This document discusses the implications of rising sea levels for the Mid-Atlantic region. It identifies potential impacts such as inundation of dry land and wetlands, increased erosion, and saltwater intrusion. The document outlines three responses to sea level rise: retreat, armor the shoreline to hold back the sea, or elevate land surfaces. It predicts that under scenarios of accelerated sea level rise, some barrier islands in the Mid-Atlantic will erode or become submerged by 2050. The document concludes that regional planning is needed to reduce the economic and human impacts of sea level rise and that rolling easements and reconsideration of policies encouraging coastal development can help address these challenges.

1. IMPLICATIONS OF RISING SEA LEVEL FOR THE
MID-ATLANTIC
CHARLES M. CARUSO

2. IMPACTS OF SEA LEVEL RISE
• Inundation
– Dry land
– Wetlands
• Erosion
• Flooding
• Saltwater Intrusion

3. THREE RESPONSES TO
SEA LEVEL RISE
• Retreat
• Hold Back the Sea:
–Armor the Shore (dikes, seawalls,
bulkheads, rip-rap) or
Elevate Land Surfaces

4. POTENTIAL MID-ATLANTIC
SEA LEVEL RISE
Coastal Sensitivity to Sea-Level Rise:
AFocuson the Mid-Atlantic Region
ES.2.1 Sea-Level Rise and
the Physical Environment
The coastal zone is dynamic and
the response of coastal areas to
sea-level rise is more complex
than simple inundation. Erosion
is a natural process from waves
and currents and can cause land
to be lost even with a stable sea
level. Sea-level rise can exacer-
bate coastal change due to ero-
sion and accretion. While some
wetlands can keep pace with sea-
level rise due to sediment inputs,
those that cannot keep pace will
gradually degrade and become
submerged. Shore protection and
engineering efforts also affect
how coasts are able to respond
to sea-level rise.
For coastal areas that are vulner-
able to inundation by sea-level
rise, elevation is generally the
most critical factor in assessing
potential impacts. The extent of
inundation is controlled largely
by the slope of the land, with a
greater area of inundation oc-
curring in locations with more
gentle gradients. Most of the
currently available elevation
data do not provide the degree
of confidence that is needed for
making quantitative assessments
of the effects of sea-level rise
for local planning and decision
making. However, systematic
collection of high-quality eleva-
tion data (i.e., lidar) will improve
the ability to conduct detailed
assessments (Chapter 2).
Nationally, coastal erosion will probably
increase as sea level rises at rates higher than
those that have been observed over the past
century. The exact manner and rates at which
these changes are likely to occur will depend on
headlands, spits, and barrier islands will erode
at a faster pace in response to future sea-level
rise. For accelerations in the rate of sea-level rise
by 2 and 7 millimeters per year, it is likely that
some barrier islands in this region will cross a
The coastal zone
is dynamic and the
response of coastal
areas to sea-level rise
is more complex than
simple inundation.
Figure ES.1 Potential mid-Atlantic coastal landform responsesto threesea-level risescenarios
(in millimeters[mm] per year [yr]). Most coastal areasarecurrently experiencingerosion, which
is expected to increase with future sea-level rise. In addition to undergoing erosion, coastal
segments denoted with a “T” may also cross a threshold where rapid barrier island migration
or segmentation will occur.
Potential Mid-Atlantic Landform Responses to Sea-Level Rise

5. PROJECTED SEA
LEVEL RISE

6. ENVIRONMENTAL IMPACTS OF SEA
LEVEL RISE
The Rise Itself
Wetland Inundation
Erosion of beaches,
mudflats and wetlands
Saltwater intrusion into
estuaries, groundwater,
and wetlands
Water Tables-->Septics
Higher water
Effects of Response
Strategies
• Shoreline armoring
– Net wetland loss
– Lose Estuarine
Beaches
– Lose mudflats and
shallows
– Lost public access
along shore
• Failed septics induce
infrastructure

7. PROTECTION AND RETREAT
 Fundamental Pathways for responding to sea level rise:
 Shoreline armoring
 Elevate land, structures, wetlands
 Retreat
 Tradeoffs between different approaches
 Shore protection maintains existing land use
 Retreat allows natural processes
 Costs and social implications vary.
 Higher rates may shift the balance toward retreat

8. http://epa.gov/climatechange/effects/coastal/SLRBarrier_Islands.html

9. ROLLING EASEMENT
An interest in land (or a
rule of law) under which
the landward migration of
wetlands, beaches, and
public access along the
shore has the right of way
over a property owner’s
preference to hold back
the sea.
SAP 4.1 Coastal Sensitivity to Sea-level Rise
Rolling Easement
An interest in land (or
a rule of law) under
which the landward
migration of
wetlands, beaches,
and public access
along the shore has
the right of way over
a property owner’s
preference to hold
back the sea.

10. DEVELOPMENT, PROTECTION, AND
MORAL HAZARD
Anticipating Sea Level Rise
is Logically Justified
 Sea level rise changes
merits of
 Shore protection
 Home elevation
 Coastal development
 Flood insurance
 Can ensure that risks are
reflected in the cost of coastal
habitation
 key tool for ensuring safe
construction (e.g. floor elevation)
Institutional Biases:
 Policies encourage
coastal development
 Local policies
 Development a route to
federal subsidies
 Federal safety net for
development
 Subsidized shore protection
 FEMA programs that pay for
shore protection, home elevation,
relocation
 Flood Insurance
 Grandfathering of assumed risk:
 Sea level rise not included in
flood mapping.

11. CONCLUSIONS
-Sea level is rising along the Mid-Atlantic coastline at rates
that will lead to inundation of barrier islands by 2050
-planning now on a regional basis will reduce the
economic and human impacts
-rolling easements provide a set of tools to reduce
these impacts
-reconsideration of all federal, state and local
policies that encourage coastal development is
needed