United States
Environmental Protection
Agency
Office of Policy, Planning
and Evaluation
(2111)
EPA 230-F-97-008dd
September 1997
&EPA Climate Change And New Jersey
The earth's climate is predicted to change because human
activities are altering the chemical composition of the atmosphere
through the buildup of greenhouse gases — primarily carbon
dioxide, methane, nitrous oxide, and chlorofluorocarbons. The
heat-trapping property of these greenhouse gases is undisputed.
Although there is uncertainty about exactly how and when the
earth's climate will respond to enhanced concentrations of
greenhouse gases, observations indicate that detectable changes
are under way. There most likely will be increases in temperature
and changes in precipitation, soil moisture, and sea level, which
could have adverse effects on many ecological systems, as well
as on human health and the economy.
The Climate System
Energy from the sun drives the earth's weather and climate.
Atmospheric greenhouse gases (water vapor, carbon dioxide.
and other gases) trap some of the energy from the sun, creating
a natural "greenhouse effect." Without this effect, temperatures
would be much lower than they are now, and life as known today
would not be possible. Instead, thanks to greenhouse gases, the
earth's average temperature is a more hospitable 60°F. However.
problems arise when the greenhouse effect is enhancedby
human-generated emissions of greenhouse gases.
Global warming would do more than add a few degrees to today's
average temperatures. Cold spells still would occur in winter, but
heat waves would be more common. Some places would be drier.
others wetter. Perhaps more important, more precipitation may
come in short, intense bursts (e.g., more than 2 inches of rain
in a day), which could lead to more flooding. Sea levels would
be higher than they would have been without global warming.
although the actual changes may vary from place to place because
coastal lands are themselves sinking or rising.
The Greenhouse Effect
Some solar radiation
is reflected by the
earth and the
L atmosphere
Some of the infrared radiation passes
through the atmosphere, and some is
absorbed and re-emitted in all
directions by greenhouse gas
molecules. The effect of this is to warm
the earth's surface and the lower
atmosphere.
Source: U.S. Department of State (1992)
Emissions Of Greenhouse Gases
Since the beginning of the industrial revolution, human activities
have been adding measurably to natural background levels of
greenhouse gases. The burning of fossil fuels — coal, oil, and
natural gas — for energy is the primary source of emissions.
Energy burned to run cars and trucks, heat homes and businesses.
and power factories is responsible for about 80% of global
carbon dioxide emissions, about 25% of U.S. methane emissions.
and about 20% of global nitrous oxide emissions. Increased
agriculture and deforestation, landfills, and industrial production
and mining also contribute a significant share of emissions. In
1994, the United States emitted about one-fifth of total global
greenhouse gases.
Concentrations Of Greenhouse Gases
Since the pre-industrial era, atmospheric concentrations of carbon
dioxide have increased nearly 30%, methane concentrations have
more than doubled, and nitrous oxide concentrations have risen
by about 15%. These increases have enhanced the heat-trapping
capability of the earth's atmosphere. Sulfate aerosols, a common
air pollutant, cool the atmosphere by reflecting incoming solar
radiation. However, sulfates are short-lived and vary regionally.
so they do not offset greenhouse gas warming.
Although many greenhouse gases already are present in the
atmosphere, oceans, and vegetation, their concentrations in the
future will depend in part on present and future emissions.
Estimating future emissions is difficult, because they will depend
on demographic, economic, technological, policy, and institu-
tional developments. Several emissions scenarios have been
developed based on differing projections of these underlying
factors. For example, by 2100, in the absence of emissions
control policies, carbon dioxide concentrations are projected to
be 30-150% higher than today's levels.
Current Climatic Changes
Global mean surface temperatures have increased 0.6-1.2°F since
the late 19th century. The 9 warmest years in this century all have
occurred in the last 14 years.
Several pieces of additional evidence consistent with warming.
such as a decrease in Northern Hemisphere snow cover, a
decrease in Arctic Sea ice, and continued melting of alpine
glaciers, have been corroborated. Globally, sea levels have risen
4-10 inches over the past century, and precipitation over land has
increased slightly. The frequency of extreme rainfall events also
has increased throughout much of the United States.
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Global Temperature Changes (1861-1996)
Year
Source: IPCC (1995), updated
A new international scientific assessment by the Intergovern-
mental Panel on Climate Change recently concluded that "the
balance of evidence suggests a discernible human influence
on global climate."
Future Climatic Changes
For a given concentration of greenhouse gases, the resulting
increase in the atmosphere's heat-trapping ability can be pre-
dicted with precision, but the resulting impact on climate is more
uncertain. The climate system is complex and dynamic, with
constant interaction between the atmosphere, land, ice, and
oceans. Further, humans have never experienced such a rapid rise
in greenhouse gases. In effect, a large and uncontrolled planet-
wide experiment is being conducted.
General circulation models are complex computer simulations
that describe the circulation of air and ocean currents and how
energy is transported within the climate system. While uncertain-
ties remain, these models are a powerful tool for studying
climate. Scientists are reasonably confident about the ability of
models to characterize future climate at continental scales.
Recent model calculations suggest that the global surface temper-
ature could increase an average of 1.6-6.3°F by 2100, with signif-
icant regional variation. These temperature changes would be far
greater than recent natural fluctuations, and they would occur
significantly faster than any known changes in the last 10,000
years. The United States is projected to warm more than the
global average, especially as fewer sulfate aerosols are produced.
The models suggest that the rate of evaporation will increase as
the climate warms, which will increase average global precipita-
tion. They also suggest increased frequency of intense rainfall as
well as a marked decrease in soil moisture over some mid-
continental regions during the summer. Sea level is projected to
increase by 6-38 inches by 2100.
Calculations of regional climate change are much less reliable
than global ones, and it is unclear whether regional climate will
become more variable. The frequency and intensity of some
extreme weather of critical importance to ecological systems
(droughts, floods, frosts, cloudiness, the frequency of hot or cold
spells, and the intensity of associated fire and pest outbreaks)
could increase.
Local Climate Changes
Over the last century, the average temperature in New Brunswick.
New Jersey, has increased from 50.4°F (1889-1918 average) to
52.2°F (1966-1995 average), and precipitation in some locations
in the state has increased by 5-10%.
Over the next century, New Jersey's climate may change even
more. Based on projections given by the Intergovernmental Panel
on Climate Change and results from the United Kingdom Hadley
Centre's climate model (HadCM2), a model that accounts for
both greenhouse gases and aerosols, by 2100 temperatures in
New Jersey could increase about 4°F (with a range of 2-8°F) in
winter and spring, and slightly more in summer and fall, if
greenhouse-gas emissions are not controlled. Precipitation is
projected to increase by 10-20% (with a range of 0-40%), with
slightly less change in spring and slightly more in winter.
The amount of precipitation on extreme wet (or snowy) days
most likely would increase, but changes in the lengths of wet or
dry spells are not clear. The frequency of extreme hot days in
summer is expected to increase along with the general warming
trend. It is not clear how severe storms such as hurricanes would
change.
Climate Change Impacts
Global climate change poses risks to human health and to
terrestrial and aquatic ecosystems. Important economic resources
such as agriculture, forestry, fisheries, and water resources also
may be affected. Warmer temperatures, more severe droughts and
floods, and sea level rise could have a wide range of impacts. All
these stresses can add to existing stresses on resources caused by
other influences such as population growth, land-use changes,
and pollution.
Similar temperature changes have occurred in the past, but the
previous changes took place over centuries or millennia instead
of decades. The ability of some plants and animals to migrate and
adapt appears to be much slower than the predicted rate of
climate change.
Precipitation Trends From 1900 To Present
Trends/100 years
+20% A
+10% |
+5% •
Source: Karl et al. (1996)
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Human Health
Future Sea Level Rise At Atlantic City
Higher temperatures and increased frequency of heat waves may
increase the number of heat-related deaths and the incidence of
heat-related illnesses. New Jersey, with its irregular, intense heat
waves, seems very susceptible.
In Newark, one study projects that a 2-3°F warming could
increase heat-related deaths during a typical summer fivefold.
from about 25 today to near 125 (although increased air condi-
tioning use may not have been fully accounted for). Decreases in
winter mortality probably would be less than the summer mortal-
ity increases if the climate warms. The elderly, particularly those
living alone, are at greatest risk.
There is concern that climate change could increase ozone levels.
For example, high temperatures, strong sunlight, and stable air
masses tend to increase urban ozone levels. Furthermore, air
pollution also is made worse because natural hydrocarbons
emissions increase during hot weather. If a warmed climate
causes increased use of air conditioners, air pollutant emissions
from power plants also will increase.
A 4°F warming in New York City, with no other change in
weather or emissions, could increase concentrations of ozone, a
major component of smog, by 4%. Similar increases also could
occur in New Jersey. Current ozone concentrations exceed the
national health standards for ozone throughout the state. Virtually
all of New Jersey is classified as an "extreme and severe"
nonattainment area for ozone. Ground-level ozone has been
shown to aggravate existing respiratory illnesses such as asthma.
reduce lung function, and induce respiratory inflammation. In
addition, ambient ozone reduces agricultural crop yields and
impairs ecosystem health.
Warming and other climate changes could expand the habitat and
infectivity of disease-carrying insects, thus increasing the
potential for transmission of diseases such as malaria and dengue
("break bone") fever. Mosquitos flourish in some areas around
New Jersey. Some can carry malaria, while others can carry
Eastern equine encephalitis, which can be lethal or cause neuro-
logical damage. Lyme disease, which is carried by ticks, has
increased in the Northeast. If conditions become warmer and
wetter, mosquito and tick populations could increase, thereby
increasing the risk of transmission of these diseases.
In addition, warmer seas could contribute to the increased
intensity, duration, and extent of harmful algal blooms. These
blooms can damage habitat and shellfish nurseries, can be toxic
to humans, and can carry bacteria like those causing cholera.
Brown algal tides and toxic algal blooms already are prevalent in
the Atlantic. Warmer ocean waters could increase their occur-
rence and persistence.
Coastal Areas
Sea level rise could lead to flooding of low-lying property, loss of
coastal wetlands, erosion of beaches, saltwater contamination of
drinking water, and decreased longevity of low-lying roads.
01
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-ion
1 m
100
70
BO
^n
A.C\
30
on
10
n
5% Chance — i—
50% Chance — —
- 95% Chance -L-
-f
2050
2100 2150
Year
2200
Source: EPA (1995)
causeways, and bridges. In addition, sea level rise could increase
the vulnerability of coastal areas to storms and associated
flooding.
Along much of New Jersey's coast, sea level already is rising by
15 inches per century, and it is likely to rise another 27 inches by
2100. A large portion of New Jersey's 130-mile coastline is
vulnerable to extensive erosion and flooding from sea level rise
and storms. The New Jersey coastline is made up primarily of
long narrow barrier islands, low-lying salt marshes, and tidal
flats. Because of this topography, sea level rise could inflict
extensive damage on New Jersey's valuable, high-density coastal
real estate and recreational beaches. Rising seas also would
inundate many acres of New Jersey's remaining coastal salt
marshes and tidal flats that provide flood protection, water
quality benefits, and habitat for native species, as marsh plants
die or recede to higher elevations.
Protecting New Jersey's coast would require significant resources
and planning. For example, estimates of the cost of protecting
Long Beach Island with seawalls and more sand from a 1-3 foot
increase in sea level over the next century are $100-$500 million.
These costs could begin to accrue soon and continue to be
incurred throughout the next century.
Water Resources
Water resources are affected by changes in precipitation as well
as by temperature, humidity, wind, and sunshine. Changes in
streamflow tend to magnify changes in precipitation. Water
resources in drier climates tend to be more sensitive to climate
changes. Because evaporation from streams and lakes is likely to
increase with warmer climate, it could result in lower river flow
and lower lake levels, particularly in the summer. In addition.
more intense precipitation could increase flooding. If streamflow
and lake levels drop, groundwater also could be reduced.
Ensuring the supply of high quality municipal and industrial wa-
ter is the most critical water resource issue in New Jersey. About
half the state's potable water comes from streams and rivers, pri-
marily the Delaware, Raritan, and Passaic rivers, and numerous
small streams. The other half comes from groundwater. Except
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for that part of the Delaware River that flows from upper New
York State, winter snow accumulation has only a modest effect on
New Jersey streams. However, streamflow could decrease be-
cause of the increased evaporation that would accompany warmer
temperatures. The mean annual flow of the Delaware River at
Trenton could decrease about 15% if average temperatures warm
4.5°F and precipitation remains unchanged. Urbanization has
lowered water quality and increased flooding in many small New
Jersey rivers and streams, especially in the northern part of the
state. Reduced flows, especially in summer, would exacerbate the
decline in water quality. Many New Jersey aquifers also have
been contaminated because of industrial and urban development.
In the absence of increased precipitation, the amount of ground-
water available to refill the aquifers could decrease.
Agriculture
The mix of crop and livestock production in a state is influenced
by climatic conditions and water availability. As climate warms.
production patterns will shift northward. Increases in climate
variability could make adaptation by farmers more difficult.
Warmer climates and less soil moisture due to increased evapora-
tion may increase the need for irrigation. However, these same
conditions could decrease water supplies, which also may be
needed by natural ecosystems, urban populations, and other
economic sectors.
Understandably, most studies have not fully accounted for
changes in climate variability, water availability, and imperfect
responses by farmers to changing climate. Including these factors
could substantially change modeling results. Analyses based on
changes in average climate and which assume farmers effectively
adapt suggest that aggregate U.S. food production will not be
harmed, although there may be significant regional changes.
In New Jersey, agriculture is about a $0.7 billion annual industry.
two-thirds of which comes from crops. About 6% of New
Jersey's agricultural land is irrigated. The principal crops are hay.
corn, soybeans, and some vegetables. Projections of changes in
Changes In Agricultural Yield And Production
Yield Production
-50
Corn Hay
Soybeans Tomatoes
• DT = 7°F; Dprecip. = 1 %
Corn Hay
Soybeans Tomatoes
• DT= 10°F; Dprecip. = 10%
Source: Mendelsohn and Neumann (in press); McCarl (personal
communication)
New Jersey yield are mixed; they could range from up by 25% to
down by 38%. Climate change could lower total acres farmed and
production, as well as farm income.
Forests
Trees and forests are adapted to specific climate conditions, and
as climate warms, forests will change. These changes could
include changes in species, geographic extent, and health and
productivity. If conditions also become drier, the current range of
forests could be reduced and replaced by grasslands and pasture.
Even a warmer and wetter climate would lead to changes; trees
that are better adapted to warmer conditions, such as southern
pines, would prevail. Under these conditions, forests could be-
come more dense. These changes could occur during the lifetimes
of today's children, particularly if they are accelerated by other
stresses such as fire, pests, and diseases. Some of these stresses
would themselves be worsened by a warmer and drier climate.
With changes in climate, the extent and density of forested areas
in New Jersey could change little or could decline by as much as
10-20%. However, wildfire frequency almost certainly would
change with hotter and drier conditions. The types of trees
dominating New Jersey forests are likely to change. The mixed
forests, dominated by southern pines and oaks, would spread
northward throughout the state. These forests would replace the
predominantly hardwood forests currently found in the northern
half of the state.
Ecosystems
The most important ecosystems of New Jersey that would be
vulnerable to climate change are the coastal wetlands and the
forested Pine Barrens. The Pine Barrens cover approximately
1 million acres of the Outer Coastal Plain in southern and central
New Jersey. The Pine Barrens provide the habitat for rare and
unusual species, including the pine barrens treefrog, which is
protected by the Endangered Species Act. Because there are few
natural corridors that would allow migration of species, their
ability to adapt and migrate in response to climate change could
be limited.
Plant and animal species near the borders of their ranges are
likely to be most affected by climate change. Species better
adapted for cool conditions would need to migrate northward.
while southern species of plants and animals (including noxious
weeds such as kudzu and insect pests such as fire ants) could
spread into the state.
New Jersey's coastal wetlands are among the largest and most
diverse in the mid-Atlantic region. Sea level rise would alter
flooding and salinity, with substantial impacts on wildlife and
fisheries. Losses of tidal freshwater wetlands would be especially
harmful to foraging grounds for wading birds.
For further information about the potential impacts of climate
change, contact the Climate and Policy Assessment Division
(2174), U.S. EPA, 401 M Street SW, Washington, DC 20460.
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