The Florida Everglades and
Sea-Level Rise
Reconstructed satellite images show
the Everglades of the
1850s (left) and
present day (right). The yellow lines are
the
historical and current border of the
Everglades ecosystem.
Image courtesy of the South Florida Water Management
District.Visitors to Everglades National Park come to marvel at
vast swamps that are home to wading birds, alligators,
wood storks, Florida panthers, and manatees. But the
region known as the Everglades has undergone dramatic
changes over the past 100 years, shrinking to half its
original size. These changes are primarily the result of
human manipulation and pollution of the region's most
critical resource—water. There are ongoing efforts to
restore the ecosystem, but increasing water temperatures,
changes in precipitation, and more extreme storms will
likely make restoration more difficult.
One major change that could affect the Everglades
and other unique ecosystems is sea-level rise. Sealevel
rise can increase the salt content of existing
bodies of fresh water and could cause existing dry
ecosystems to find themselves under water by the end
of this century. Some regions of the Gulf Coast are simultaneously being affected by sea-level
rise and subsidence, or sinking, of the land. In these areas, the water level is projected to rise
2–4 feet over this century—reconfiguring shorelines and fragmenting barrier islands.
Some mangroves and marshes—two
types of plant community specially
adapted to the conditions at the borders
between land and sea—are moving
inland in response to sea-level
rise. Unfortunately, roads and buildings
in highly developed areas make
this adaptation strategy more difficult.
Additionally, a rapid rate of future
climate change would leave many
mangroves and marshes hard-pressed
to move fast enough to compensate
for those that are lost to the sea.
Coral Reefs
The coral reefs of Biscayne National Park, just miles
from downtown Miami, Florida, attract more
than half a million visitors per year. In addition
to drawing crowds for their dazzling natural
beauty, coral reefs play some important roles in
the marine ecosystem. For example, they provide
key habitat for fish and act as a protective barrier
for nearby shores. Unfortunately, overfishing,
pollution, and coastal development are already
degrading reefs off the Florida Keys and in other tropical
U.S. waters. Climate and associated changes pose
an increasing threat to their survival.
A partially
bleached coral.
Image from
NOAA.The shallow tropical waters in which most corals are found are warming. Heat stress causes
corals to expel the symbiotic algae that provide their primary source of nutrition, leaving only
the white "bones" of the corals behind. This process, called coral bleaching, can be lethal to
the coral if it lasts too long. Coral bleaching, which has increased in recent decades, becomes
worse as high temperatures last longer and longer.
Corals are also being affected by ocean acidification, which is caused by the increase in carbon
dioxide in the atmosphere. This affects the ability of marine organisms to build their shells and
skeletons. Ocean acidification is likely to slow, or even stop, the growth of coral over this century.
This would not only affect the corals themselves but also put in jeopardy the survival of the
myriad species found only on coral reefs.
Northward Movement of
Tropical Species
Rufous Hummingbird. Image courtesy of Dean
E. Briggins, U.S. Fish and Wildlife Service.Tropical species are moving northward into the southern
United States, delighting bird and butterfly watchers alike.
Former migrants like the rufous hummingbird and the
Mexican green jay have become year-round residents in
Alabama and Texas, respectively. Florida has five new species
of tropical dragonfly, and many tropical butterflies normally
confined to Mexico are starting to breed as far north
as Austin, Texas.
This web page is based on the National Academies' educational booklet
Ecological Impacts of Climate Change.
