United States
                           Environmental Protection
                           Agency
                           Office of Policy, Planning
                           and Evaluation
                           (2111)
                          EPA 230-F-97-008g
                          September 1997
      vxEPA        Climate  Change  And  Connecticut
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 enhanced by
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
      Solar
      radiation
      passes
      through
      the clear
      atmosphere
               Some solar radiation
                is reflected by the
                 earth and the
                 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.
                               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
     Source: U.S. Department of State (1992)

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      Global Temperature Changes (1861-1996)
03
0
I;-02
•0.4
•0.6
•0.8



f\
/x/Vv /\
/ \f
J
/\ A /
AA/W

f*

                               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

 Fora 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
temperature could increase an average of 1,6-6.3°F by 2100, with
significant 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 J 0.000 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, average temperatures in Storrs,
 Connecticut, have increased from 45.8°F (1892-1921  average)
 to 48.2°F (1966-1995 average), and precipitation in some
 locations has increased by 20%.

 Over the next century, Connecticut'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
 Connecticut could increase about 4°F (with a range of 2-8°F) in
 all seasons. Precipitation is projected to increase by 10-20%
 (with a range of 0-40%), with slightly less change in spring and
 summer 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 hurri-
canes would change, although an increase in the frequency and/or
intensity of winter storms is possible.


     Precipitation Trends  From 1900 To Present
     Trends/TOO years
         +20%
         + 10%
          +5%
                                                             Source: Karl et al. (1996)

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 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.
 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. Connecticut, with its irregular, intense heat
 waves, may be especially susceptible.

 In Hartford, one study projects that a 2°F warming could increase
 heat-related deaths during a typical summer by about 20%, from
 close to 40 heat-related deaths per summer to near 50 (although
 increased air conditioning use may not have been fully accounted
 for). Winter-related deaths are expected to change very little if
 the temperature warms by 2°F. 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 wanned
 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 could be
 expected in Connecticut. Currently, ground-level ozone concen-
 trations exceed national ozone health standards throughout the
 state. All of Connecticut is classified as a "serious" nonattainment
 area for ozone. Ground-level ozone has been shown to aggravate
 respiratory illnesses such as asthma, reduce existing lung func-
 tion, and induce respiratory inflammation. In addition, ambient
 ozone reduces 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
Connecticut. Some can carry malaria, while others can carry
Eastern equine encephalitis,  which can be lethal or cause neuro-
        Future Sea Level Rise At New London
110
100
90
80
70
60
50
40
30
20
10
0


5% Chance -
' 50% Chance—
95% Chance -
	 :,_ 	 .








. . x 	
T J




















2050 2100 2150 2200
Year
      Source: EPA (1995)
logical damage. Lyme disease, which is carried by ticks, has
increased in Connecticut. If conditions become warmer and
wetter and thus support larger populations of mosquitos and ticks,
these diseases may be transmitted more widely.

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 and toxic algal blooms already are prevalent in the
Atlantic. Warmer ocean waters could increase their occurrence
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,
causeways, and bridges. In addition, sea level rise could increase
the vulnerability of coastal  areas to storms and associated
flooding.

Along much of Connecticut's coast, sea level already is rising
8 inches per century, and it is likely to rise another 22 inches by
2100. Connecticut's coastline contains valuable residential
development and important wetlands ecosystems that would be
vulnerable to flooding from sea level rise. In particular,
Connecticut has extensive tidal flats and diverse nontidal fresh-
water marshes. Because Long Island Sound may reduce wave
action, some of these wetlands may be protected with a tempo-
rary buffer from erosion. Connecticut's freshwater marshes,
however, are likely to be harmed by saltwater intrusion.

Cumulative costs through 2100 to protect Connecticut's coastline
from a 20-inch sea level rise could be $0.5-$3 billion.

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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.

The Connecticut River is susceptible to changes in winter snow
accumulation, which would be reduced in a warmer climate.
Peak spring streamflows in the Connecticut River could occur
several weeks earlier if the climate were to warm about 4°F. The
Housatanic and Thames rivers could see similar but smaller
changes. Without increased precipitation, groundwater would
decrease in a wanner climate, which would reduce Connecticut's
aquifers.
   Changes In Agricultural Yield And Production

                Yield                     Production
          Silage      Hay
            S3 AT = 7"F; Aprecip. = -1%
   Silage      ~ Hay
I AT = 10"F; Aprecip. = 12%
Source: Mendelsohn and Neumann (in press); McCarl (personal
communication)
 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
 banned, although there may be significant regional changes.

 In Connecticut, agriculture is a S500 million annual industry.
 About one-twentieth of 1$ of total U.S. farm acres is in the state.
 The principal crops are silage and hay, and very little of the
 agricultural land is irrigated. Projections of changes in
 Connecticut yields are mixed; they could range from little change
 to decreases of almost 40%. Total acres farmed would remain
 about the same, but farm income could decrease by about 50%.
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
and density of forests could be reduced and replaced by grass-
lands and pasture. Even a warmer and wetter climate would lead
to changes; trees that are better adapted to these conditions, such
as oaks and redwoods, would thrive. Under these conditions,
forests could become 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 of forested areas in
Connecticut could change little. However, a warmer climate
could change the character of Connecticut's forests. Maple-
dominated hardwood forests could give way to  forests dominated
by oaks and conifers, species more tolerant of higher tempera-
tures. This change would diminish the brilliant autumn foliage as
the contribution of maples declines. Across the state, as much as
30-60% of the hardwood forests could be replaced by warmer
climate forests with a mix of pines and hardwoods.
                                                               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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