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 Climate
Impacts on Coastal Areas
Overview
The coastline of the United States is highly populated.
Approximately 25 million people live in an area vulnerable
to coastal flooding. Coastal and ocean activities, such as
marine transportation of goods, offshore energy drilling,
resource extraction, fish cultivation, recreation, and
tourism are integral to the nation's economy, generating 58%
of the national gross domestic product (GDP). Coastal areas
are also home to species and habitats that provide many
benefits to society and natural ecosystems. |
 Climate
change can affect coastal areas in a variety of ways. Coasts
are sensitive to sea level rise, changes in the frequency
and intensity of storms, increases in precipitation, and
warmer ocean temperatures. In addition, rising atmospheric
concentrations of carbon dioxide (CO2) are causing the
oceans to absorb more of the gas and become more acidic.
This rising acidity can have significant impacts on coastal
and marine ecosystems.
Picture - The National
Oceanic and Atmospheric Administration (NOAA) projects that
sea level rise will increase flooding in Charleston, South
Carolina. Source: NOAA Coastal Services Center (2012)
The impacts of climate change are likely to worsen problems
that coastal areas already face. Confronting existing
challenges that affect man-made infrastructure and coastal
ecosystems, such as shoreline erosion, coastal flooding, and
water pollution, is already a concern in many areas.
Addressing the additional stress of climate change may
require new approaches to managing land, water, waste, and
ecosystems. |
|
 Sea
Level Rise
Since 1901, global sea level has risen approximately eight
inches.
In a particular location, the change in sea level that is
observed will be affected by the increase in global sea
level as well as land movement up or down. The motion of
land can be caused by subsiding coastal lands, oil and water
extraction activities, melting ice, or tectonic movement.
The terms "local" or "relative" sea level refer to both the
global change in sea level and the effects of land motion.
Picture - Observed
changes in sea level relative to land elevation in the
United States between 1960 and 2014. Source: EPA (2015)
Where the land is sinking, the rate of relative sea level
rise is larger than the global rate. Some of the fastest
rates of relative sea level rise in the United States are
occurring in areas where the land is sinking, including
parts of the Gulf Coast. For example, coastal Louisiana has
seen its relative sea level rise by eight inches or more in
the last 50 years, which is about twice the global rate.
Subsiding land in the Chesapeake Bay area worsens the
effects of relative sea level rise, increasing the risk of
flooding in cities, inhabited islands, and tidal wetlands. |
 Mostly
because of these differences in land motion, estimates of
future relative sea level rise vary for different regions.
Climate change models project that global sea level rise
will accelerate in the 21st century. Models based on thermal
expansion and ice melt estimate that global sea level is
very likely to rise between 1 and 3 feet by the end of the
century. Typically, these models do not, however,
incorporate all of the possible responses of ice sheets to
warmer temperatures, which could further raise sea level,
but is unlikely to add more than one foot. For more
information on recent and future sea level rise, please
visit the Science section.
Picture - Sea Level
Rise and Coastal Flooding Impacts Viewer
The National Oceanic and Atmospheric Administration has
developed a tool to visualize the potential impacts of sea
level rise on coastal communities in the United States.
NOAA's sea level rise and coastal flooding impacts viewer.
Source: NOAA (2012)
Growing populations and development along the coasts
increase the vulnerability of coastal ecosystems to sea
level rise. Development can block the inland migration of
wetlands in response of sea level rise, and change the
amount of sediment delivered to coastal areas and accelerate
erosion. For example, coastal Louisiana lost approximately
2000 square miles of wetlands in recent decades due to human
alterations of the Mississippi River's sediment system and
oil and water extraction that has caused land to sink. As a
result of these changes, wetlands do not receive enough
sediment to keep up with rising seas, and may no longer
function as natural buffers to flooding.
Rising sea level also increases the salinity of ground water
and pushes salt water further upstream. Higher salinity can
make water undrinkable without desalination, and harms many
aquatic plants and animals.
Impacts of Changes in Storm Surge
and Precipitation
Coastal areas are also vulnerable to increases in the
intensity of storm surge and heavy precipitation. Storm
surges flood low-lying areas, damage property, disrupt
transportation systems, destroy habitat, and threaten human
health and safety. For example, low-lying areas of New York
City, Long Island, and New Jersey were flooded by several
feet of water by the storm surge from Superstorm Sandy in
2012. Sea level rise could magnify the impacts of storms by
raising the base on which storm surges build.
Climate change is likely to bring heavier rainfall to some
coastal areas, which would also increase runoff and
flooding. In addition, warmer temperatures in mountain areas
could lead to more spring runoff due to melting of snow. In
turn, increases in spring runoff may also threaten the
health and quality of coastal waters. Some coastal areas,
such as the Gulf of Mexico and Chesapeake Bay, are already
experiencing "dead zones." Dead zones occur when land-based
sources of pollution (e.g., agricultural fertilizers)
contribute to algal blooms. When the algae sink and
decompose, the process depletes the oxygen in the water. As
increases in spring runoff bring more nitrogen, phosphorus,
and other pollutants into coastal waters, many aquatic
species could be threatened.
Decreases in precipitation could also increase the salinity
of coastal waters. Droughts reduce fresh water input into
tidal rivers and bays, which raises salinity in estuaries,
and enables salt water to mix further upstream.
Impacts of Coastal Water Temperature
Coastal waters have warmed during the last century, and are
very likely to continue to warm in the 21st century,
potentially by as much as 4 to 8°F. This warming may lead to
big changes in coastal ecosystems, affecting species that
inhabit these areas.
Warming coastal waters cause suitable habitats of
temperature-sensitive species to shift poleward. Some areas
have recently seen range shifts in both warm- and cold-water
fish and other marine species. Pollock, halibut, rock sole,
and snow crab in Alaska and mangrove trees in Florida are a
few of the species whose habitats have already begun to
shift. Suitable habitats of other species may also shift,
because they cannot compete for limited resources with the
southern species that are moving northward.
For more information on climate change impacts on species,
visit the Ecosystems page. |
|
 Impacts
to Coral Reefs and Shellfish
Higher sea surface temperatures increase the risks of coral
bleaching, which can lead to coral death and the loss of
critical habitat for other species. The rising concentration
of carbon dioxide (CO2) in the atmosphere has increased the
absorption of CO2 in the ocean, which subsequently makes the
oceans more acidic. This trend is very likely to continue in
the coming decades. A more acidic ocean adversely affects
the health of many marine species, including plankton,
mollusks, and other shellfish. In particular, corals can be
very sensitive to rising acidity, as it is difficult for
them to create and maintain the skeletal structures needed
for their support and protection. Corals in the Florida
Keys, Hawaii, Puerto Rico, and other U.S. territories are
likely to experience substantial losses if CO2
concentrations in the atmosphere continue to rise at their
current rate.
Picture - Bleached
brain coral. Source: NOAA |
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EPA Page |
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This is the
EPA page for this topic. To see if the Trump
administration has changed the EPA page, simply click the
link and compare the information with this page. If you
notice changes were made to the EPA page, please post a
comment. Thanks. |
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Key Points
Climate change threatens coastal areas, which are already
stressed by human activity, pollution, invasive species, and
storms.
Sea level rise could erode and inundate coastal ecosystems
and eliminate wetlands.
Warmer and more acidic oceans are likely to disrupt coastal
and marine ecosystems.
Coastal development reduces the ability of natural systems
to respond to climate changes.
Climate Ready Estuaries Program
Estuaries are particularly sensitive to many projected
impacts of climate change, including erosion from rising
seas, changes in storms frequency and intensity, and the
amount of precipitation. EPA's Climate Ready Estuaries
program works with National Estuary Programs and other
coastal managers to:
Assess climate change vulnerabilities.
Engage and educate stakeholders.
Develop and implement adaptation strategies.
Share lessons learned with other coastal managers.
The Climate Ready Estuaries website provides resources for
estuaries and coastal programs that are interested in
learning more about climate change impacts and adaptation.
To learn more about estuaries, visit the National Estuaries
Program web page. |
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Additional Climate Change Information |
Climate Change and Carbon Dioxide
(Beginner - Listening,
reading)
A video lesson to
help with your understanding of climate change
and carbon dioxide.
The English is
spoken at 75% of normal speed.
Great English listening and reading practice. |
Carbon Dioxide and Climate Change
(Beginner - Listening,
reading)
A video lesson to
help with your understanding of carbon dioxide
and climate change.
The English is
spoken at 75% of normal speed.
Great English listening and reading practice. |
Environmental Group Warns Earth's Health at Risk
(Beginner - Listening,
reading)
A video lesson to
help with your understanding of climate change.
The English is
spoken at 75% of normal speed.
Great English listening and reading practice.
A report by the World Wildlife Fund looked at thousands of animal populations
and found they have dropped significantly in 40 years. |
Sea Levels Rising at Fastest Rate in 3,000 years
(Beginner - Listening,
reading)
A video lesson to
help with your understanding of climate change.
The English is
spoken at 75% of normal speed.
Great English listening and reading practice.
A group of scientists say sea levels are rising at record rates. Another group
found that January temperatures in the Arctic reached a record high. |
Capturing CO2 Gas Is Not Easy
(Beginner - Listening,
reading)
A video lesson to
help with your understanding of climate change.
The English is
spoken at 75% of normal speed.
Great English listening and reading practice.
Most scientists agree that carbon-dioxide gas is partly to blame for climate
change: rising global temperatures. But capturing the CO2 gas released by power
stations is costly and difficult. |
Growth, Climate Change Threaten African Plants and
Animals
(Beginner - Listening,
reading)
A video lesson to
help with your understanding of climate change.
The English is
spoken at 75% of normal speed.
Great English listening and reading practice.
Researchers believe Africa may lose as much as 30 percent of its animal and
plant species by the end of this century. |
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