National Parks from Coral Reefs to Wetlands to Glaciers May
Be Vulnerable to Climate Change
Special Report by Nancy C. Wilson
The following article is a condensation of a report on
Climate Change and the National Parks prepared by the Climate
Institute at the request of the National Parks and Conservation
Association.
The national parks as they exist today could be described as
"patches and tatters," protected islands in a great continental
mass. Ecologically they bear a resemblance to South Pacific atolls.
What was once an unbroken expanse across the United States of
woods, jungle and grassland, home to innumerable species of plant
and animal life has now been sliced up into industrial parks,
housing developments, farms, parking lots, malls, roads, with
here and there a nature preserve.
The threat of climate change places added stress on the remaining
preserves and parks beyond their increasing fragmentation; they
may be buffeted by sea level rise, changed rainfall patterns,
warming or aridity. As the nation makes investments in our parks,
restoring, maintaining and expanding them, we need a better understanding
of the probable impact of climate change, knowledge that we can
then factor into our forward planning. Bringing the attention
of local people to potential climate change impacts will help
them in making plans.
This report describes the threats and the gaps in our information
about the parks. It examines what steps organizations such as
the National Parks and Conservation Association can take to contribute
to improving park research and management for adaptation and mitigation
of future change.
Shifting Perspective
When Yellowstone National Park was established in parts of Montana,
Idaho and Wyoming in 1872 it was the world's first national park
and was set up - as were later additions to the national park
system -to protect what was there at the time. As understanding
of ecosystems developed in the 1960s, park management began to
shift from taking care of such special attractions as Old Faithful
to managing processes and eventually to undertaking a major research
initiative to understand, predict and detect possible effects
of global change. The "stable" communities that many of our parks
were set up to save we now know are dynamic systems composed of
many varieties of species each responding to climate in its individual
way.
Added to the perspective of continual change we get from paleoecology
(the study of fossils to determine past history), we have learned
that today's rate of climate change is unprecedented. Mountain
glaciers are shrinking, snow cover is decreasing, there is a decline
in Arctic sea ice, sea surface temperatures have increased. When
sea level rises, it floods wetlands and shrinks the marshes waterbirds
rely on. As these habi-tats decline, become more fragmented and
communities less di-verse, the rate of climate change is likely
to increase. Parks and other natural systems lose resilience,
the threat from climate impacts be-comes more acute and the environment
is more severely stressed.
Climate Change Predictions
Predictions of future climate change are imprecise, based on
General Circulation Models (GCMs). The Intergovernmental Panel
on Climate Change Second Assessment Report Synthesis, released
last December, predicts average temperatures are likely to increase
between 1 and 3.5 degrees C by the year 2100 and sea levels are
likely to rise between 15 and 95 cm. But the scale of models used
by the IPCC is too large to be use-ful for individual parks. While
the prediction of climate change is im-precise, the prediction
of ecosystem response is even more uncertain.
Climate Change Research
The fact that they were established to preserve refuges relatively
unspoiled for future generations makes the parks ideal laboratories
for long-term ecological research. They contain diverse and well-preserved
ecosystems representing each of the nation's major biogeographic
areas. Many of them have long-term data sets that can provide
an historical framework for interpreting existing conditions and
predicting future changes.
The National Park Service has been seriously concerned with climate
change research since the late 80s, when a multimillion dollar
program was launched. NPS made a major investment in the long-term
future, but the global change program has recently suffered heavy
cuts and is now concerned about how to keep support continuing.
The NPS climate change research program has been shifted to the
National Biological Service (NBS) whose continued existence is
somewhat precarious, although a national biological survey would
provide an essential database for measuring change. Some in Congress
want to abolish NBS entirely. By Congressional mandate, the NBS
will become the Biological Resources Division of USGS on October
1.
An NPS spokesman says it is difficult to maintain the integrity
of the science in the program with all the cuts and changes. The
climate change research staff would like to persuade those making
budget decisions to adopt a long range view that projections of
climate change cannot be made without long-term funding.
Because specific NBS climate change preparations have been hard
to obtain, much of the rest of this article is based on plans
started before NPS global change research was folded into NBS.
NPS "thematic" initiatives, cover the dynamics of coastal barriers
and coral reefs and overlap specific park boundaries.
Coastal Barriers
These very dynamic islands and spits stretch in an irregular
chain along the Atlantic and Gulf coasts from Maine to Texas,
protecting the whole eastern coastline from storm surges and severe
weather. Composed of sand, water and loose sediment, a shoreline
in constant flux, under the thrust of waves, currents, storm surges
and winds, the barriers encompass ecosystems of estuaries and
lagoons, which are nurseries for marine species, and also include
wetlands, open water and small sand dunes around the beaches.
The coastal plain of the East and Gulf coasts is a broad, gently
sloping surface. A small rise in sea level floods a broad band
of land. Sea level rise has averaged about one foot per century;
resulting horizontal retreat of land is at the rate of 100 to
1,000 feet per century.
With the onslaught of the sea, the barrier islands march toward
the lagoons behind and the land beyond. While sea level rise is
the driving force behind landward migration, especially during
storms, when there is overwash, it is not enough to drive barrier
beaches toward land; storm surges from hurricanes and northeasters
are the greatest movers of sand.
The barriers are very susceptible to human disturbance, and development
has increased markedly since 1960. Research by Stephen Leatherman,
Director of the University of Maryland's Coastal Research Laboratory,
and others have concluded that attempts to stabilize the highly
dynamic barrier islands will ultimately fail as sea level rises.
Success in local areas ultimately creates long-term problems.
The substantial, continuing maintenance costs incurred by even
artificial beach nourishment, the most favored alternative for
stabilization, is expensive and self-defeating. Without unlimited
funds, says Leatherman, barrier islands will continue to migrate
landward and the eventual loss of buildings should be expected
and accepted.
Barrier islands which will be affected by the above climate change
forces include parts of the following national parks:
-
Assateague Island
-
Cape Hatteras
-
Cape Lookout
-
Canaveral
-
Gulf Islands
-
Padre Island
Besides the barrier islands the park system along the coasts
includes the National Seashores such as Cape Cod and Fire Island.
The Cape Cod National Seashore, established in 1966, stretches
40 miles from Chatham to Province-town. It too is on the move;
the parking lot has been completely destroyed by overwash surges.
If sea level rises one foot in the next 50 years, the shoreline
is likely to retreat even more rapidly.
There is no active research pro-gram covering Cape Cod and the
other national seashores, another knowledge gap. The seashores
merit careful monitoring of the impacts of future climate change.
Coral Reefs
Coral-reef research is critical to understanding the impact of
global change on marine systems. Although coral reefs are among
the most stable ecosystems, during the last 10 or 15 years coral
bleaching and local extinctions have increased, and the reefs
themselves have declined in abundance. Coral-bleaching episodes
damaged reefs in Florida and the Caribbean during 1980, '83, '87
and '88 when water temperatures were high, a World Wildlife Fund
report has noted. They may be showing the effects of a one-degree
F global temperature rise over the past century.
The NPS Coral Reef Systems Thematic Initiative, covering a 200-mile
arc through the Florida keys and the Virgin Islands, has planned
studies of physiology and stress in reef-building corals to assist
in determining the predictability of future survival if sea temperature
and UV radiation increase.
The parks involved are: Biscayne National Park, Fort Jefferson
National Monument, and Virgin Islands National Park.
Glaciers
Glacier National Park, an area 175 miles by 100 miles in the
northwestern part of Montana, contains pristine examples of floral
provinces and three major watersheds converging under maritime
and continental climates. Changes in glaciers may be one of the
earliest indicators of climate change. High-elevation glaciers
in the park may be greatly reduced or disappear with increased
warming.
The elements involved are so complex and interrelated that systems
modeling is an essential component of the area's climate change
research. The goal is to predict how these dynamics will change
with a shifting climate.
Alaska is likely to be one of the first places climate changes
could be measured with confidence, according to a report of the
Alaska Research Development Project. Climate change may be most
quickly detected in fluctuations at the edge of the huge tidal
glaciers and by changes in their mass balance. The receding glaciers
would affect sea level, biodiversity, water supply and recreation.
Increased warming is expected in the winter, with spring snowmelt
earlier and spring run-off greater. More water vapor in the air
most of the time will reinforce the warming trend. The surrounding
water's ice cover would be substantially thinner and in summer
this would enhance the warming trend, as the dark ocean water
would absorb much of the solar energy now reflected by ice and
snow. While glaciers and permafrost will melt along with the sea
ice, glacial melting may be partially offset by increased snowfall
because of the greater amounts of water vapor in the air.
Warm waters will lead to changes in the location and amount of
upwelling that now feed rich fisheries, and glacial melting caused
by climate change may have tremendous impacts on subsistence fisheries
in downstream areas. Biologically important zones at the edge
of the sea would move, and we would probably see a decline in
some of the present fish population.
There is at present no NBS climate change research program studying
recession of glaciers at Glacier Bay in Alaska, an example of
a significant gap in our present knowledge gathering.
Wetlands
The U.S. has a very large area of wetlands - 32,330 km2 - 1.6
percent of the country's total area. (Only Southeast Asia, the
Caribbean and the large islands of the Pacific Ocean have larger
percentages.) The two large wetlands in the National Park System,
the Everglades National Park and Big Cypress National Preserve
in south Florida, and the Big Thicket National Preserve in the
Gulf Coastal Plain, contain an array of flora and fauna under
threat of global change.
The Everglades, a broad freshwater marsh only a few meters above
sea level, is maintained by runoff from the interior of the state;
saltwater wetlands on its edges are dominated by mangrove swamps
which are limited by the range of tides. NPS research in the South
Florida Biogeographic Area has focused on the global change impact
on the mangrove system including, besides the effects of sea level
rise, increased storm frequency and intensity, changing temperature
and increased variability of other climatic factors. The devastation
in the Everglades from Hurricane Andrew in 1992 is a sober warning
of what may happen if climate change brings frequent or more intense
storms.
Mangrove colonies probably could not shift inland fast enough
to keep up with rising sea levels and would be killed, according
to a 1992 World Wildlife Fund report, eliminating ecosystems that
are among the world's most productive fish hatcheries. Salt water
might inundate freshwater areas and land near sea level.
The growing population on the fringes of the Everglades ecosystem
depends on water from the inland freshwater. The area's six million
residents - a number that has doubled in 20 years and may triple
in the next 50 - are likely to be there to stay. Global-change
re-search may help determine how to manage the fragile relationship
between humans and nature in this environment.
Climate Change Impacts
The recently released assessment of climate change impacts by
the Intergovernmental Panel on Climate Change lists ways the assessment
has been improved in the past five years by:
-
adding the effects of sulphate aerosols to models.
-
making simulations of coupled atmospheric-ocean models more
complete,
-
shifting the focus from global mean changes to modeled and
observed patterns to allow for more precise consideration,
for example, of the fact that climate change in high latitudes
may be more extreme than in the tropics.
-
An increase in the intensity of precipitation and a possibility
of more extreme rainfall events
These improvements have bettered the GCMs' fit and given the
assessment authors the confidence to state that climate change
shows "a discernible human influence."
Climate Change Science
-
In winter at the Earth's surface, greater warming of land
than sea
-
Maximum surface warming in high northern latitudes in winter;
little surface warming over Arctic in summer
-
Changes in total precipitation and its frequency and intensity
will affect the magnitude and timing of runoff, although specific
regional effects are uncertain.
-
Increased precipitation and soil moisture in high latitudes
in winter
-
Decreased strength of North Atlantic ocean circulation which
depends on the joint effects of temperature and salinity,
and widespread decrease in daytime range of temperature
-
Inclusion of aerosol effects will lead to smaller estimated
magnitudes of temperature and precipitation changes. The distribution
of aerosols is expected to have a strong influence on estimated
regional projections
-
General warming is expected to lead to an increase in the
occurrence of extremely hot days and a decrease in the occurrence
of extremely cold days
-
Warmer temperatures are projected to lead to a more vigorous
hydrological cycle, bringing prospects for changes in droughts
and floods which may be more severe in some places, less severe
in others
-
An increase in the intensity of precipitation and a possibility
of more extreme rainfall events
-
There is still not enough knowledge to predict changes in
the occurence or geograpical distribution of severe storms
such as tropical cyclones
Source: IPCC WG I, Summary for Policymakers,The Science of
Climate Change, 1995
Table: Potentially Bewildering Impacts
Forests A one degree C increase in global temperature
affects the growth and capacity to regenerate of forests in many
regions, in some cases altering the composition significantly.
One-third of existing forested area of the world will undergo
major changes in broad types of vegetation, affecting the rate
of speed at which forest species grow, reproduce and reestablish
themselves. The greatest changes will occur at high latitudes,
least in the tropics. Entire forests may disappear; new ecosystems
may be established. Outbreaks of disease will be more frequent;
the ranges of pests and pathogens will be extended. Fires will
be more frequent and intense. The amount of rainfall will change
and the season in which it falls may shift, leading to increased
evaporation from the soil and transpiration from plants. Shifts
in temperature and precipitation in temperate rangelands may lead
to altered growing seasons and in boundary shifts between grasslands,
forest and shrublands.
Deserts are likely to become hotter but not wetter.
Temperature increases will pose a threat to organisms which are
near their heat tolerance limits. Desertification is likely to
become more irreversible.
Cryosphere One-third to one-half of mountain glaciers
could disappear in the next 100 years, affecting river flow. A
decrease in sea-ice could lead to longer navigation seasons on
rivers and in the Arctic. Other Arctic changes include a decrease
in glaciers, permafrost and snow cover.
Mountain Ranges Similar changes in mountain ranges
will affect the surface, ground and atmospheric circulation of
water and the stability of the soil. Species limited to mountain
tops could disappear. Recreational industries are likely to be
disrupted.
Lakes, streams and wetlands could have altered
water temperatures, flow and water levels. Biological activity
could increase at high latitudes, while at low latitudes cold
and cool water species would suffer the greatest harm.
Coastal systems would have varied responses:
a rise in sea level or change in storms or storm surges would
lead to shore erosion and change in habitat, increased salinity
of estuaries and freshwater aquifers, altered tide ranges in rivers
and bays, changes in sediment and nutrient transport, change in
the pattern of chemical and microbiological contamination in coastal
areas and increased coastal flooding
particularly at risk would be: saltwater marshes, mangrove ecosystems,
coastal wetlands, coral atolls and river deltas
major negative effects would be on tourism, fisheries, biodiversity
effects would add to modification in the functioning of coastal
oceans and inland waters that already have resulted from pollution
and physical changes
coastal populations would be increasingly vulnerable to flooding
and the loss of land by erosion
Oceans The effect of climate change on oceans would
lead to a change in sea level, altered circulation, vertical mixing,
wave climate and a decrease in sea-ice cover. This would have
a major impact on fisheries. It is possible an abrupt climate
change itself would result if freshwater influx from melting sea
ice or ice sheets significantly weaken ocean global circulation
which depends on connections between temperature and salinity.
Source: IPCC WG II, Summary for Policymakers,Scientific-Technical
Analyses of Impacts, Adaptations, and Mitigation of Climate Change,
1995
Implications
Our nature reserves face the combination of different rates of
migration, extinction and unpredictable interactions from both
climate change and destroyed habitat. Our lack of understanding
of the structure and function of ecosystems and how they interact
with changing climate limits our ability to predict the consequences
of human-induced climate change on species and communities.
It is very difficult for parks to perpetuate communities and
species today. The ability of species to adapt depends not only
on genetics but also on capacity to disperse and migrate. It is
often difficult to predict how long it will take for a species
to respond to climate change by colonizing new areas. A species
may be protected by a specially created preserve, but limits in
the range of the species may still doom it. The Kirtland's warbler
depends for nesting solely on certain young jack pine forests
in the lower peninsula of Michigan. Turning these forests into
a preserve cannot save the warbler if climate change leads to
the replacement of the jack pines by white pine and red maple.
While the rates of climate change are expected to exceed any that
present flora and fauna have ever experienced, the actual impacts
are largely unknown. Some change will be adverse, some beneficial.
Some climate-induced environmental changes cannot be quickly reversed;
some are irreversible.
The faster the rate of climate change, the higher the probability
of disruption of the ecosystem, the greater the risk of surprise,
and the greater the risk of serious ecosystem degradation. As
ecosystems will not move in one piece, with each species reacting
differently, species associations will break up and new communities
form. The response will depend on competition among species to
maintain themselves in new areas or under changing conditions.
Natural disturbances like hurricanes and fires are not only likely
to occur but are sometimes the inevitable result of climate change.
And some like wildfires in certain areas may be critical elements
in the sustained functioning of ecosystems.
Besides climate, many non-climate influences stress ecosystems
and the projections of their interaction do not always follow
a straight line. Most projections are based on an arbitrary assumption
of a doubling of CO2; few have considered dynamic responses to
steadily increasing concentrations of greenhouse gases or have
assessed the implications of a combination of stress factors.
Managing Our Parks
In view of the continual shifts and interactions, Adam Markham
of the World Wildlife Fund suggests a gradual shift in priorities
from species-based conservation to an approach based on whole
ecosystems.
Conclusion
A preliminary look at the current status of our parks based on
the primitive knowledge we have suggests they have a high degree
of vulnerability. Sea level rise will endanger our coasts - the
barrier islands, beaches and wetlands. Higher temperatures may
melt glaciers; changing patterns of storms and hurricanes may
increase the likelihood of droughts and floods. The impacts on
habitats could be devastating. A change in soil moisture would
harm trees and plants, and forests may be unable to migrate fast
enough to adapt to new conditions. There is increasing landscape
fragmentation.
Assessing regional and local impacts of climate change requires
much more detail than the complex information used in the GCMs
of the IPCC and other operators of world climate models. The databases
are orders of magnitude greater, and it is here that our greatest
knowledge gaps exist. We need radically improved models to predict
regional climate change and to quantify threats to biodiversity
and conservation on a local scale. We need higher resolution models
that deal better with annual rainfall both during the year and
between years, with sea-sonal changes and with extreme events
- especially drought -to improve our ability to assess eco-system
vulnerability to climate change.
The data gathering and model development present a daunting proposition,
requiring cooperation of local and regional institutions and agencies
- both government, academic and private - to satisfy the needs
of local and regional decisions makers. We need to persuade those
setting funding policies to adopt a longer range view and to realize
that we cannot make long-term projections without longer range
funding.
Although good research programs have been started, their low
status among national priorities combined with Federal budget
cutbacks have left us without a very good handle on what impact
climate change is likely to have or what future dangers impend.
Many gaps exist in our knowledge. Although we understand in general
that loss of diversity and complexity diminishes the stability
of ecosystems, we rarely know enough to predict how the loss of
a particular species will affect the capacity of a particular
system to resist or recover from disturbance. More monitoring
and research should help to clear up some of this uncertainty.
In quantifying ecological limits to climate change, we need to
identify key areas for concentrating biodiversity and conservation
efforts. Nevertheless, uncertainty about climate change and the
rate at which it is happening is no excuse for inaction.
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