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 Climate
Impacts in the U.S. Islands
Overview
The U.S. tropical islands include Puerto Rico and the U.S.
Virgin Islands in the Caribbean, and Hawai’i, Guam, the
Northern Mariana Islands, and American Samoa in the Pacific.
Many islands are especially vulnerable to the risks of
climate change because of their small size, low elevation,
remote geographical location, and concentration of
infrastructure along coastlines. Islands are also home to
unique ecosystems, including coral reefs, mangrove forests,
and diverse populations of native species found nowhere else
in the world. Island ecosystems are already stressed from
human development and pollution, making them particularly
sensitive to additional stresses from climate change.
Islands are experiencing rising air temperatures and sea
levels, and warmer, more acidic coastal waters. Temperatures
are expected to increase into the future, but will vary in
the extent of warming that occurs based on location,
elevation, and changes in ocean conditions. In Hawai’i and
the Central North Pacific, temperatures are projected to
rise by 1.5°F to 3.5°F by mid-century, while in Guam and
Northern Mariana Islands, increases of 1.9°F to 2.6°F are
projected.[1] In the Caribbean, Puerto Rico is projected to
warm by 2°F to 5°F by the end of this century.
Changes in precipitation are also being observed. The
Pacific Islands are highly influenced by El Niño and La Niña
events, which create annual variability in storms and
precipitation. Despite this variability, a trend for
decreasing precipitation has been observed in Hawai’i, while
a small increase has been measured in the Northern Mariana
Islands and in Guam. Future precipitation patterns are less
certain, but for Hawai’i, projections suggest a small
decrease in precipitation during the wet season and a small
increase during the dry season. Some parts of the Caribbean
are experiencing reduced precipitation while other areas are
have seen increases. Continued variation in trends is
expected in the future, but on average, precipitation is
expected to decrease across the Caribbean. In Puerto Rico,
an increasing amount of rain has been falling in the form of
heavy downpours in recent history. Limited information for
American Samoa shows no significant change in precipitation. |
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 Water
Resources
Climate change is expected to affect the availability of
water on some islands, particularly on small islands and
atolls. On islands where precipitation decreases, ground and
surface water supplies may not be recharged, resulting in
less freshwater availability. This can impact both drinking
water supplies and irrigation water for crops. Sea level
rise and coastal erosion may also reduce water availability
by inundating land with saltwater, contaminating freshwater,
and preventing recharge of the freshwater supply. Increased
temperatures coinciding with reduced precipitation are also
expected to increase the likelihood of drought.
Picture - Freshwater
Lens: Many island communities rely on freshwater lenses,
especially for irrigation. Freshwater lenses form when
freshwater enters aquifers and floats on top of saltwater,
which is much more dense. The amount of water contained in a
freshwater lens is determined by the size of the island, the
amount of rainfall, water withdrawal, the permeability of
the rock beneath the island, and mixing with saltwater.
These lenses can be as shallow as a few inches or as deep as
65 feet. Credit: USGCRP (2009) (196 pp, 13 MB, About PDF)
In contrast, some islands are expected to receive heavier
downpours, which can cause flooding, overload water
infrastructure systems, and result in sewage contamination
and public health concerns. On islands where populations are
growing or where infrastructure is old or poorly maintained,
the impacts on water supplies may be especially severe.
For more information about climate change impacts on water,
please visit the Water Resources page. |
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 Communities
and Agriculture
Climate change will have far-reaching effects on local
island culture, health, and livelihoods, altering
traditional lifestyles on the islands. Cultural structures
may be lost to rising seas while availability of traditional
foods may decline because of coral reef losses, drought, or
saltwater inundation of agricultural lands. Residents in
coastal areas may need to relocate if climate-related
damages become too extreme. For more information about
climate change impacts on culture, please visit the Society
page.
Picture - Saltwater
inundation caused by storm surges or very high tides can
kill important agricultural crops. This taro crop requires
2-3 years of growth before harvest. After inundation, it can
take 2 years for the salt to be flushed from the soils to
allow replanting. Credit: USGCRP (2014)
Climate change is also expected to negatively impact human
health. The incidence of some diseases, such as dengue
fever, are likely to increase in the Pacific Islands. In the
Caribbean, diseases already present, including malaria and
dengue and yellow fevers, could increase with warming
temperatures.
Coastal agriculture is also affected by climate change. Sea
level rise can lead to saltwater inundation, causing soils
to become saltier and less fertile on some islands. Water
supplies can suffer as a result of reductions in rainfall or
from saltwater intrusion, reducing both drinking water and
irrigation water availability.
For more information about climate change impacts on
agriculture and food, please visit the Agriculture and Food
Impacts page. |
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 Infrastructure
and Economy
Island infrastructure and economic development are at
greater risk due to climate change. Island settlements,
social and leisure events, and economic activity tend to be
concentrated close to the coasts, especially on smaller
islands. This makes them especially vulnerable to climate
change impacts from sea level rise, coastal inundation,
storm surge, flooding, and shoreline erosion.
Picture - Coastal
houses and an airport in the U.S.-affiliated Federated
States of Micronesia rely on mangroves' protection from
erosion and damage due to rising sea level, waves, storm
surges, and wind. Credit: USGCRP (2009) (196 pp, 13 MB,
About PDF)
Higher sea levels, inundation, flooding, and shoreline and
beach erosion are expected to affect critical
transportation, energy, and water infrastructure, including
airports, roads, ports, and wastewater systems. Because of
their geographic remoteness, islands largely rely on
imported food, fuel, and materials, making damage to
airports or ports especially critical to the well-being of
island residents. The impacts of sea level rise are already
being felt. In Rincón, Puerto Rico, sea level rise is
currently eroding the coastline at a rate of about three
feet per year.
Climate change will affect tourism, an important source of
revenue for islands. Sea level rise, warming water
temperatures, increasing storm intensity, beach erosion, and
ocean acidification could pose risks to beaches and threaten
coastal activities, such as coral reef exploration, boating,
and fishing. Closures to island beaches due to damage or
harmful algal blooms could have large economic impacts,
particularly on the tourism sector. In Puerto Rico, 3.5
million tourists spent $3.5 billion in 2009. Tourism
accounts for 26% of the state income in Hawai’i. The loss of
the Waikiki Beach in Hawai’i alone could reduce the state
annual income by $2 billion. |
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 Ecosystems
Islands are home to unique ecosystems and species that
provide economic opportunities, safety, and cultural value
to island communities. Rising sea levels, temperatures, and
ocean acidification of coastal waters are threatening the
stability and functioning of these ecosystems.
Picture - Climate
change is increasing the temperature and acidity of the
world’s oceans. These changes threaten the health and
survival of coral reef ecosystems. Credit: USGCRP (2014)
Coral reefs serve as an important habitat for many fish and
marine organisms. They also provide shoreline protection,
valuable fisheries, and revenue through tourism. In Hawai’i,
the goods and services provided by coral reefs are estimated
to bring in approximately $385 million each year. In the
Caribbean, income losses associated with degraded reefs are
conservatively estimated to be several hundred million
dollars each year.
Reef ecosystems are stressed by coastal development,
pollution, and invasive species. Warmer, more acidic coastal
waters further stress reefs, and coral disease outbreaks and
bleaching events tend to coincide with warming waters. As
the oceans warm, coral cover is expected to decline greatly.
Oceans are also becoming more acidic. This occurs as the
higher levels of carbon dioxide in the atmosphere react with
sea water to produce carbonic acid. Since the Industrial
Revolution, ocean acidity has increased by 30%, a rate that
is approximately 50 times faster than the known historical
change prior to this period. Acidity is projected to
increase by an additional 37% to 50% above present levels by
the end of the century.
Increases in ocean acidity (measured by lower pH values)
changes the balance of minerals in the water. This change
makes it more difficult for corals, some types of plankton,
and other organisms to produce calcium carbonate, which
makes up and strengthens the marine organisms’ hard
skeletons and shells. |
 As
climate change alters coral reefs, reduction in fish
populations that inhabit these ecosystems is expected. Many
island communities depend on local fisheries for survival
and economic development. Changes in ocean temperatures can
also damage fish habitats and cause shifts in the
reproduction or migration behaviors of certain fish species,
including tuna. These impacts may exacerbate existing
stresses on fisheries, such as those from pollution and
overfishing, and may ultimately lead to a decline in the
abundance and health of fishery populations.
Picture - As carbon
dioxide levels increase in the atmosphere, more carbon
dioxide dissolves into the oceans and forms carbonic acid.
As this occurs, the pH decreases (increasing acidity). This
pattern has been observed near numerous islands, including
Hawai’i. Source: US EPA (2015)
Sea level rise will result in flooding or loss of tidal
marshes, swamps, and other coastal habitats. These
ecosystems provide important habitat for birds and aquatic
organisms, and losses will exacerbate existing stresses on
vulnerable species. In the Caribbean, forests are retreating
from the coastlines. Mangrove forests, which help to protect
shorelines, are expanding in some parts of the Caribbean,
but are shrinking in parts of the Pacific.
Plants and animals are increasingly stressed by high
temperatures and, on some islands, reduced rainfall.
High-elevation ecosystems are especially vulnerable because
they have limited ability to find suitable habitat. Climate
change is also providing conditions that increase the spread
of invasive species, pathogens, and diseases, which will
affect populations of native plants, birds, and freshwater
organisms.
For more information about climate change impacts on
ecosystems, please visit the Ecosystems Impacts page. |
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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
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comment. Thanks. |
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Key Points
Warmer and more acidic oceans are adding to existing
stresses on coral reefs and fish communities.
Sea level rise is expected to threaten the water supplies,
ecosystems, and infrastructure of U.S. tropical islands.
Climate change is likely to affect livelihoods, as well as
tourism and other important economic sectors on tropical
islands. |
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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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