The Outer Banks Community, or OBX, consists of numerous barrier islands divided by inlets that connect the Atlantic Ocean to estuaries separating the islands from the mainland. The community has a maximum elevation of seven meters at the center, and width averaging only a few hundred meters reaching a maximum of four kilometers only in a few areas (Pendleton et al., 2004). These narrow strips of land stretch down the coast where tourism dominates the community economy followed by commercial and recreational fisheries and the real estate business. The late spring, summer and early fall peak tourist seasons provide the locals with a majority of the capital needed to live in the area during the slower, off-season months. The island community is home to a population of roughly 35,000 people year round (The Outer Banks Chamber of Commerce, 2016).
Increased Storm intensity and Frequency
Tropical storms and hurricanes are commonplace in the outer banks. As climate change continues to increase ocean temperatures, the storm season is extended in addition to increases in storm intensity. Storms, usually in the form of hurricanes threaten the islands with overwash, breaching, and storm surge often causing damage to homes, buildings and island infrastructure via flooding and high wind speeds, the need for beach restoration and in rare cases cause death.
While the current global rate of sea level rise is estimated at 3.2 mm per year, the OBX along with many areas around it is experiencing a rate of 3.71 mm or rise per year (Pendleton et al. 2004, Field et al., 2014). Sea level rise leads to increasing rates of shoreline erosion, inundation of wetlands and estuaries, saltwater intrusion to groundwater aquifers and additionally threatens the survival and stability of infrastructure and damages homes and buildings with flooding.
Vulnerabilities and Exposures
History of the Barrier Islands
The North Carolina barrier islands have a history of shoreline migration, inlet formation, and island shifts that make this community naturally vulnerable. The islands experienced a collapse approximately 1,100 years ago resulting in a sub-aerial shoal that allowed ocean water to enter the estuaries without obtruction (Culver et al., 2007). The submarine shoal lasted for hundreds of years only to rebuild naturally and take the form that it does today by about 1584 (Culver et al., 2007). As the islands were rebuilding both the size and number of inlets separating them were much greater than before the collapse (Kemp et al., 2017). Shifts in inlet formation are natural tools which provide the islands with the fluidity to adjust and survive during extreme weather events. These extreme weather events were major contributors to the collapse which either resulted from one major hurricane or multiple hurricanes within a relatively small time frame; similar to those that hit the Gulf Coast in 2004 and 2005 (Culver et al., 2007). The warmer temperatures that led to the increased hurricane intensity as well as the rate of sea level rise that the region experienced at the time of the island collapse are extremely similar to temperatures and sea level rise observed today. These in combination could lead to a collapse similar to that of the outer banks in the recent past.
- Storm relief occurs in order to maintain infrastructure and rebuild the community, however this disrupts the natural processes that overwash and erosion contribute to island survival. Storm overwash and the erosion of dunes, carry sediment to the interior and thus build the islands elevation. But human intervention limits this natural process by repurposing sediment and overwash to rebuild damaged portions of the islands. These exacerbate the problem and in combination with rising sea levels and the subsequent increase in overwash events, a positive feedback loop could arise with more aggressive tidal inlet formation, migration, and overall shoreline changes (DeWan et al., 2010).
- Relative sea level rise in the barrier islands is observed at 3.71 mm per year, a roughly 0.5 mm increase per year from the global mean which places the region at the highest level of vulnerability to this issue (Pendleton et al., 2004). Because the outer banks is an extremely low-lying island community, the anticipated roughly 1 m rise in sea level by 2100 would have serious consequences. Models suggest that a 0.9 meter rise in sea level would yield predicted erosion rates of 2.5 times higher than current ones and although the portions of the islands would survive, a majority of the community would fall under the waterline (FitzGerald et al., 2008). However when a 1.4 to 1.9 meter rise was simulated, it was discovered that this would most likely result in a collapse similar to that of the outer banks history (FitzGerald et al., 2008).
- The tourism industry in the outer banks accounts for roughly 6% of North Carolina’s 17 billion dollar tourist industry which equates to over one billion dollars a year (Edgell et al., 2010). Of the 35,000 people that inhabit the barrier islands, the tourist industry employs 20,000 of those residents in order to continue to provide for the hordes of visitors that travel to its beaches every year. The revenue and employment in this industry are at risk from climate change, especially as storms continue to skim millions of dollars off of the industry to pay for efforts to sustain the integrity of the islands and their attractions. In recent years new residents have increased in moving to the area and although this is a good sign for the economy of the islands, the issues of climate change are exacerbated with increases in infrastructure and adds additional difficulty in evacuation during storms (Edgell et al., 2016).
- In addition to the anthropogenic community risks, the outer banks is home to a great many wildlife communities that are at risk of climate change. One of the most important species of the barrier islands are sea turtles. Sea turtles are a particularly vulnerable because they are endangered in this region. The barrier islands offer migratory paths and foraging areas for this species as well as providing nesting areas and spawning grounds for sea turtles (DeWan et al., 2010). Sea turtles that inhabit this region are extremely susceptible to inundation in even the most conservative sea level rise estimates (DeWan et al., 2010). There have been great strides in regulation and protection of these animals on the outer banks in recent years in an attempt to help population rates rebound, however these developments could be for not if sea levels continue to rise along the coastline.
Adaptation and Resilience
National Geographic 2014
"You can't live here if you're not hearty, those people get washed away just as the storms come and go" - Resident of Hatteras Island since 1974
Residents of the OBX are resilient people who deal with home- and community-destroying storms every year. Many of them do not plan on leaving any time soon and risks of increasing storm intensity or sea level rise do not deter them from standing their ground.
Although there are few adaptive actions that will ensure the community's survival, there are actions that can be taken in order to help ease the burden of climate change:
- Assure maintenance of a safe and secure recreational environment as well as general ecosystem health
Examine the need for beach restoration, including beach re-nourishment (for example in Nags Head in the Outer Banks, the community implemented a tax increase to generate $36 million for beach nourishment that begins in July, 2011)
Determine whether structures like jetties, groins, or seawalls are needed along the coastline
Work toward sound policies for wildlife and habitat conservation
Develop educational/awareness programs to explain climate change impacts
Advocate good waterway and coastal management practices
Provide developers and agencies with risk assessments to guide development
- Review opportunities for resource savings with respect to energy
Work with locals to utilize traditional ecological knowledge (predictions of storm intensity, flood propensity via rain patterns, observations of sea grass, tide variance on the Pamlico Sound) in order to better predict and prepare for storms and flooding
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