Climate Change Indicators in the United States: A Closer Look: Land Loss Along the
Atlantic Coast - www.epa.gov/climatechange/indicators - Updated May 2014
A Closer Look: Land Loss Along the Atlantic Coast
Rising sea level tends to make headlines during
extreme events, like the storm surge that caused
billions of dollars in damage during Hurricane
Sandy in 2012. Yet rising sea level can also cause
permanent changes in the landscape when it
inundates (submerges) low-lying land. The Atlantic
coast is particularly vulnerable because of low
elevations and sinking shorelines.
The loss of coastal land can affect a large number
of people, as nearly 10 million Americans live in a
coastal floodplain.1 Coastal ecosystems are also at
risk. These environments provide habitat for many
kinds of plants and animals, as well as services that
ensure people's well-being, ranging from food
production to recreation. Coastal wetlands provide
valuable nursery, feeding, breeding, staging, and
resting areas for many fish, shellfish, mammals,
and birds, and they can buffer coastal areas against
storm and wave damage.
As sea level rises, dry land can turn into wetland or open water. Existing wetlands can be threatened,
too, as salt marshes, mangrove forests, and other coastal wetlands are at risk of being converted to
open water.
The Sea Level indicator shows that sea level is rising overall in connection with climate change, but the
rate of change varies by region, as do the effects. To provide a useful regional perspective, this feature
examines the amount of land lost to sea level rise along the Atlantic coast from Florida to New York. It is
based on satellite data that have been collected and analyzed at five-year intervals since 1996. Figure 1
divides the Atlantic coast into two regions for comparison, while Figure 2 shows the different types of
land that have been lost.
Key Points
• Roughly 20 square miles of dry land and wetland were converted to open water along the
Atlantic coast between 1996 and 2011. (For reference, Manhattan is 33 square miles.) More of
this loss occurred in the Southeast than in the Mid-Atlantic (see Figure 1).
&EPA
Why is the Atlantic coast particularly
vulnerable to sea level rise?
Much of the land along the Atlantic coast is
flat and close to sea level—including
thousands of square miles of marshes and
other productive wetlands, plus many low-
lying cities. In addition, much of the land along
the Atlantic coast is sinking, which magnifies
the local effect of sea level rise. The land in
North America is actually still adjusting to the
loss of ice after the last ice age, which peaked
about 20,000 years ago. Back then, thick
sheets of ice covered areas of what is now
Canada and the northern United States. The
weight of all that ice depressed the land
beneath it, but caused the land farther south
(particularly the Mid-Atlantic region from
North Carolina to New York) to bulge upward.
After the ice melted and the extra weight was
lifted, northern areas began to rise, and the
Mid-Atlantic region started to sink. This very
slow process continues today.
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Climate Change Indicators in the United States: A Closer Look: Land Loss Along the
Atlantic Coast - www.epa.gov/climatechange/indicators - Updated May 2014
• The data suggest that at least half of the land lost since 1996 has been tidal wetland. The loss of
dry upland appears to be larger than the loss of non-tidal wetland. These categories account for
approximately 30 percent and 17 percent of the land lost, respectively (see Figure 2).
Figure 1. Land Loss Along the Atlantic Coast, 1996-2011
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Mid-Atlantic
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1996-2001
1996-2006
Time period
1996-2011
This graph shows the net amount of land converted to open water along the Atlantic coast during three
time periods: 1996-2001, 1996-2006, and 1996-2011. The results are divided into two regions: the
Southeast and the Mid-Atlantic (see locator map). Negative numbers show where land loss is outpaced
by the accumulation of new land.
Data source: NQAA, 20132
Southeast
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Climate Change Indicators in the United States: A Closer Look: Land Loss Along the
Atlantic Coast - www.epa.gov/climatechange/indicators - Updated May 2014
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Open water
Non-tidal wetland -*¦
Open water
| Dryland
Open water
0
1996-2001
1996-2006
Time period
1996-2011
This graph shows the net amount of land converted to open water along the Atlantic coast during three
time periods: 1996-2001, 1996-2006, and 1996-2011. The results are divided into categories to show
the type of land that has been converted to open water.
Data source: NOAA, 20133
Notes
Measurements of the change in coastal land depend on land cover and elevation data, which have
significant limits in terms of accuracy and precision. Some results are field-checked for accuracy. The
coastal land cover data are routinely compiled by the National Oceanic and Atmospheric
Administration's Coastal Change Analysis Program, and they represent the federal government's most
comprehensive set of data on land use and land cover in the coastal zone.
Sea level rise is not the only factor that contributes to the loss of coastal land. In addition to the natural
sinking of the shoreline in some areas, such as the Mid-Atlantic, coastal land loss has been made worse
by human activities such as navigation and flood control structures that block wetland migration or the
movement of sediment; withdrawal of ground water, oil, or natural gas in some regions; and boat traffic
that accelerates wetland erosion.4 Natural processes unrelated to current sea level rise can also cause
shores to erode.
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Climate Change Indicators in the United States: A Closer Look: Land Loss Along the
Atlantic Coast - www.epa.gov/climatechange/indicators - Updated May 2014
Data Sources
This feature is based on land cover data from the Coastal Change Analysis Program, which is coordinated
by the National Oceanic and Atmospheric Administration. For more information about this program,
visit: http://csc.noaa.gov/digitalcoast.
1 Crowell, M., K. Coulton, C. Johnson, J. Westcott, D. Bellomo, S. Edelman, and E. Hirsch. 2010. An estimate of the
U.S. population living in 100-year coastal flood hazard areas. J. Coastal Res. 26(2):201-211.
2 NOAA (National Oceanic and Atmospheric Administration). 2013. Coastal Change Analysis Program. Accessed
December 2013. www.csc.noaa.gov/digitalcoast/data/ccapregional.
3 NOAA (National Oceanic and Atmospheric Administration). 2013. Coastal Change Analysis Program. Accessed
December 2013. www.csc.noaa.gov/digitalcoast/data/ccapregional.
4 Titus, J.G., E.K. Anderson, D.R. Cahoon, S. Gill, R.E. Thieler, and J.S. Williams. 2009. Coastal sensitivity to sea-level
rise: A focus on the Mid-Atlantic region. U.S. Climate Change Science Program and the Subcommittee on Global
Change Research, http://librarv.globalchange.gov/products/assessments/sap-4-l-coastal-sensitivitv-to-sea-
level-rise-a-focus-on-the-mid-atlantic-region.
&EPA
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