "The frequency and severity of storms in the future are expected to exceed those of the past, and the insurance industry may not have the ability to handle several concurrent events."

The economic consequences were underlined last week, when WWF and the leading insurer Allianz SE released a report warning that sea level rise could dramatically increase risks to buildings, transportation infrastructure and other assets exposed to severe storm surges in coastal areas of the U.S. (see Climate Change Puts Trillions of Dollars in Assets at Risk Along U.S. Coasts, 23 November 2009). Virginia Beach was identified as one of the top 20 cities in the world with the highest increase in exposed assets associated with a 26 inch sea-level rise and a large storm surge in mid-century.  The study estimates that the current asset exposure is $84.6 million. Exposure by mid-century could be $462 million.

The 26 inch sea-level rise along the mid-Atlantic coast assumed in the WWF/Allianz study by mid-century consists of a 20 inch (.5 meter) global sea level rise and a 6 inch (.15 meter) local sea level rise associated with a change in ocean circulation along the Northeast coast.  According to research published in Geophysical Research Letters, the northeast could see a localized sea level rise of 12-20 inches above global sea levels by the end of the century (see NSF press release Sea-level Rise May Pose Greatest Threat to Northeast U.S., Canada, 27 May 2009). 
The sensitivity of local sea level to changes in ocean circulation was dramatized this summer along the entire East Coast when sea levels were six inches to two feet above normal during June and July. One of several principal reasons for the anomaly was a weakening of the “Florida Current Transport.”
According to NOAA, the Florida Current Transport is “a return pathway for the Thermohaline Overturning Cell, which consists of a slow circulation redistributing the waters of the world ocean based on sinking at the high latitudes and upwelling elsewhere. The Thermohaline Overturning Cell has been documented to have strong impacts on the global climate, and as such variations in the Florida Current, which returns surface waters to the northern North Atlantic, represent an important climate signal to be monitored.” [emphasis added]
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