4Rh	United States
Environmental Protection
United States	AliOUSt 2016
Environmental Protection
Agency	EPA 430-F-16-031
What Climate Change
Means for[
New Hampshire
New Hampshire's climate is changing. Most of the state has
warmed two to three degrees (F) in the last century. Throughout
the northeastern 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 cause floods that damage property and infrastructure. In
the coming decades, the changing climate is likely to increase
flooding, harm ecosystems and winter recreation, disrupt
farming, and increase some risks to human health.
Our climate is changing because the earth is warming. People
have increased the amount of carbon dioxide in the air by
40 percent since the late 1700s. Other heat-trapping greenhouse
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.
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
rate.
Temperature change (°F):
-1 -0,5 0 0.5 1 1.5 2 2.5 3 B.5
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 precipi-
tation is likely to increase during winter and spring, but not
change significantly during summer and fall. Rising tempera-
tures 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.

Rising temperatures in the last century. New Hampshire has warned
twice as much as the rest of the contiguous 48 states. Source: EPA.
Climate Change Indicators in the United States.
Torrential downpours flooded Alstead and neighboring communities
in 2005, causing millions of dollars of damage. Credit: EPA.
Winter Recreation
Warmer winters may bring more rain and less snow to New
Hampshire. A decline in snowfall would shorten the season
during which the ground is covered with snow, which could
harm recreational industries like skiing, snowboarding, and
snowmobiling, and the local economies that depend on them.
Agriculture
Climate change may pose challenges for agriculture. 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 dioxide.

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Sea Level Rise, Wetland Loss, and Coastal Flooding
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
development 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
important 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 commu-
nication, energy, and wastewater management infrastructure.
The Great Bay area has marshes and infrastructure that are at risk from
sea level rise. © Ben Miller; used by peimission.
Ecosystems
Changing the climate threatens ecosystems by disrupting relation-
ships 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. Rising temperatures allow deer popula-
tions to increase, reducing forest underbrush, which makes some
animals more vulnerable to predators.
Climate change can allow invasive species to expand their
ranges. For example, the hemlock woolly adelgid has infested
hemlock trees in southern New Hampshire. Infestation eventually
kills almost all hemlock trees, which are replaced by black oaks,
A
black birch, and other hardwoods. Warmer temperatures are
likely to enable the woolly adelgid to expand northward. The
loss of hemlock trees would remove the primary habitat for the
blue-headed vireo and Blackburnian warbler. It could also change
stream temperatures and cause streams to run dry more often,
harming brook trout and brown trout.
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.
Increase in Lyme disease between 1996 and 2013, Each dark dot
shows one case reported in 1996; light dots show 2013. The increased
range shown here has been attributed to factors other than ciimate
change. Nevertheless, additional warming will lengthen the season
during which people are exposed to Lyme disease and may allow the
disease to spread to colder areas. Source: CDC.
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 ciimate change science, impacts, responses, and what you can do, visit EPA!s
Climate Change website atwww.epa.gov/climatechanae.

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