United States
Environmental Protection
Agency
Office of Policy, Planning
and Evaluation
(2111)
EPA 230-F-97-008ff
September 1997
<>EPA Climate Change And New York
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
k 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. Of these, 1995 was the warmest
year on record, suggesting the atmosphere has rebounded from
the temporary cooling caused by the eruption of Mt. Pinatubo in
the Philippines.
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
1
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Global Temperature Changes (1861-1996)
Year
Source: IPCC (1995), updated
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.
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. As a result of continuous model improvements over the
last few decades, scientists are reasonably confident about the
link between global greenhouse gas concentrations and tempera-
ture and 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, temperatures in Albany, New York, have
warmed by more than 1°F, and precipitation throughout the state
has increased by up to 20%.
Over the next century, New York'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 has accounted
for both greenhouse gases and aerosols, by 2100 temperatures in
New York could increase about 4°F in winter and spring, and
slightly more in summer and fall (with a range of 2-8°F).
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 is
likely to 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.
Precipitation Trends From 1900 To Present
Trends/100 years
+20%
+10%
+5%
Source: Karl et al. (1996)
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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.
Human Health
Higher temperatures and increased frequency of heat waves may
increase the number of heat-related deaths and the incidence of
heat-related illnesses. New York, with its irregular, intense heat
waves, could be especially susceptible.
In New York City, one study projects that a 1°F warming could
more than double heat-related deaths during a typical summer.
from about 300 today to over 700 (although increased air
conditioning use may not have been fully accounted for).
Decreases in winter mortality probably would be less than the
summer mortality increases if the climate warms. The elderly.
particularly those living alone, are at greatest risk.
There is concern that climate change could increase concentra-
tions of ground-level ozone. For example, high temperatures.
strong sunlight, and stable air masses tend to increase urban
ozone levels. Air pollution also is made worse by increases in
natural hydrocarbons emissions 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, would increase concentrations of ground-
level ozone, a major component of smog, by 4%. Current ozone
concentrations exceed the national health standards in many
urban areas, especially New York City and Long Island. 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 may expand the habitat and
infectivity of disease-carrying insects, increasing the potential for
transmission of diseases such as malaria and dengue ("break
bone") fever. Mosquitoes flourish in some areas around New
York City. Some can carry malaria, while others can carry Eastern
equine encephalitis, which can be lethal or cause neurological
damage. Lyme disease, which is carried by ticks, has increased in
New York. 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 damage habitat and shellfish nurseries, can be toxic to
humans, and can carry bacteria, like those causing cholera.
Brown algal tides already are prevalent in the Atlantic. Warmer
ocean waters could increase their occurrence and persistence.
Changes In Forest Cover
Current +10°F, +13% Precipitation
Conifer Forest
Broadleaf Forest
Savanna/Woodland
Grassland
Source: VEMAP Participants (1995); Neilson (1995)
Forests
Trees and forests are adapted to specific climate conditions, and
as climate warms, forests will change. This would include
changes in species, geographic extent, and health and productiv-
ity. If conditions also become drier, the current range of forests
might 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. Forests could, under these conditions, become
more dense. These changes might 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 of forested areas in New York
could change little or could decline by as much as 10-25%.
However, the types of trees dominating New York forests are
likely to change. The predominant maple, beech, and birch
forests found in northern and western New York would retreat
northward. The brilliant autumn foliage of the maples eventually
could give way to forests dominated by oaks, ash, and pines.
Across the state, as much as 50-70% of the maple forests could
be lost. As a result, the character of heavily visited areas such as
the Adirondacks may change.
Coastal Areas
Along much of New York's coast, sea level already is rising
10 inches per century, and it is likely to rise another 22 inches by
2100. Sea level rise can lead to flooding of low-lying areas, loss
of coastal wetlands, erosion of beaches, saltwater contamination
of drinking water, and decreased longevity of low-lying roads.
causeways, and bridges. In addition, sea level rise could increase
the vulnerability of coastal areas to storms and associated
flooding.
New York has one of the most urbanized coastlines in the United
States. Over 20 million people use New York's beaches and
coastal regions for recreation each year. New York has been
successful at preventing major permanent losses of its beaches
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and urban coastline, but sites such as Long Island continue to
suffer from chronic beach erosion. Long Island's south shore.
which is made up of barrier islands, barrier spits, ponds, and sand
beaches, could suffer extensive damage from sea level rise and
coastal storms.
Protecting New York's coast would require significant resources
and planning. For example, Manhattan's 29-mile coast probably
could be protected by raising existing bulkheads and sea walls at
a cumulative cost of $30-$140 million for a 1-3 foot rise in sea
level. The costs of raising existing bulkheads already have begun
to accrue, and they could continue 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 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.
Scientists are unable to predict whether streamflow in New York
would rise or fall on average. However, there could be higher
streamflow in the winter and lower streamflow in spring and
summer. Changes in the seasonality of streamflow (more in
winter, less in summer) would make it difficult for the water
supply systems in cities like New York to meet current demands
reliably. In addition, higher temperatures and lower flow could
reduce water quality in New York's rivers and streams.
Increased evaporation probably would reduce the average levels
of Lakes Erie and Ontario by up to a foot. These changes would
exacerbate water quality problems in those lakes, as well as in the
numerous smaller lakes in the St. Lawrence River basin. Lower
water levels in Lakes Erie and Ontario would reduce flood
damages, but shore erosion would increase from wind and rain.
The ice-free season for the St. Lawrence Seaway would be
longer, with positive benefits to navigation.
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.
Changes In Agricultural Yield And Production
Yield Production
Corn Silage Hay Corn Silage Hay
• DT = 7°F;Dprecip. = -2% • DT= 10°F;Dprecip.= 13%
Source: Mendelsohn and Neumann (in press); McCarl (personal
communication)
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 York, agriculture is about a $3 billion a year industry.
two-thirds of which comes from dairy livestock. The major crops
in the state are hay, corn, and silage. Changes in New York yields
could range from 0 to -40%. Climate change could lower
production and farm income, but total acres farmed most likely
would remain constant. Although very little land is currently
irrigated, irrigated acreage probably would increase with climate
change.
Ecosystems
The ecosystems of New York are quite diverse, ranging from
coastal marshes to mountain forests. These ecosystems would be
affected by everything from sea level rise to changes in fires and
pest outbreaks. Sea level rise could alter food availability for
wading birds and other animals in the coastal areas because of
loss of wetlands. In higher elevation wetlands, climate warming
could reduce streamflow and lake levels, which would result in
losses of vegetation such as cranberries. Brook trout habitat and
fisheries, which require cold temperatures, could be lost entirely
throughout New York, and most of the habitat for brown trout
could be lost.
Adirondack State Park is the largest single forested area east of
the Mississippi, consisting of 6 million acres, 2.6 million of
which are a forest preserve. The park represents one of the most
significant hardwood ecosystems in the world. A warmer climate
could change the types and extent of forests. The migration of
species to new locations out of the park could be impeded by
economic development around the park.
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
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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