1. August 8, 2016EXPERIENCE YOUR AMERICATM
Introduction
Sea level rise, an effect of global climate change, is
impacting 111 National Park Service (NPS) sites
nationwide. Sea level rise is caused by three primary
factors:
 Thermal expansion: as global temperatures rise,
ocean water expands, taking up more space as a
result.
 The melting of glaciers and polar ice caps increases
the amount of liquid water in the ocean.
 Loss of land-based ice in Greenland and West
Antarctica increases the amount of liquid water in
the ocean.
At George Washington Memorial Parkway (GWMP), the
natural and manmade landscapes that occupy low-lying
elevations are extremely vulnerable to its destructive
impacts from sea level rise. Sites along the parkway and the
parkway itself are home to many rare plant and animal
species and national historic treasures. Some GWMP
ecosystems and historic sites may have difficulty adapting
to rising sea levels. Fortunately, GWMP is already working
hard to preserve and protect these resources. The NPS
believes it is important to educate and engage GWMP
visitors about the threats posed by sea level rise, as its
impacts will have far reaching effects on the sustainability of
the park.
Impacts on Park Operations
Sea level rise is a concern for the GWMP, as it is home to
many miles of shoreline along the Potomac River. The rate
of relative sea level rise along the tidal Potomac River in
Washington, D.C. is roughly .13 inches (3.22 mm) per year
according to the National Oceanic and Atmospheric
Association (Sanders, G. and others, 2015). Rising sea
levels can permanently inundate wetlands and destroy
habitat. Moreover, when water flows into lower elevation
areas, the effects of extreme weather events caused by
climate change are exacerbated and can lead to even
worse flooding. Increasingly frequent extreme storms are
expected as a result of climate change. Residential
communities adjacent to coastal parks are also threatened.
The ecological resources found on the shorelines support a
variety of wildlife native to the National Capital Region
(NCR), including the only known breeding population of
marsh wrens in the area. Housing communities next to
coastal parks also depend on our vulnerable coasts.
Increased erosion, coastal flooding, and extreme storms are
already beginning to be observed.
Table 1. Short- and longer-term projections for sea level rise
in Maryland (2050 and 2100) based on semi-empirical
models (Boesch, et al. 2013).
Projection Relative Sea Level Rise
2050 Low 0.9 feet (0.3 meters)
2050 Intermediate 1.4 feet (0.4 meters)
2050 High 2.1 feet (0.7 meters)
2100 Low 2.1 feet (0.7 meters)
2100 Intermediate 3.7 feet (1.1 meters)
2100 High 5.7 feet (1.7 meters)
Site Specific Impacts
Dyke Marsh: Dyke Marsh is one of the most recognized
resources of the park and most vulnerable to flooding and
erosion. Because of its unique low-lying location, significant
habitat changes are likely to occur by 2080 (Sanders, et al.
2015). The rate at which sediment or soil builds up,
accretion, will not be enough to keep up with the rate of sea
level rise. This will likely transition the marsh to a new
vegetation structure. It is predicted that the marsh will be
submerged and converted into mudflats by 2080. Moreover,
marsh habitat will move further landward and threaten
forested habitat. The health of GWMP and the biodiversity it
provides depends on Dyke Marsh’s important ecosystem.
Fortunately, the NPS and the U.S. Army Corps of Engineers
are committed to restoring Dyke Marsh since dredging
operations ended in 1974. In 2013, Congress recognized
the serious threat of sea level rise on the marsh and
allocated $24.9 million to restore the site.
Sea Level Rise
at George Washington Memorial Parkway
National Park Service
U.S. Department of the Interior
Center for Urban Ecology
National Capital Region
Subject Guide and Interpretation Strategies for Rangers
Bike riders on the Mount Vernon Trail of the GWMP.
NPS Photo/Sam Sheline

2. August 8, 2016EXPERIENCE YOUR AMERICATM
Roosevelt Island: While the innermost memorial structures
are elevated enough to remain above sea level rise water
levels, the island itself will flood, limiting access and
recreational opportunities. Infrastructure (i.e. bridges,
walkways, parking lots, etc.) will have to be rebuilt in order
to maintain access to this important cultural and recreational
resource.
Jones Point: Sea level rise threatens Jones Point’s
historical treasures; the 1855 Jones Point Lighthouse, one
of the last riverine lighthouses in the country, and the 1794
original south corner boundary stone for Washington D.C.
Gravelly Point: Gravelly Point, a popular place to watch
airplanes land and take off over the Potomac, is projected to
be entirely underwater with only very minor rises in sea
level. Significant habitat changes along the coast are likely
to occur and threaten the site’s recreational value.
Infrastructure: Significant portions of the parkway may be
underwater due to sea level rise, leading to increased wear
and major changes to the road’s path. In addition to being
an inconvenience for commuters, the increased wear of the
parkway represents a loss of historic value. As the federal
government's first modern highway, the parkway was
intended to be a model to the nation and to encourage
pilgrimages to Mount Vernon.
Engaging Potential Audiences
Despite scientific consensus on its existence and causes,
climate change remains a controversial topic to the public at
large. Awareness of these realities and the spectrum of
beliefs you may encounter will allow you to engage your
audience most effectively. The George Mason University
Center for Climate Change Communication and Yale
University’s Project on Climate Change Communication
collaborate to create the “Six Americas” guide on
Americans’ views on climate change.
Synthesizing this information and applying it in the context
of your park will allow for the creation of more effective
communication strategies for the various visitors
encountered - from climate change deniers to avid
environmentalists. More information about the “Six
Americas” is available online at
http://www.climatechangecommunication.org/ and
http://climatecommunication.yale.edu/ . A report on utilizing
the “Six Americas” study in the context of National Parks
was published in Park Science by Karen Akerlof, Gregg
Bruff, and Joe Witte in 2011. It is a short, useful primer on
these population segments and how their views on climate
change shape their reactions to various forms and styles of
messaging.
Aware of the challenges of effective climate messaging, the
National Park Service has chosen to facilitate climate
conversations. Rather than directly contradicting denialist
beliefs or attempting to shame people into taking actions to
mitigate climate change and lessen their contribution to it,
we focus on creating personal connections to climate
change.
Site Specific Communication
Strategies
The National Park Service, through its Climate Change
Response Program, firmly believes that every person and
every place has a climate story. That is, everyone is
impacted by the diverse impacts of climate change and has
the ability to craft engaging stories that compel action on
this matter. Simple, short narratives are best suited to
communicate these site-specific stories with the public.
The “And, But, Therefore” communication strategy or “ABT”
is a novel and effective method (Olson, 2015) for
communicating the causes, impacts, and relevance of
complicated academic and scientific subjects. In this
method, two related facts or pieces of evidence are
presented, followed by a complicating statement and then,
finally, a resolution. This method simplifies information in
ways visitors from all backgrounds may understand, find
interesting, and apply to their lives. Additionally, it allows
interpretation to end on a hopeful note that inspires action.
EXAMPLE INTERPRETIVE STORY:
Dyke Marsh is experiencing erosion in addition to sea level
rise AND this poses a threat to not only the marsh but the
GWMP and the surrounding community BUT the marsh acts
as a natural buffer and the NPS is involved in restoration
efforts to mitigate or lessen impacts of sea level rise
THEREFORE we should recognize Dyke Marsh as an
undervalued natural resource and not only support NPS
restoration efforts actively take steps in our personal
behavior to combat climate change and sea level rise.
More Information
Ann Gallagher, Science Education Coordinator
Natural Resources & Science, NPS National Capital Region
Email: ann_gallagher@nps.gov | Phone: 202-339-8320
https://www.nps.gov/cue/uerla/
To cite this article: Hupper D., Mitch N., and Sheline S.
2016. Resource Brief: Sea Level Rise at George
Washington Memorial Parkway
References:
Akerloff, K., G. Bruff, and J. Witte. 2011. Audience
segmentation as a tool for communicating climate change:
Understanding the differences and bridging the divides. Park
Science 28(1):56–64.
Boesch, D.F., L.P. Atkinson, W.C. Boicourt, J.D. Boon, D.R.
Cahoon, R.A. Dalrymple, T. Ezer, B.P. Horton, Z.P. Johnson,
R.E. Kopp, M. Li, R.H. Moss,A. Parris, C.K. Sommerfield.
2013. Updating Maryland’s Sea-level Rise Projections. Special
Report of the Scientific and Technical Working Group to the
Maryland Climate Change Commission, 22 pp. University of
Maryland Center for Environmental Science, Cambridge, MD.
Olson, Randy. 2015. Houston, We Have a Narrative: Why
Science Needs Story. Chicago, IL: University of Chicago
Press.
Sanders, G., Elmore, A., Engelhardt, K., Fitzpatrick, M., Guinn,
S. 2015. Modeling the Potential Impacts of Sea-Level Rise on