United States
Environmental Protection
United States
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What Climate Change
Means ^Connecticut
August 2016
EPA 430-F-16-009
Connecticut's climate is changing. The state has warmed two
to three degrees (F) in the last century. Throughout the north-
eastern United States, spring is arriving earlier and bringing more
precipitation, heavy rainstorms are more frequent, and summers
are hotter and drier. Sea level is rising, and severe storms in-
creasingly cause floods that damage property and infrastructure.
In the coming decades, changing the climate is likely to increase
flooding, harm ecosystems, disrupt farming, and increase some
risks to human health.
Our climate is changing because the earth is warming. Since
the late 1700s, people have increased the amount of carbon
dioxide in the air by 40 percent. Other heat-trapping green-
house gases are also increasing. These gases have warmed
the surface and lower atmosphere of our planet about one
degree during the last 50 years. Evaporation increases as the
atmosphere warms, which increases humidity, average rainfall,
and the frequency of heavy rainstorms in many places—but
contributes to drought in others.
Increasing Temperature and Changing
Precipitation Patterns
Rising temperatures and shifting rainfall patterns are likely to
increase the intensity of both floods and droughts. Average
annual precipitation in the Northeast increased 10 percent
from 1895 to 2011, and precipitation from extremely heavy
storms has increased 70 percent since 1958. During the
next century, average annual precipitation and the frequency
of heavy downpours are likely to keep rising. Average
precipitation is likely to increase during winter and spring,
but not change significantly during summer and fall. Rising
temperatures will melt snow earlier in spring and increase
evaporation, and thereby dry the soil during summer and fall
So flooding is likely to be worse during winter and spring, and
droughts worse during summer and fall.
Temperature change (°F):
-1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5
Rising temperatures in the last century. Connecticut has warmed
twice as much as the rest of the contiguous 48 states. Source: EPA,
Climate Change Indicators in the United States.
in 2011, Hurricane Irene filled the Connecticut River with
muddy sediment as a result of erosion upstream. Heavy storms
are becoming more common as a result of climate change.
Credit: NASA.
Greenhouse gases are also changing the world's oceans and ice
cover. Carbon dioxide reacts with water to form carbonic acid, so
the oceans are becoming more acidic. The surface of the ocean
has warmed about one degree during the last 80 years. Warming
is causing snow to melt earlier in spring, and mountain glaciers
are retreating. Even the great ice sheets on Greenland and
Antarctica are shrinking. Thus the sea is rising at an increasing

Sea Level Rise, Wetland Loss, and Coastal
Rising sea level erodes wetlands and beaches and increases
damage from coastal storms. Tidal wetlands are inherently
vulnerable because of their low elevations, and shoreline devel-
opment prevents them from migrating inland onto higher ground.
Human activities such as filling wetlands have destroyed about
one third of New England's coastal wetlands since the early
1800s. Wetlands provide habitat for many bird species, such as
osprey and heron, as well as several fish species. Losing coastal
wetlands would harm coastal ecosystems and remove an im-
portant line of defense against coastal flooding.
Coastal cities and towns will become more vulnerable to storms
in the coming century as sea level rises, shorelines erode,
and storm surges become higher. Storms can destroy coastal
homes, wash out highways and rail lines, and damage essential
communication, energy, and wastewater management infra-
Coastal marshes in Old Saybrook and neaiby properties are at risk from
sea level rise. © James G. Titus; used by permission.
Ecosystems and Agriculture
Changing the climate threatens ecosystems by disrupting
relationships between species. Wildflowers and woody
perennials are blooming—and migratory birds are arriving—
sooner in spring. Not all species adjust in the same way,
however, so the food that one species needs may no longer be
available when that species arrives on its migration. Warmer
temperatures allow deer populations to increase, leading to a
loss of forest underbrush, which makes some animals more
vulnerable to predators. Rising temperatures also enable
invasive species to move into areas that were previously too
Climate change may also pose challenges for agriculture:
Warmer temperatures cause cows to eat less and produce less
milk. That could reduce the output of Connecticut's $70-million
dairy industry, which provides 13 percent of the state's farm
revenue. Some farms may be harmed if more hot days and
droughts reduce crop yields, or if more flooding and wetter
springs delay their planting dates. Other farms may benefit from
a longer growing season and the fertilizing effect of carbon
Human Health
Changes in temperature and precipitation could increase the
incidence of acute and chronic respiratory conditions such as
asthma. Higher temperatures can increase the formation of
ground-level ozone (smog), a pollutant that can contribute to
respiratory problems. Rising temperatures may also increase
the length and severity of the pollen season for plants such as
ragweed—which has already been observed in other regions.
Certain people are especially vulnerable, including children, the
elderly, the sick, and the poor.
The risk of some diseases carried by insects may also increase.
The ticks that transmit Lyme disease are active when tempera-
tures are above 45°F, so warmer winters could lengthen the
season during which ticks can become infected or people can
be exposed to the ticks. Higher temperatures would also make
more of New England warm enough for the Asian tiger mosquito,
a common carrier of West Nile virus. The number of cases may
or may not increase, depending on what people do to control
insect populations and avoid insect bites.
The sources of information about climate and the impacts of climate change in this publication are: the national climate assessments by the U.S. Global Change
Research Program, synthesis and assessment products by the U.S. Climate Change Science Program, assessment reports by the Intergovernmental Panel on Climate
Change, and EPA!s Climate Change indicators in the United States. Mention of a particular season, location, species, or any other aspect of an impact does not imply
anything about the likelihood or importance of aspects that are not mentioned. For more information about climate change science, impacts, responses, and what you
can do, visit EPA's Climate Change website at www.epa.aov/clirnatechanae.